diff --git a/cssutils/__init__.py b/cssutils/__init__.py
index 277704c1..38d22353 100644
--- a/cssutils/__init__.py
+++ b/cssutils/__init__.py
@@ -133,7 +133,7 @@ def createCSSStyleSheet(self, title, media):
             "https://web.archive.org/web/20200701035537/"
             "https://bitbucket.org/cthedot/cssutils/issues/69#comment-30669799"
         )
-        warnings.warn(warning, DeprecationWarning)
+        warnings.warn(warning, DeprecationWarning, stacklevel=2)
         return css.CSSStyleSheet(title=title, media=media)
 
     def createDocument(self, *args, **kwargs):
diff --git a/cssutils/css/cssrule.py b/cssutils/css/cssrule.py
index 2fd30adc..ff07f53d 100644
--- a/cssutils/css/cssrule.py
+++ b/cssutils/css/cssrule.py
@@ -174,7 +174,7 @@ def _setCssRules(self, cssRules):
         "Set new cssRules and update contained rules refs."
         cssRules.append = self.insertRule
         cssRules.extend = self.insertRule
-        cssRules.__delitem__ == self.deleteRule
+        cssRules.__delitem__ = self.deleteRule
 
         for rule in cssRules:
             rule._parentRule = self
@@ -225,12 +225,12 @@ def deleteRule(self, index):
             self._cssRules[index]._parentRule = None
             del self._cssRules[index]
 
-        except IndexError:
+        except IndexError as err:
             raise xml.dom.IndexSizeErr(
                 '%s: %s is not a valid index '
                 'in the rulelist of length %i'
                 % (self.__class__.__name__, index, self._cssRules.length)
-            )
+            ) from err
 
     def _prepareInsertRule(self, rule, index=None):
         "return checked `index` and optional parsed `rule`"
diff --git a/cssutils/css/cssstylesheet.py b/cssutils/css/cssstylesheet.py
index b4bc4c6b..e8c88a5b 100644
--- a/cssutils/css/cssstylesheet.py
+++ b/cssutils/css/cssstylesheet.py
@@ -526,11 +526,11 @@ def deleteRule(self, index):
 
         try:
             rule = self._cssRules[index]
-        except IndexError:
+        except IndexError as err:
             raise xml.dom.IndexSizeErr(
                 'CSSStyleSheet: %s is not a valid index in the rulelist of '
                 'length %i' % (index, self._cssRules.length)
-            )
+            ) from err
         else:
             if rule.type == rule.NAMESPACE_RULE:
                 # check all namespacerules if used
diff --git a/cssutils/css/cssvalue.py b/cssutils/css/cssvalue.py
index c88e7849..a386bd0d 100644
--- a/cssutils/css/cssvalue.py
+++ b/cssutils/css/cssvalue.py
@@ -560,9 +560,7 @@ def __init__(self, cssText=None, parent=None, readonly=False):
         super().__init__(cssText=cssText, parent=parent, readonly=readonly)
 
     def __str__(self):
-        return (
-            f"<cssutils.css.{self.__class__.__name__} object primitiveType={self.primitiveTypeString} cssText={self.cssText!r} at 0x{id(self):x}>"
-        )
+        return f"<cssutils.css.{self.__class__.__name__} object primitiveType={self.primitiveTypeString} cssText={self.cssText!r} at 0x{id(self):x}>"
 
     _unitnames = [
         'CSS_UNKNOWN',
@@ -696,10 +694,10 @@ def _getNumDim(self, value=None):
             val = float(val)
             if val == int(val):
                 val = int(val)
-        except ValueError:
+        except ValueError as err:
             raise xml.dom.InvalidAccessErr(
                 'CSSPrimitiveValue: No float value %r' % self._value[0]
-            )
+            ) from err
 
         return val, dim
 
@@ -731,14 +729,14 @@ def getFloatValue(self, unitType=None):
             # convert if needed
             try:
                 val = self._converter[self.primitiveType, unitType](val)
-            except KeyError:
+            except KeyError as err:
                 raise xml.dom.InvalidAccessErr(
                     'CSSPrimitiveValue: Cannot coerce primitiveType %r to %r'
                     % (
                         self.primitiveTypeString,
                         self._getCSSPrimitiveTypeString(unitType),
                     )
-                )
+                ) from err
 
         if val == int(val):
             val = int(val)
@@ -775,24 +773,24 @@ def setFloatValue(self, unitType, floatValue):
             )
         try:
             val = float(floatValue)
-        except ValueError:
+        except ValueError as err:
             raise xml.dom.InvalidAccessErr(
                 'CSSPrimitiveValue: floatValue %r is not a float' % floatValue
-            )
+            ) from err
 
