Merge branch 'circular-import'

30 files changed, 375 insertions, 331 deletions

diff --git a/qutebrowser/browser/downloadview.py b/qutebrowser/browser/downloadview.py
index 91a583d08..b0944046b 100644
--- a/qutebrowser/browser/downloadview.py
+++ b/qutebrowser/browser/downloadview.py
@@ -26,7 +26,7 @@ from PyQt5.QtCore import pyqtSlot, QSize, Qt, QTimer
 from PyQt5.QtWidgets import QListView, QSizePolicy, QMenu, QStyleFactory
 
 from qutebrowser.browser import downloads
-from qutebrowser.config import config
+from qutebrowser.config import stylesheet
 from qutebrowser.utils import qtutils, utils
 from qutebrowser.qt import sip
 
@@ -85,7 +85,7 @@ class DownloadView(QListView):
         super().__init__(parent)
         if not utils.is_mac:
             self.setStyle(QStyleFactory.create('Fusion'))
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
         self.setResizeMode(QListView.Adjust)
         self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
         self.setSizePolicy(QSizePolicy.MinimumExpanding, QSizePolicy.Fixed)
diff --git a/qutebrowser/browser/webkit/webview.py b/qutebrowser/browser/webkit/webview.py
index 1cd9d0a2a..88daf06aa 100644
--- a/qutebrowser/browser/webkit/webview.py
+++ b/qutebrowser/browser/webkit/webview.py
@@ -24,7 +24,7 @@ from PyQt5.QtWidgets import QStyleFactory
 from PyQt5.QtWebKit import QWebSettings
 from PyQt5.QtWebKitWidgets import QWebView, QWebPage
 
-from qutebrowser.config import config
+from qutebrowser.config import config, stylesheet
 from qutebrowser.keyinput import modeman
 from qutebrowser.utils import log, usertypes, utils, objreg, debug
 from qutebrowser.browser.webkit import webpage
@@ -84,7 +84,7 @@ class WebView(QWebView):
 
         self.setPage(page)
 
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
 
     def __repr__(self):
         urlstr = self.url().toDisplayString(QUrl.EncodeUnicode)  # type: ignore
diff --git a/qutebrowser/completion/completionwidget.py b/qutebrowser/completion/completionwidget.py
index 4d90a4305..5b1b080e4 100644
--- a/qutebrowser/completion/completionwidget.py
+++ b/qutebrowser/completion/completionwidget.py
@@ -28,7 +28,7 @@ import typing
 from PyQt5.QtWidgets import QTreeView, QSizePolicy, QStyleFactory, QWidget
 from PyQt5.QtCore import pyqtSlot, pyqtSignal, Qt, QItemSelectionModel, QSize
 
-from qutebrowser.config import config
+from qutebrowser.config import config, stylesheet
 from qutebrowser.completion import completiondelegate
 from qutebrowser.utils import utils, usertypes, debug, log
 from qutebrowser.api import cmdutils
@@ -125,7 +125,7 @@ class CompletionView(QTreeView):
         self._delegate = completiondelegate.CompletionItemDelegate(self)
         self.setItemDelegate(self._delegate)
         self.setStyle(QStyleFactory.create('Fusion'))
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
         self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
         self.setHeaderHidden(True)
         self.setAlternatingRowColors(True)
diff --git a/qutebrowser/config/config.py b/qutebrowser/config/config.py
index 7e10a91f3..41ef6eb3d 100644
--- a/qutebrowser/config/config.py
+++ b/qutebrowser/config/config.py
@@ -23,13 +23,13 @@ import copy
 import contextlib
 import functools
 import typing
-from typing import Any, Optional, FrozenSet
+from typing import Any, Optional
 
-from PyQt5.QtCore import pyqtSignal, pyqtSlot, QObject, QUrl
+from PyQt5.QtCore import pyqtSignal, QObject, QUrl
 
 from qutebrowser.config import configdata, configexc, configutils
-from qutebrowser.utils import utils, log, jinja, urlmatch
-from qutebrowser.misc import objects, debugcachestats
+from qutebrowser.utils import utils, log, urlmatch
+from qutebrowser.misc import objects
 from qutebrowser.keyinput import keyutils
 
 if typing.TYPE_CHECKING:
@@ -278,7 +278,6 @@ class Config(QObject):
                  yaml_config: 'configfiles.YamlConfig',
                  parent: QObject = None) -> None:
         super().__init__(parent)
-        self.changed.connect(_render_stylesheet.cache_clear)
         self._mutables = {}  # type: MutableMapping[str, Tuple[Any, Any]]
         self._yaml = yaml_config
         self._init_values()
@@ -397,7 +396,7 @@ class Config(QObject):
         """Get the given setting as object (for YAML/config.py).
 
         This gets the overridden value for a given pattern, or
-        configutils.UNSET if no such override exists.
+        usertypes.UNSET if no such override exists.
         """
         self.ensure_has_opt(name)
         value = self._values[name].get_for_pattern(pattern, fallback=False)
@@ -434,7 +433,7 @@ class Config(QObject):
         """Get the given setting as string.
 
         If a pattern is given, get the setting for the given pattern or
-        configutils.UNSET.
+        usertypes.UNSET.
         """
         opt = self.get_opt(name)
         values = self._values[name]
@@ -617,86 +616,3 @@ class ConfigContainer:
             return '{}.{}'.format(self._prefix, attr)
         else:
             return attr
-
-
-def set_register_stylesheet(obj: QObject, *,
-                            stylesheet: str = None,
-                            update: bool = True) -> None:
-    """Set the stylesheet for an object.
-
-    Also, register an update when the config is changed.
-
-    Args:
-        obj: The object to set the stylesheet for and register.
-             Must have a STYLESHEET attribute if stylesheet is not given.
-        stylesheet: The stylesheet to use.
-        update: Whether to update the stylesheet on config changes.
-    """
-    observer = StyleSheetObserver(obj, stylesheet, update)
-    observer.register()
-
-
-@debugcachestats.register()
-@functools.lru_cache()
-def _render_stylesheet(stylesheet: str) -> str:
-    """Render the given stylesheet jinja template."""
-    with jinja.environment.no_autoescape():
-        template = jinja.environment.from_string(stylesheet)
-    return template.render(conf=val)
-
-
-class StyleSheetObserver(QObject):
-
-    """Set the stylesheet on the given object and update it on changes.
-
-    Attributes:
-        _obj: The object to observe.
-        _stylesheet: The stylesheet template to use.
-        _options: The config options that the stylesheet uses. When it's not
-                  necessary to listen for config changes, this attribute may be
-                  None.
-    """
-
-    def __init__(self, obj: QObject,
-                 stylesheet: Optional[str], update: bool) -> None:
-        super().__init__()
-        self._obj = obj
-        self._update = update
-
-        # We only need to hang around if we are asked to update.
-        if update:
-            self.setParent(self._obj)
-        if stylesheet is None:
-            self._stylesheet = obj.STYLESHEET  # type: str
-        else:
-            self._stylesheet = stylesheet
-
-        if update:
-            self._options = jinja.template_config_variables(
-                self._stylesheet)  # type: Optional[FrozenSet[str]]
-        else:
-            self._options = None
-
-    def _get_stylesheet(self) -> str:
-        """Format a stylesheet based on a template.
-
-        Return:
-            The formatted template as string.
-        """
-        return _render_stylesheet(self._stylesheet)
-
-    @pyqtSlot(str)
-    def _maybe_update_stylesheet(self, option: str) -> None:
-        """Update the stylesheet for obj if the option changed affects it."""
-        assert self._options is not None
-        if option in self._options:
-            self._obj.setStyleSheet(self._get_stylesheet())
-
-    def register(self) -> None:
-        """Do a first update and listen for more."""
-        qss = self._get_stylesheet()
-        log.config.vdebug(  # type: ignore
-            "stylesheet for {}: {}".format(self._obj.__class__.__name__, qss))
-        self._obj.setStyleSheet(qss)
-        if self._update:
-            instance.changed.connect(self._maybe_update_stylesheet)
diff --git a/qutebrowser/config/configexc.py b/qutebrowser/config/configexc.py
index d83ca403b..53b6689f8 100644
--- a/qutebrowser/config/configexc.py
+++ b/qutebrowser/config/configexc.py
@@ -22,7 +22,7 @@
 import typing
 import attr
 
-from qutebrowser.utils import jinja, usertypes, log
+from qutebrowser.utils import usertypes, log
 
 
 class Error(Exception):
@@ -155,6 +155,7 @@ class ConfigFileErrors(Error):
 
     def to_html(self) -> str:
         """Get the error texts as a HTML snippet."""
+        from qutebrowser.utils import jinja  # circular import
         template = jinja.environment.from_string("""
         Errors occurred while reading {{ basename }}:
 
diff --git a/qutebrowser/config/configinit.py b/qutebrowser/config/configinit.py
index 21f7fa054..e2c359e72 100644
--- a/qutebrowser/config/configinit.py
+++ b/qutebrowser/config/configinit.py
@@ -28,7 +28,7 @@ from PyQt5.QtWidgets import QMessageBox
 
 from qutebrowser.api import config as configapi
 from qutebrowser.config import (config, configdata, configfiles, configtypes,
-                                configexc, configcommands)
+                                configexc, configcommands, stylesheet)
 from qutebrowser.utils import (objreg, usertypes, log, standarddir, message,
                                qtutils)
 from qutebrowser.config import configcache
@@ -88,6 +88,8 @@ def early_init(args: argparse.Namespace) -> None:
     configtypes.Font.monospace_fonts = config.val.fonts.monospace
     config.instance.changed.connect(_update_monospace_fonts)
 
+    stylesheet.init()
+
     _init_envvars()
 
 
diff --git a/qutebrowser/config/configtypes.py b/qutebrowser/config/configtypes.py
index be1f7edcf..475879de0 100644
--- a/qutebrowser/config/configtypes.py
+++ b/qutebrowser/config/configtypes.py
@@ -61,7 +61,7 @@ from PyQt5.QtWidgets import QTabWidget, QTabBar
 from PyQt5.QtNetwork import QNetworkProxy
 
 from qutebrowser.misc import objects, debugcachestats
-from qutebrowser.config import configexc, configutils
+from qutebrowser.config import configexc
 from qutebrowser.utils import (standarddir, utils, qtutils, urlutils, urlmatch,
                                usertypes)
 from qutebrowser.keyinput import keyutils
@@ -80,8 +80,8 @@ BOOLEAN_STATES = {'1': True, 'yes': True, 'true': True, 'on': True,
 
 
 _Completions = typing.Optional[typing.Iterable[typing.Tuple[str, str]]]
-_StrUnset = typing.Union[str, configutils.Unset]
-_StrUnsetNone = typing.Union[None, str, configutils.Unset]
+_StrUnset = typing.Union[str, usertypes.Unset]
+_StrUnsetNone = typing.Union[None, str, usertypes.Unset]
 
 
 class ValidValues:
@@ -168,7 +168,7 @@ class BaseType:
             value: The value to check.
             pytype: A Python type to check the value against.
         """
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return
 
         if (value is None or (pytype == list and value == []) or
@@ -342,7 +342,7 @@ class MappingType(BaseType):
 
     def to_py(self, value: typing.Any) -> typing.Any:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -408,7 +408,7 @@ class String(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -450,7 +450,7 @@ class UniqueCharString(String):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         py_value = super().to_py(value)
-        if isinstance(py_value, configutils.Unset):
+        if isinstance(py_value, usertypes.Unset):
             return py_value
         elif not py_value:
             return None
@@ -510,10 +510,10 @@ class List(BaseType):
 
     def to_py(
             self,
-            value: typing.Union[typing.List, configutils.Unset]
-    ) -> typing.Union[typing.List, configutils.Unset]:
+            value: typing.Union[typing.List, usertypes.Unset]
+    ) -> typing.Union[typing.List, usertypes.Unset]:
         self._basic_py_validation(value, list)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return []
@@ -601,7 +601,7 @@ class ListOrValue(BaseType):
         return value
 
     def to_py(self, value: typing.Any) -> typing.Any:
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
 
         try:
@@ -652,10 +652,10 @@ class FlagList(List):
 
     def to_py(
             self,
-            value: typing.Union[configutils.Unset, typing.List],
-    ) -> typing.Union[configutils.Unset, typing.List]:
+            value: typing.Union[usertypes.Unset, typing.List],
+    ) -> typing.Union[usertypes.Unset, typing.List]:
         vals = super().to_py(value)
-        if not isinstance(vals, configutils.Unset):
+        if not isinstance(vals, usertypes.Unset):
             self._check_duplicates(vals)
         return vals
 
@@ -866,10 +866,10 @@ class Perc(_Numeric):
 
     def to_py(
             self,
-            value: typing.Union[None, float, int, str, configutils.Unset]
-    ) -> typing.Union[None, float, int, configutils.Unset]:
+            value: typing.Union[None, float, int, str, usertypes.Unset]
+    ) -> typing.Union[None, float, int, usertypes.Unset]:
         self._basic_py_validation(value, (float, int, str))
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1062,10 +1062,10 @@ class QtColor(BaseType):
         except ValueError:
             raise configexc.ValidationError(val, "must be a valid color value")
 
-    def to_py(self, value: _StrUnset) -> typing.Union[configutils.Unset,
+    def to_py(self, value: _StrUnset) -> typing.Union[usertypes.Unset,
                                                       None, QColor]:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1123,7 +1123,7 @@ class QssColor(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1170,7 +1170,7 @@ class Font(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1191,7 +1191,7 @@ class FontFamily(Font):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1215,10 +1215,10 @@ class QtFont(Font):
 
     __doc__ = Font.__doc__  # for src2asciidoc.py
 
-    def to_py(self, value: _StrUnset) -> typing.Union[configutils.Unset,
+    def to_py(self, value: _StrUnset) -> typing.Union[usertypes.Unset,
                                                       None, QFont]:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1333,11 +1333,11 @@ class Regex(BaseType):
 
     def to_py(
             self,
-            value: typing.Union[str, typing.Pattern[str], configutils.Unset]
-    ) -> typing.Union[configutils.Unset, None, typing.Pattern[str]]:
+            value: typing.Union[str, typing.Pattern[str], usertypes.Unset]
+    ) -> typing.Union[usertypes.Unset, None, typing.Pattern[str]]:
         """Get a compiled regex from either a string or a regex object."""
         self._basic_py_validation(value, (str, self._regex_type))
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1425,10 +1425,10 @@ class Dict(BaseType):
 
     def to_py(
             self,
-            value: typing.Union[typing.Dict, configutils.Unset, None]
-    ) -> typing.Union[typing.Dict, configutils.Unset]:
+            value: typing.Union[typing.Dict, usertypes.Unset, None]
+    ) -> typing.Union[typing.Dict, usertypes.Unset]:
         self._basic_py_validation(value, dict)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return self._fill_fixed_keys({})
@@ -1477,7 +1477,7 @@ class File(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1509,7 +1509,7 @@ class Directory(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1546,7 +1546,7 @@ class FormatString(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1590,10 +1590,10 @@ class ShellCommand(List):
 
     def to_py(
             self,
-            value: typing.Union[typing.List, configutils.Unset],
-    ) -> typing.Union[typing.List, configutils.Unset]:
+            value: typing.Union[typing.List, usertypes.Unset],
+    ) -> typing.Union[typing.List, usertypes.Unset]:
         py_value = super().to_py(value)
-        if isinstance(py_value, configutils.Unset):
+        if isinstance(py_value, usertypes.Unset):
             return py_value
         elif not py_value:
             return []
@@ -1624,9 +1624,9 @@ class Proxy(BaseType):
     def to_py(
             self,
             value: _StrUnset
-    ) -> typing.Union[configutils.Unset, None, QNetworkProxy, _SystemProxy]:
+    ) -> typing.Union[usertypes.Unset, None, QNetworkProxy, _SystemProxy]:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1666,7 +1666,7 @@ class SearchEngineUrl(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1696,7 +1696,7 @@ class FuzzyUrl(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1732,10 +1732,10 @@ class Padding(Dict):
 
     def to_py(  # type: ignore
             self,
-            value: typing.Union[configutils.Unset, typing.Dict, None],
-    ) -> typing.Union[configutils.Unset, PaddingValues]:
+            value: typing.Union[usertypes.Unset, typing.Dict, None],
+    ) -> typing.Union[usertypes.Unset, PaddingValues]:
         d = super().to_py(value)
-        if isinstance(d, configutils.Unset):
+        if isinstance(d, usertypes.Unset):
             return d
 
         return PaddingValues(**d)
@@ -1747,7 +1747,7 @@ class Encoding(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1807,9 +1807,9 @@ class Url(BaseType):
     def to_py(
             self,
             value: _StrUnset
-    ) -> typing.Union[configutils.Unset, None, QUrl]:
+    ) -> typing.Union[usertypes.Unset, None, QUrl]:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1827,7 +1827,7 @@ class SessionName(BaseType):
 
     def to_py(self, value: _StrUnset) -> _StrUnsetNone:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1877,10 +1877,10 @@ class ConfirmQuit(FlagList):
 
     def to_py(
             self,
-            value: typing.Union[configutils.Unset, typing.List],
-    ) -> typing.Union[typing.List, configutils.Unset]:
+            value: typing.Union[usertypes.Unset, typing.List],
+    ) -> typing.Union[typing.List, usertypes.Unset]:
         values = super().to_py(value)
-        if isinstance(values, configutils.Unset):
+        if isinstance(values, usertypes.Unset):
             return values
         elif not values:
             return []
@@ -1921,9 +1921,9 @@ class Key(BaseType):
     def to_py(
             self,
             value: _StrUnset
-    ) -> typing.Union[configutils.Unset, None, keyutils.KeySequence]:
+    ) -> typing.Union[usertypes.Unset, None, keyutils.KeySequence]:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
@@ -1945,9 +1945,9 @@ class UrlPattern(BaseType):
     def to_py(
             self,
             value: _StrUnset
-    ) -> typing.Union[configutils.Unset, None, urlmatch.UrlPattern]:
+    ) -> typing.Union[usertypes.Unset, None, urlmatch.UrlPattern]:
         self._basic_py_validation(value, str)
-        if isinstance(value, configutils.Unset):
+        if isinstance(value, usertypes.Unset):
             return value
         elif not value:
             return None
diff --git a/qutebrowser/config/configutils.py b/qutebrowser/config/configutils.py
index 506c8eeda..1a7f612cb 100644
--- a/qutebrowser/config/configutils.py
+++ b/qutebrowser/config/configutils.py
@@ -28,24 +28,20 @@ import operator
 
 from PyQt5.QtCore import QUrl
 
-from qutebrowser.utils import utils, urlmatch, urlutils
+from qutebrowser.utils import utils, urlmatch, usertypes
 from qutebrowser.config import configexc
 
 if typing.TYPE_CHECKING:
     from qutebrowser.config import configdata
 
 
-class Unset:
+def _widened_hostnames(hostname: str) -> typing.Iterable[str]:
+    """A generator for widening string hostnames.
 
-    """Sentinel object."""
-
-    __slots__ = ()
-
-    def __repr__(self) -> str:
-        return '<UNSET>'
-
-
-UNSET = Unset()
+    Ex: a.c.foo -> [a.c.foo, c.foo, foo]"""
+    while hostname:
+        yield hostname
+        hostname = hostname.partition(".")[-1]
 
 
 class ScopedValue:
@@ -213,7 +209,7 @@ class Values:
         if fallback:
             return self.opt.default
         else:
-            return UNSET
+            return usertypes.UNSET
 
     def get_for_url(self, url: QUrl = None, *,
                     fallback: bool = True) -> typing.Any:
@@ -222,14 +218,14 @@ class Values:
         This first tries to find a value matching the URL (if given).
         If there's no match:
           With fallback=True, the global/default setting is returned.
-          With fallback=False, UNSET is returned.
+          With fallback=False, usertypes.UNSET is returned.
         """
         self._check_pattern_support(url)
         if url is None:
             return self._get_fallback(fallback)
 
         candidates = []  # type: typing.List[ScopedValue]
-        widened_hosts = urlutils.widened_hostnames(url.host())
+        widened_hosts = _widened_hostnames(url.host())
         # We must check the 'None' key as well, in case any patterns that
         # did not have a domain match.
         for host in itertools.chain(widened_hosts, [None]):
@@ -243,7 +239,7 @@ class Values:
             return scoped.value
 
         if not fallback:
-            return UNSET
+            return usertypes.UNSET
 
         return self._get_fallback(fallback)
 
@@ -256,7 +252,7 @@ class Values:
 
         If there's no match:
           With fallback=True, the global/default setting is returned.
-          With fallback=False, UNSET is returned.
+          With fallback=False, usertypes.UNSET is returned.
         """
         self._check_pattern_support(pattern)
         if pattern is not None:
@@ -264,6 +260,6 @@ class Values:
                 return self._vmap[pattern].value
 
             if not fallback:
-                return UNSET
+                return usertypes.UNSET
 
         return self._get_fallback(fallback)
diff --git a/qutebrowser/config/stylesheet.py b/qutebrowser/config/stylesheet.py
new file mode 100644
index 000000000..27432d01b
--- /dev/null
+++ b/qutebrowser/config/stylesheet.py
@@ -0,0 +1,116 @@
+# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
+
+# Copyright 2019 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
+#
+# This file is part of qutebrowser.
+#
+# qutebrowser is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# qutebrowser is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Handling of Qt qss stylesheets."""
+
+import functools
+from typing import Optional, FrozenSet
+
+from PyQt5.QtCore import pyqtSlot, QObject
+
+from qutebrowser.config import config
+from qutebrowser.misc import debugcachestats
+from qutebrowser.utils import jinja, log
+
+
+def set_register(obj: QObject,
+                 stylesheet: str = None, *,
+                 update: bool = True) -> None:
+    """Set the stylesheet for an object.
+
+    Also, register an update when the config is changed.
+
+    Args:
+        obj: The object to set the stylesheet for and register.
+             Must have a STYLESHEET attribute if stylesheet is not given.
+        stylesheet: The stylesheet to use.
+        update: Whether to update the stylesheet on config changes.
+    """
+    observer = _StyleSheetObserver(obj, stylesheet, update)
+    observer.register()
+
+
+@debugcachestats.register()
+@functools.lru_cache()
+def _render_stylesheet(stylesheet: str) -> str:
+    """Render the given stylesheet jinja template."""
+    with jinja.environment.no_autoescape():
+        template = jinja.environment.from_string(stylesheet)
+    return template.render(conf=config.val)
+
+
+def init() -> None:
+    config.instance.changed.connect(_render_stylesheet.cache_clear)
+
+
+class _StyleSheetObserver(QObject):
+
+    """Set the stylesheet on the given object and update it on changes.
+
+    Attributes:
+        _obj: The object to observe.
+        _stylesheet: The stylesheet template to use.
+        _options: The config options that the stylesheet uses. When it's not
+                  necessary to listen for config changes, this attribute may be
+                  None.
+    """
+
+    def __init__(self, obj: QObject,
+                 stylesheet: Optional[str], update: bool) -> None:
+        super().__init__()
+        self._obj = obj
+        self._update = update
+
+        # We only need to hang around if we are asked to update.
+        if update:
+            self.setParent(self._obj)
+        if stylesheet is None:
+            self._stylesheet = obj.STYLESHEET  # type: str
+        else:
+            self._stylesheet = stylesheet
+
+        if update:
+            self._options = jinja.template_config_variables(
+                self._stylesheet)  # type: Optional[FrozenSet[str]]
+        else:
+            self._options = None
+
+    def _get_stylesheet(self) -> str:
+        """Format a stylesheet based on a template.
+
+        Return:
+            The formatted template as string.
+        """
+        return _render_stylesheet(self._stylesheet)
+
+    @pyqtSlot(str)
+    def _maybe_update_stylesheet(self, option: str) -> None:
+        """Update the stylesheet for obj if the option changed affects it."""
+        assert self._options is not None
+        if option in self._options:
+            self._obj.setStyleSheet(self._get_stylesheet())
+
+    def register(self) -> None:
+        """Do a first update and listen for more."""
+        qss = self._get_stylesheet()
+        log.config.vdebug(  # type: ignore
+            "stylesheet for {}: {}".format(self._obj.__class__.__name__, qss))
+        self._obj.setStyleSheet(qss)
+        if self._update:
+            config.instance.changed.connect(self._maybe_update_stylesheet)
diff --git a/qutebrowser/config/websettings.py b/qutebrowser/config/websettings.py
index 7b839a009..2f78b561e 100644
--- a/qutebrowser/config/websettings.py
+++ b/qutebrowser/config/websettings.py
@@ -29,7 +29,7 @@ from PyQt5.QtCore import QUrl, pyqtSlot, qVersion
 from PyQt5.QtGui import QFont
 
 import qutebrowser
-from qutebrowser.config import config, configutils
+from qutebrowser.config import config
 from qutebrowser.utils import log, usertypes, urlmatch, qtutils
 from qutebrowser.misc import objects, debugcachestats
 
@@ -106,7 +106,7 @@ class AbstractSettings:
     def set_attribute(self, name: str, value: typing.Any) -> bool:
         """Set the given QWebSettings/QWebEngineSettings attribute.
 
-        If the value is configutils.UNSET, the value is reset instead.
+        If the value is usertypes.UNSET, the value is reset instead.
 
         Return:
             True if there was a change, False otherwise.
@@ -115,7 +115,7 @@ class AbstractSettings:
 
         info = self._ATTRIBUTES[name]
         for attribute in info.attributes:
-            if value is configutils.UNSET:
+            if value is usertypes.UNSET:
                 self._settings.resetAttribute(attribute)
                 new_value = self.test_attribute(name)
             else:
@@ -139,7 +139,7 @@ class AbstractSettings:
         Return:
             True if there was a change, False otherwise.
         """
-        assert value is not configutils.UNSET  # type: ignore
+        assert value is not usertypes.UNSET  # type: ignore
         family = self._FONT_SIZES[name]
         old_value = self._settings.fontSize(family)
         self._settings.setFontSize(family, value)
@@ -154,7 +154,7 @@ class AbstractSettings:
         Return:
             True if there was a change, False otherwise.
         """
-        assert value is not configutils.UNSET  # type: ignore
+        assert value is not usertypes.UNSET  # type: ignore
         family = self._FONT_FAMILIES[name]
         if value is None:
             font = QFont()
@@ -172,7 +172,7 @@ class AbstractSettings:
         Return:
             True if there was a change, False otherwise.
         """
-        assert encoding is not configutils.UNSET  # type: ignore
+        assert encoding is not usertypes.UNSET  # type: ignore
         old_value = self._settings.defaultTextEncoding()
         self._settings.setDefaultTextEncoding(encoding)
         return old_value != encoding
diff --git a/qutebrowser/mainwindow/mainwindow.py b/qutebrowser/mainwindow/mainwindow.py
index ac5df12e6..e0f047bfb 100644
--- a/qutebrowser/mainwindow/mainwindow.py
+++ b/qutebrowser/mainwindow/mainwindow.py
@@ -31,7 +31,7 @@ from PyQt5.QtWidgets import QWidget, QVBoxLayout, QApplication, QSizePolicy
 
 from qutebrowser.commands import runners
 from qutebrowser.api import cmdutils
-from qutebrowser.config import config, configfiles
+from qutebrowser.config import config, configfiles, stylesheet
 from qutebrowser.utils import (message, log, usertypes, qtutils, objreg, utils,
                                jinja, debug)
 from qutebrowser.mainwindow import messageview, prompt
@@ -269,7 +269,7 @@ class MainWindow(QWidget):
         self._set_decoration(config.val.window.hide_decoration)
 
         self.state_before_fullscreen = self.windowState()
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
 
     def _init_geometry(self, geometry):
         """Initialize the window geometry or load it from disk."""
diff --git a/qutebrowser/mainwindow/messageview.py b/qutebrowser/mainwindow/messageview.py
index ea14265aa..3660d3529 100644
--- a/qutebrowser/mainwindow/messageview.py
+++ b/qutebrowser/mainwindow/messageview.py
@@ -24,7 +24,7 @@ import typing
 from PyQt5.QtCore import pyqtSlot, pyqtSignal, QTimer, Qt, QSize
 from PyQt5.QtWidgets import QWidget, QVBoxLayout, QLabel, QSizePolicy
 
-from qutebrowser.config import config
+from qutebrowser.config import config, stylesheet
 from qutebrowser.utils import usertypes
 
 
@@ -36,19 +36,19 @@ class Message(QLabel):
         super().__init__(text, parent)
         self.replace = replace
         self.setAttribute(Qt.WA_StyledBackground, True)
-        stylesheet = """
+        qss = """
             padding-top: 2px;
             padding-bottom: 2px;
         """
         if level == usertypes.MessageLevel.error:
-            stylesheet += """
+            qss += """
                 background-color: {{ conf.colors.messages.error.bg }};
                 color: {{ conf.colors.messages.error.fg }};
                 font: {{ conf.fonts.messages.error }};
                 border-bottom: 1px solid {{ conf.colors.messages.error.border }};
             """
         elif level == usertypes.MessageLevel.warning:
-            stylesheet += """
+            qss += """
                 background-color: {{ conf.colors.messages.warning.bg }};
                 color: {{ conf.colors.messages.warning.fg }};
                 font: {{ conf.fonts.messages.warning }};
@@ -56,7 +56,7 @@ class Message(QLabel):
                     1px solid {{ conf.colors.messages.warning.border }};
             """
         elif level == usertypes.MessageLevel.info:
-            stylesheet += """
+            qss += """
                 background-color: {{ conf.colors.messages.info.bg }};
                 color: {{ conf.colors.messages.info.fg }};
                 font: {{ conf.fonts.messages.info }};
@@ -66,8 +66,7 @@ class Message(QLabel):
             raise ValueError("Invalid level {!r}".format(level))
         # We don't bother with set_register_stylesheet here as it's short-lived
         # anyways.
-        config.set_register_stylesheet(self, stylesheet=stylesheet,
-                                       update=False)
+        stylesheet.set_register(self, qss, update=False)
 
 
 class MessageView(QWidget):
diff --git a/qutebrowser/mainwindow/prompt.py b/qutebrowser/mainwindow/prompt.py
index 6f7d1b9f7..ba6ff2f1b 100644
--- a/qutebrowser/mainwindow/prompt.py
+++ b/qutebrowser/mainwindow/prompt.py
@@ -33,7 +33,7 @@ from PyQt5.QtWidgets import (QWidget, QGridLayout, QVBoxLayout, QLineEdit,
                              QSpacerItem)
 
 from qutebrowser.browser import downloads
-from qutebrowser.config import config, configtypes, configexc
+from qutebrowser.config import config, configtypes, configexc, stylesheet
 from qutebrowser.utils import usertypes, log, utils, qtutils, objreg, message
 from qutebrowser.keyinput import modeman
 from qutebrowser.api import cmdutils
@@ -292,7 +292,7 @@ class PromptContainer(QWidget):
 
         self.setObjectName('PromptContainer')
         self.setAttribute(Qt.WA_StyledBackground, True)
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
 
         message.global_bridge.prompt_done.connect(self._on_prompt_done)
         prompt_queue.show_prompts.connect(self._on_show_prompts)
diff --git a/qutebrowser/mainwindow/statusbar/bar.py b/qutebrowser/mainwindow/statusbar/bar.py
index 463e0c151..dd50024b3 100644
--- a/qutebrowser/mainwindow/statusbar/bar.py
+++ b/qutebrowser/mainwindow/statusbar/bar.py
@@ -25,7 +25,7 @@ from PyQt5.QtCore import pyqtSignal, pyqtSlot, pyqtProperty, Qt, QSize, QTimer
 from PyQt5.QtWidgets import QWidget, QHBoxLayout, QStackedLayout, QSizePolicy
 
 from qutebrowser.browser import browsertab
-from qutebrowser.config import config
+from qutebrowser.config import config, stylesheet
 from qutebrowser.keyinput import modeman
 from qutebrowser.utils import usertypes, log, objreg, utils
 from qutebrowser.mainwindow.statusbar import (backforward, command, progress,
@@ -97,7 +97,7 @@ def _generate_stylesheet():
         ('passthrough', 'statusbar.passthrough'),
         ('private-command', 'statusbar.command.private'),
     ]
-    stylesheet = """
+    qss = """
         QWidget#StatusBar,
         QWidget#StatusBar QLabel,
         QWidget#StatusBar QLineEdit {
@@ -110,7 +110,7 @@ def _generate_stylesheet():
         }
     """
     for flag, option in flags:
-        stylesheet += """
+        qss += """
             QWidget#StatusBar[color_flags~="%s"],
             QWidget#StatusBar[color_flags~="%s"] QLabel,
             QWidget#StatusBar[color_flags~="%s"] QLineEdit {
@@ -122,7 +122,7 @@ def _generate_stylesheet():
             }
         """ % (flag, flag, flag,  # noqa: S001
                option + '.fg', flag, option + '.bg')
-    return stylesheet
+    return qss
 
 
 class StatusBar(QWidget):
@@ -158,7 +158,7 @@ class StatusBar(QWidget):
         super().__init__(parent)
         self.setObjectName(self.__class__.__name__)
         self.setAttribute(Qt.WA_StyledBackground)
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
 
         self.setSizePolicy(QSizePolicy.Ignored, QSizePolicy.Fixed)
 
@@ -298,7 +298,7 @@ class StatusBar(QWidget):
                 # Turning on is handled in on_current_caret_selection_toggled
                 log.statusbar.debug("Setting caret mode off")
                 self._color_flags.caret = ColorFlags.CaretMode.off
-        config.set_register_stylesheet(self, update=False)
+        stylesheet.set_register(self, update=False)
 
     def _set_mode_text(self, mode):
         """Set the mode text."""
@@ -382,7 +382,7 @@ class StatusBar(QWidget):
         else:
             self._set_mode_text("caret")
             self._color_flags.caret = ColorFlags.CaretMode.on
-        config.set_register_stylesheet(self, update=False)
+        stylesheet.set_register(self, update=False)
 
     def resizeEvent(self, e):
         """Extend resizeEvent of QWidget to emit a resized signal afterwards.
diff --git a/qutebrowser/mainwindow/statusbar/progress.py b/qutebrowser/mainwindow/statusbar/progress.py
index 34c1954e8..389ddf12e 100644
--- a/qutebrowser/mainwindow/statusbar/progress.py
+++ b/qutebrowser/mainwindow/statusbar/progress.py
@@ -22,7 +22,7 @@
 from PyQt5.QtCore import pyqtSlot, QSize
 from PyQt5.QtWidgets import QProgressBar, QSizePolicy
 
-from qutebrowser.config import config
+from qutebrowser.config import stylesheet
 from qutebrowser.utils import utils, usertypes
 
 
@@ -45,7 +45,7 @@ class Progress(QProgressBar):
 
     def __init__(self, parent=None):
         super().__init__(parent)
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
         self.enabled = False
         self.setSizePolicy(QSizePolicy.Fixed, QSizePolicy.Fixed)
         self.setTextVisible(False)
diff --git a/qutebrowser/mainwindow/statusbar/url.py b/qutebrowser/mainwindow/statusbar/url.py
index d6aacb184..7a84b1e4e 100644
--- a/qutebrowser/mainwindow/statusbar/url.py
+++ b/qutebrowser/mainwindow/statusbar/url.py
@@ -24,7 +24,7 @@ import enum
 from PyQt5.QtCore import pyqtSlot, pyqtProperty, QUrl
 
 from qutebrowser.mainwindow.statusbar import textbase
-from qutebrowser.config import config
+from qutebrowser.config import stylesheet
 from qutebrowser.utils import usertypes, urlutils
 
 
@@ -76,7 +76,7 @@ class UrlText(textbase.TextBase):
         super().__init__(parent)
         self._urltype = None
         self.setObjectName(self.__class__.__name__)
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
         self._hover_url = None
         self._normal_url = None
         self._normal_url_type = UrlType.normal
diff --git a/qutebrowser/mainwindow/tabwidget.py b/qutebrowser/mainwindow/tabwidget.py
index ba6ffb79f..6e3c00aad 100644
--- a/qutebrowser/mainwindow/tabwidget.py
+++ b/qutebrowser/mainwindow/tabwidget.py
@@ -32,7 +32,7 @@ from PyQt5.QtWidgets import (QTabWidget, QTabBar, QSizePolicy, QCommonStyle,
 from PyQt5.QtGui import QIcon, QPalette, QColor
 
 from qutebrowser.utils import qtutils, objreg, utils, usertypes, log
-from qutebrowser.config import config
+from qutebrowser.config import config, stylesheet
 from qutebrowser.misc import objects, debugcachestats
 from qutebrowser.browser import browsertab
 
@@ -400,7 +400,7 @@ class TabBar(QTabBar):
         self._on_show_switching_delay_changed()
         self.setAutoFillBackground(True)
         self.drag_in_progress = False
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
         QTimer.singleShot(0, self.maybe_hide)
 
     def __repr__(self):
diff --git a/qutebrowser/misc/keyhintwidget.py b/qutebrowser/misc/keyhintwidget.py
index 9cc00c6a8..68f9685d3 100644
--- a/qutebrowser/misc/keyhintwidget.py
+++ b/qutebrowser/misc/keyhintwidget.py
@@ -31,7 +31,7 @@ import re
 from PyQt5.QtWidgets import QLabel, QSizePolicy
 from PyQt5.QtCore import pyqtSlot, pyqtSignal, Qt
 
-from qutebrowser.config import config
+from qutebrowser.config import config, stylesheet
 from qutebrowser.utils import utils, usertypes
 from qutebrowser.misc import objects
 from qutebrowser.keyinput import keyutils
@@ -72,7 +72,7 @@ class KeyHintView(QLabel):
         self._show_timer = usertypes.Timer(self, 'keyhint_show')
         self._show_timer.timeout.connect(self.show)
         self._show_timer.setSingleShot(True)
-        config.set_register_stylesheet(self)
+        stylesheet.set_register(self)
 
     def __repr__(self):
         return utils.get_repr(self, win_id=self._win_id)
diff --git a/qutebrowser/utils/javascript.py b/qutebrowser/utils/javascript.py
index f456d93c9..2c02975db 100644
--- a/qutebrowser/utils/javascript.py
+++ b/qutebrowser/utils/javascript.py
@@ -21,8 +21,6 @@
 
 import typing
 
-from qutebrowser.utils import jinja
-
 _InnerJsArgType = typing.Union[None, str, bool, int, float]
 _JsArgType = typing.Union[_InnerJsArgType, typing.Sequence[_InnerJsArgType]]
 
@@ -83,5 +81,6 @@ def assemble(module: str, function: str, *args: _JsArgType) -> str:
 
 def wrap_global(name: str, *sources: str) -> str:
     """Wrap a script using window._qutebrowser."""
+    from qutebrowser.utils import jinja  # circular import
     template = jinja.js_environment.get_template('global_wrapper.js')
     return template.render(code='\n'.join(sources), name=name)
diff --git a/qutebrowser/utils/urlutils.py b/qutebrowser/utils/urlutils.py
index 51f0fd6cc..2908327dd 100644
--- a/qutebrowser/utils/urlutils.py
+++ b/qutebrowser/utils/urlutils.py
@@ -617,12 +617,3 @@ def proxy_from_url(url: QUrl) -> QNetworkProxy:
     if url.password():
         proxy.setPassword(url.password())
     return proxy
-
-
-def widened_hostnames(hostname: str) -> typing.Iterable[str]:
-    """A generator for widening string hostnames.
-
-    Ex: a.c.foo -> [a.c.foo, c.foo, foo]"""
-    while hostname:
-        yield hostname
-        hostname = hostname.partition(".")[-1]
diff --git a/qutebrowser/utils/usertypes.py b/qutebrowser/utils/usertypes.py
index 58fe950b2..65ab2d491 100644
--- a/qutebrowser/utils/usertypes.py
+++ b/qutebrowser/utils/usertypes.py
@@ -33,14 +33,17 @@ from qutebrowser.utils import log, qtutils, utils
 _T = typing.TypeVar('_T')
 
 
-class UnsetObject:
+class Unset:
 
     """Class for an unset object."""
 
     __slots__ = ()
 
+    def __repr__(self) -> str:
+        return '<UNSET>'
+
 
-UNSET = UnsetObject()
+UNSET = Unset()
 
 
 class NeighborList(typing.Sequence[_T]):
@@ -60,7 +63,7 @@ class NeighborList(typing.Sequence[_T]):
     Modes = enum.Enum('Modes', ['edge', 'exception'])
 
     def __init__(self, items: typing.Sequence[_T] = None,
-                 default: typing.Union[_T, UnsetObject] = UNSET,
+                 default: typing.Union[_T, Unset] = UNSET,
                  mode: Modes = Modes.exception) -> None:
         """Constructor.
 
@@ -79,7 +82,7 @@ class NeighborList(typing.Sequence[_T]):
             self._items = list(items)
         self._default = default
 
-        if not isinstance(default, UnsetObject):
+        if not isinstance(default, Unset):
             idx = self._items.index(default)
             self._idx = idx  # type: typing.Optional[int]
         else:
diff --git a/tests/helpers/fixtures.py b/tests/helpers/fixtures.py
index 880438d93..045be5e94 100644
--- a/tests/helpers/fixtures.py
+++ b/tests/helpers/fixtures.py
@@ -43,7 +43,7 @@ from PyQt5.QtNetwork import QNetworkCookieJar
 
 import helpers.stubs as stubsmod
 from qutebrowser.config import (config, configdata, configtypes, configexc,
-                                configfiles, configcache)
+                                configfiles, configcache, stylesheet)
 from qutebrowser.api import config as configapi
 from qutebrowser.utils import objreg, standarddir, utils, usertypes
 from qutebrowser.browser import greasemonkey, history, qutescheme
@@ -319,6 +319,9 @@ def config_stub(stubs, monkeypatch, configdata_init, yaml_config_stub):
         pass
 
     conf.val = container  # For easier use in tests
+
+    stylesheet.init()
+
     return conf
 
 
diff --git a/tests/unit/config/test_config.py b/tests/unit/config/test_config.py
index 9eefedf15..d81cb91dd 100644
--- a/tests/unit/config/test_config.py
+++ b/tests/unit/config/test_config.py
@@ -23,10 +23,10 @@ import unittest.mock
 import functools
 
 import pytest
-from PyQt5.QtCore import QObject, QUrl
+from PyQt5.QtCore import QUrl
 from PyQt5.QtGui import QColor
 
-from qutebrowser.config import config, configdata, configexc, configutils
+from qutebrowser.config import config, configdata, configexc
 from qutebrowser.utils import usertypes, urlmatch
 from qutebrowser.misc import objects
 from qutebrowser.keyinput import keyutils
@@ -410,7 +410,7 @@ class TestConfig:
 
         assert conf.get(name) == 'always'
         if save_yaml:
-            assert yaml_value(name) is configutils.UNSET
+            assert yaml_value(name) is usertypes.UNSET
         else:
             assert yaml_value(name) == 'never'
 
@@ -439,8 +439,8 @@ class TestConfig:
         assert options == {name1, name2}
 
         if save_yaml:
-            assert yaml_value(name1) is configutils.UNSET
-            assert yaml_value(name2) is configutils.UNSET
+            assert yaml_value(name1) is usertypes.UNSET
+            assert yaml_value(name2) is usertypes.UNSET
         else:
             assert yaml_value(name1) == 'never'
             assert yaml_value(name2) is True
@@ -482,7 +482,7 @@ class TestConfig:
 
     @pytest.mark.parametrize('fallback, expected', [
         (True, True),
-        (False, configutils.UNSET)
+        (False, usertypes.UNSET)
     ])
     def test_get_for_url_fallback(self, conf, fallback, expected):
         """Test conf.get() with a URL and fallback."""
@@ -617,7 +617,7 @@ class TestConfig:
         pattern = urlmatch.UrlPattern('*://example.com')
         name = 'content.javascript.enabled'
         value = conf.get_obj_for_pattern(name, pattern=pattern)
-        assert value is configutils.UNSET
+        assert value is usertypes.UNSET
 
     def test_get_str(self, conf):
         assert conf.get_str('content.plugins') == 'false'
@@ -637,7 +637,7 @@ class TestConfig:
         if save_yaml:
             assert yaml_value(option) is True
         else:
-            assert yaml_value(option) is configutils.UNSET
+            assert yaml_value(option) is usertypes.UNSET
 
     @pytest.mark.parametrize('method', ['set_obj', 'set_str'])
     def test_set_invalid(self, conf, qtbot, method):
@@ -669,7 +669,7 @@ class TestConfig:
                 meth(option, value, save_yaml=True)
 
         assert not conf._values[option]
-        assert yaml_value(option) is configutils.UNSET
+        assert yaml_value(option) is usertypes.UNSET
 
     @pytest.mark.parametrize('method, value', [
         ('set_obj', {}),
@@ -766,57 +766,3 @@ class TestContainer:
         with pytest.raises(TypeError,
                            match="Can't use pattern without configapi!"):
             config.ConfigContainer(config_stub, pattern=pattern)
-
-
-class StyleObj(QObject):
-
-    def __init__(self, stylesheet=None, parent=None):
-        super().__init__(parent)
-        if stylesheet is not None:
-            self.STYLESHEET = stylesheet  # noqa: N801,N806 pylint: disable=invalid-name
-        self.rendered_stylesheet = None
-
-    def setStyleSheet(self, stylesheet):
-        self.rendered_stylesheet = stylesheet
-
-
-def test_get_stylesheet(config_stub):
-    config_stub.val.colors.hints.fg = 'magenta'
-    observer = config.StyleSheetObserver(
-        StyleObj(), stylesheet="{{ conf.colors.hints.fg }}", update=False)
-    assert observer._get_stylesheet() == 'magenta'
-
-
-@pytest.mark.parametrize('delete', [True, False])
-@pytest.mark.parametrize('stylesheet_param', [True, False])
-@pytest.mark.parametrize('update', [True, False])
-def test_set_register_stylesheet(delete, stylesheet_param, update, qtbot,
-                                 config_stub, caplog):
-    config_stub.val.colors.hints.fg = 'magenta'
-    stylesheet = "{{ conf.colors.hints.fg }}"
-
-    with caplog.at_level(9):  # VDEBUG
-        if stylesheet_param:
-            obj = StyleObj()
-            config.set_register_stylesheet(obj, stylesheet=stylesheet,
-                                           update=update)
-        else:
-            obj = StyleObj(stylesheet)
-            config.set_register_stylesheet(obj, update=update)
-
-    assert caplog.messages[-1] == 'stylesheet for StyleObj: magenta'
-
-    assert obj.rendered_stylesheet == 'magenta'
-
-    if delete:
-        with qtbot.waitSignal(obj.destroyed):
-            obj.deleteLater()
-
-    config_stub.val.colors.hints.fg = 'yellow'
-
-    if delete or not update:
-        expected = 'magenta'
-    else:
-        expected = 'yellow'
-
-    assert obj.rendered_stylesheet == expected
diff --git a/tests/unit/config/test_configcommands.py b/tests/unit/config/test_configcommands.py
index 382d41ad8..97dcd7c42 100644
--- a/tests/unit/config/test_configcommands.py
+++ b/tests/unit/config/test_configcommands.py
@@ -25,7 +25,7 @@ import unittest.mock
 import pytest
 from PyQt5.QtCore import QUrl
 
-from qutebrowser.config import configcommands, configutils
+from qutebrowser.config import configcommands
 from qutebrowser.api import cmdutils
 from qutebrowser.utils import usertypes, urlmatch
 from qutebrowser.keyinput import keyutils
@@ -92,7 +92,7 @@ class TestSet:
         commands.set(0, option, inp, temp=temp)
 
         assert config_stub.get(option) == new_value
-        assert yaml_value(option) == (configutils.UNSET if temp else new_value)
+        assert yaml_value(option) == (usertypes.UNSET if temp else new_value)
 
     def test_set_with_pattern(self, monkeypatch, commands, config_stub):
         monkeypatch.setattr(objects, 'backend', usertypes.Backend.QtWebKit)
@@ -295,7 +295,7 @@ class TestAdd:
 
         assert str(config_stub.get(name)[-1]) == value
         if temp:
-            assert yaml_value(name) == configutils.UNSET
+            assert yaml_value(name) == usertypes.UNSET
         else:
             assert yaml_value(name)[-1] == value
 
@@ -328,7 +328,7 @@ class TestAdd:
 
         assert str(config_stub.get(name)[key]) == value
         if temp:
-            assert yaml_value(name) == configutils.UNSET
+            assert yaml_value(name) == usertypes.UNSET
         else:
             assert yaml_value(name)[key] == value
 
@@ -379,7 +379,7 @@ class TestRemove:
 
         assert value not in config_stub.get(name)
         if temp:
-            assert yaml_value(name) == configutils.UNSET
+            assert yaml_value(name) == usertypes.UNSET
         else:
             assert value not in yaml_value(name)
 
@@ -410,7 +410,7 @@ class TestRemove:
 
         assert key not in config_stub.get(name)
         if temp:
-            assert yaml_value(name) == configutils.UNSET
+            assert yaml_value(name) == usertypes.UNSET
         else:
             assert key not in yaml_value(name)
 
@@ -446,7 +446,7 @@ class TestUnsetAndClear:
         commands.config_unset(name, temp=temp)
 
         assert config_stub.get(name) == 'always'
-        assert yaml_value(name) == ('never' if temp else configutils.UNSET)
+        assert yaml_value(name) == ('never' if temp else usertypes.UNSET)
 
     def test_unset_unknown_option(self, commands):
         with pytest.raises(cmdutils.CommandError, match="No option 'tabs'"):
@@ -460,7 +460,7 @@ class TestUnsetAndClear:
         commands.config_clear(save=save)
 
         assert config_stub.get(name) == 'always'
-        assert yaml_value(name) == (configutils.UNSET if save else 'never')
+        assert yaml_value(name) == (usertypes.UNSET if save else 'never')
 
 
 class TestSource:
diff --git a/tests/unit/config/test_configtypes.py b/tests/unit/config/test_configtypes.py
index 55d225a7e..e766fca8a 100644
--- a/tests/unit/config/test_configtypes.py
+++ b/tests/unit/config/test_configtypes.py
@@ -34,8 +34,8 @@ from PyQt5.QtGui import QColor, QFont
 from PyQt5.QtNetwork import QNetworkProxy
 
 from qutebrowser.misc import objects
-from qutebrowser.config import configtypes, configexc, configutils
-from qutebrowser.utils import debug, utils, qtutils, urlmatch
+from qutebrowser.config import configtypes, configexc
+from qutebrowser.utils import debug, utils, qtutils, urlmatch, usertypes
 from qutebrowser.browser.network import pac
 from qutebrowser.keyinput import keyutils
 from helpers import utils as testutils
@@ -277,7 +277,7 @@ class TestAll:
     @pytest.mark.parametrize('none_ok', [True, False])
     def test_unset(self, klass, none_ok):
         typ = klass(none_ok=none_ok)
-        assert typ.to_py(configutils.UNSET) is configutils.UNSET
+        assert typ.to_py(usertypes.UNSET) is usertypes.UNSET
 
     def test_to_str_none(self, klass):
         assert klass().to_str(None) == ''
diff --git a/tests/unit/config/test_configutils.py b/tests/unit/config/test_configutils.py
index 8cdee2081..2c99ec34b 100644
--- a/tests/unit/config/test_configutils.py
+++ b/tests/unit/config/test_configutils.py
@@ -23,19 +23,10 @@ import pytest
 from PyQt5.QtCore import QUrl
 
 from qutebrowser.config import configutils, configdata, configtypes
-from qutebrowser.utils import urlmatch
+from qutebrowser.utils import urlmatch, usertypes
 from tests.helpers import utils
 
 
-def test_unset_object_identity():
-    assert configutils.Unset() is not configutils.Unset()
-    assert configutils.UNSET is configutils.UNSET
-
-
-def test_unset_object_repr():
-    assert repr(configutils.UNSET) == '<UNSET>'
-
-
 @pytest.fixture
 def opt():
     return configdata.Option(name='example.option', typ=configtypes.String(),
@@ -146,7 +137,7 @@ def test_clear(values):
     assert values
     values.clear()
     assert not values
-    assert values.get_for_url(fallback=False) is configutils.UNSET
+    assert values.get_for_url(fallback=False) is usertypes.UNSET
 
 
 def test_get_matching(values):
@@ -155,12 +146,12 @@ def test_get_matching(values):
 
 
 def test_get_unset(empty_values):
-    assert empty_values.get_for_url(fallback=False) is configutils.UNSET
+    assert empty_values.get_for_url(fallback=False) is usertypes.UNSET
 
 
 def test_get_no_global(empty_values, other_pattern, pattern):
     empty_values.add('example.org value', pattern)
-    assert empty_values.get_for_url(fallback=False) is configutils.UNSET
+    assert empty_values.get_for_url(fallback=False) is usertypes.UNSET
 
 
 def test_get_unset_fallback(empty_values):
@@ -169,7 +160,7 @@ def test_get_unset_fallback(empty_values):
 
 def test_get_non_matching(values):
     url = QUrl('https://www.example.ch/')
-    assert values.get_for_url(url, fallback=False) is configutils.UNSET
+    assert values.get_for_url(url, fallback=False) is usertypes.UNSET
 
 
 def test_get_non_matching_fallback(values):
@@ -205,13 +196,13 @@ def test_get_pattern_none(values, pattern):
 
 def test_get_unset_pattern(empty_values, pattern):
     value = empty_values.get_for_pattern(pattern, fallback=False)
-    assert value is configutils.UNSET
+    assert value is usertypes.UNSET
 
 
 def test_get_no_global_pattern(empty_values, pattern, other_pattern):
     empty_values.add('example.org value', other_pattern)
     value = empty_values.get_for_pattern(pattern, fallback=False)
-    assert value is configutils.UNSET
+    assert value is usertypes.UNSET
 
 
 def test_get_unset_fallback_pattern(empty_values, pattern):
@@ -220,7 +211,7 @@ def test_get_unset_fallback_pattern(empty_values, pattern):
 
 def test_get_non_matching_pattern(values, other_pattern):
     value = values.get_for_pattern(other_pattern, fallback=False)
-    assert value is configutils.UNSET
+    assert value is usertypes.UNSET
 
 
 def test_get_non_matching_fallback_pattern(values, other_pattern):
@@ -263,3 +254,26 @@ def test_domain_lookup_sparse_benchmark(url, values, benchmark):
             values.add(False, urlmatch.UrlPattern(line))
 
     benchmark(lambda: values.get_for_url(url))
+
+
+class TestWiden:
+
+    @pytest.mark.parametrize('hostname, expected', [
+        ('a.b.c', ['a.b.c', 'b.c', 'c']),
+        ('foobarbaz', ['foobarbaz']),
+        ('', []),
+        ('.c', ['.c', 'c']),
+        ('c.', ['c.']),
+        ('.c.', ['.c.', 'c.']),
+        (None, []),
+    ])
+    def test_widen_hostnames(self, hostname, expected):
+        assert list(configutils._widened_hostnames(hostname)) == expected
+
+    @pytest.mark.parametrize('hostname', [
+        'test.qutebrowser.org',
+        'a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.z.y.z',
+        'qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq.c',
+    ])
+    def test_bench_widen_hostnames(self, hostname, benchmark):
+        benchmark(lambda: list(configutils._widened_hostnames(hostname)))
diff --git a/tests/unit/config/test_stylesheet.py b/tests/unit/config/test_stylesheet.py
new file mode 100644
index 000000000..67bdd04b4
--- /dev/null
+++ b/tests/unit/config/test_stylesheet.py
@@ -0,0 +1,72 @@
+# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
+# Copyright 2019 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
+
+# This file is part of qutebrowser.
+#
+# qutebrowser is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# qutebrowser is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
+
+import pytest
+
+from PyQt5.QtCore import QObject
+
+from qutebrowser.config import stylesheet
+
+
+class StyleObj(QObject):
+
+    def __init__(self, stylesheet=None, parent=None):
+        super().__init__(parent)
+        if stylesheet is not None:
+            self.STYLESHEET = stylesheet  # noqa: N801,N806 pylint: disable=invalid-name
+        self.rendered_stylesheet = None
+
+    def setStyleSheet(self, stylesheet):
+        self.rendered_stylesheet = stylesheet
+
+
+def test_get_stylesheet(config_stub):
+    config_stub.val.colors.hints.fg = 'magenta'
+    observer = stylesheet._StyleSheetObserver(
+        StyleObj(), stylesheet="{{ conf.colors.hints.fg }}", update=False)
+    assert observer._get_stylesheet() == 'magenta'
+
+
+@pytest.mark.parametrize('delete', [True, False])
+@pytest.mark.parametrize('stylesheet_param', [True, False])
+@pytest.mark.parametrize('update', [True, False])
+def test_set_register_stylesheet(delete, stylesheet_param, update, qtbot,
+                                 config_stub, caplog):
+    config_stub.val.colors.hints.fg = 'magenta'
+    qss = "{{ conf.colors.hints.fg }}"
+
+    with caplog.at_level(9):  # VDEBUG
+        if stylesheet_param:
+            obj = StyleObj()
+            stylesheet.set_register(obj, qss, update=update)
+        else:
+            obj = StyleObj(qss)
+            stylesheet.set_register(obj, update=update)
+
+    assert caplog.messages[-1] == 'stylesheet for StyleObj: magenta'
+
+    assert obj.rendered_stylesheet == 'magenta'
+
+    if delete:
+        with qtbot.waitSignal(obj.destroyed):
+            obj.deleteLater()
+
+    config_stub.val.colors.hints.fg = 'yellow'
+
+    expected = 'magenta' if delete or not update else 'yellow'
+    assert obj.rendered_stylesheet == expected
diff --git a/tests/unit/javascript/stylesheet/test_stylesheet.py b/tests/unit/javascript/stylesheet/test_stylesheet_js.py
index 768ffaeb9..768ffaeb9 100644
--- a/tests/unit/javascript/stylesheet/test_stylesheet.py
+++ b/tests/unit/javascript/stylesheet/test_stylesheet_js.py
diff --git a/tests/unit/utils/test_urlutils.py b/tests/unit/utils/test_urlutils.py
index bf1ce47c8..b6d73319d 100644
--- a/tests/unit/utils/test_urlutils.py
+++ b/tests/unit/utils/test_urlutils.py
@@ -706,26 +706,3 @@ class TestProxyFromUrl:
     def test_invalid(self, url, exception):
         with pytest.raises(exception):
             urlutils.proxy_from_url(QUrl(url))
-
-
-class TestWiden:
-
-    @pytest.mark.parametrize('hostname, expected', [
-        ('a.b.c', ['a.b.c', 'b.c', 'c']),
-        ('foobarbaz', ['foobarbaz']),
-        ('', []),
-        ('.c', ['.c', 'c']),
-        ('c.', ['c.']),
-        ('.c.', ['.c.', 'c.']),
-        (None, []),
-    ])
-    def test_widen_hostnames(self, hostname, expected):
-        assert list(urlutils.widened_hostnames(hostname)) == expected
-
-    @pytest.mark.parametrize('hostname', [
-        'test.qutebrowser.org',
-        'a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.z.y.z',
-        'qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq.c',
-    ])
-    def test_bench_widen_hostnames(self, hostname, benchmark):
-        benchmark(lambda: list(urlutils.widened_hostnames(hostname)))
diff --git a/tests/unit/utils/usertypes/test_misc.py b/tests/unit/utils/usertypes/test_misc.py
index 1700b7f51..68eabc213 100644
--- a/tests/unit/utils/usertypes/test_misc.py
+++ b/tests/unit/utils/usertypes/test_misc.py
@@ -25,3 +25,12 @@ def test_abstract_certificate_error_wrapper():
     err = object()
     wrapper = usertypes.AbstractCertificateErrorWrapper(err)
     assert wrapper._error is err
+
+
+def test_unset_object_identity():
+    assert usertypes.Unset() is not usertypes.Unset()
+    assert usertypes.UNSET is usertypes.UNSET
+
+
+def test_unset_object_repr():
+    assert repr(usertypes.UNSET) == '<UNSET>'