         oldval, dim = self._getNumDim()
         if self.primitiveType != unitType:
             # convert if possible
             try:
                 val = self._converter[unitType, self.primitiveType](val)
-            except KeyError:
+            except KeyError as err:
                 raise xml.dom.InvalidAccessErr(
                     'CSSPrimitiveValue: Cannot coerce primitiveType %r to %r'
                     % (
                         self.primitiveTypeString,
                         self._getCSSPrimitiveTypeString(unitType),
                     )
-                )
+                ) from err
 
         if val == int(val):
             val = int(val)
diff --git a/cssutils/css2productions.py b/cssutils/css2productions.py
index 3eadb95c..9a1d59b7 100644
--- a/cssutils/css2productions.py
+++ b/cssutils/css2productions.py
@@ -127,5 +127,5 @@ class CSSProductions:
     pass
 
 
-for i, t in enumerate(PRODUCTIONS):
+for t in PRODUCTIONS:
     setattr(CSSProductions, t[0].replace('-', '_'), t[0])
diff --git a/cssutils/cssproductions.py b/cssutils/cssproductions.py
index 02541266..0cbba821 100644
--- a/cssutils/cssproductions.py
+++ b/cssutils/cssproductions.py
@@ -111,7 +111,7 @@ class CSSProductions:
     VARIABLES_SYM = 'VARIABLES_SYM'
 
 
-for i, t in enumerate(PRODUCTIONS):
+for t in PRODUCTIONS:
     setattr(CSSProductions, t[0].replace('-', '_'), t[0])
 
 
diff --git a/cssutils/prodparser.py b/cssutils/prodparser.py
index 4be27127..2d8f583f 100644
--- a/cssutils/prodparser.py
+++ b/cssutils/prodparser.py
@@ -329,7 +329,7 @@ def toStore(store, item):
         else:
             self.toSeq = lambda t, tokens: (t[0], t[1])
 
-        if hasattr(toStore, '__call__'):
+        if callable(toStore):
             self.toStore = toStore
         elif toStore:
             self.toStore = makeToStore(toStore)
diff --git a/cssutils/tests/test_cssrule.py b/cssutils/tests/test_cssrule.py
index be657de3..a7eab72b 100644
--- a/cssutils/tests/test_cssrule.py
+++ b/cssutils/tests/test_cssrule.py
@@ -98,12 +98,12 @@ def test(s):
         test(s)
         # sheet.add CSS
         s = cssutils.css.CSSStyleSheet()
-        for css, type_ in rules:
+        for css, _ in rules:
             s.add(css)
         test(s)
         # sheet.insertRule CSS
         s = cssutils.css.CSSStyleSheet()
-        for css, type_ in rules:
+        for css, _ in rules:
             s.insertRule(css)
         test(s)
 
@@ -120,14 +120,14 @@ def test(s):
         ]
         # sheet.add CSSRule
         s = cssutils.css.CSSStyleSheet()
-        for i, (css, type_) in enumerate(rules):
+        for i, (css, _) in enumerate(rules):
             rule = types[i]()
             rule.cssText = css
             s.add(rule)
         test(s)
         # sheet.insertRule CSSRule
         s = cssutils.css.CSSStyleSheet()
-        for i, (css, type_) in enumerate(rules):
+        for i, (css, _) in enumerate(rules):
             rule = types[i]()
             rule.cssText = css
             s.insertRule(rule)
@@ -165,12 +165,12 @@ def getMediaSheet():
 
         # sheet.add CSS
         s, mr = getMediaSheet()
-        for css, type_ in rules:
+        for css, _ in rules:
             mr.add(css)
         test(s)
         # sheet.insertRule CSS
         s, mr = getMediaSheet()
-        for css, type_ in rules:
+        for css, _ in rules:
             mr.insertRule(css)
         test(s)
 
@@ -181,14 +181,14 @@ def getMediaSheet():
         ]
         # sheet.add CSSRule
         s, mr = getMediaSheet()
-        for i, (css, type_) in enumerate(rules):
+        for i, (css, _) in enumerate(rules):
             rule = types[i]()
             rule.cssText = css
             mr.add(rule)
         test(s)
         # sheet.insertRule CSSRule
         s, mr = getMediaSheet()
-        for i, (css, type_) in enumerate(rules):
+        for i, (css, _) in enumerate(rules):
             rule = types[i]()
             rule.cssText = css
             mr.insertRule(rule)
diff --git a/cssutils/tests/test_cssstylesheet.py b/cssutils/tests/test_cssstylesheet.py
index 53285f05..0f33992f 100644
--- a/cssutils/tests/test_cssstylesheet.py
+++ b/cssutils/tests/test_cssstylesheet.py
@@ -84,7 +84,7 @@ def test_refs(self):
         ).cssRules
         # new object
         assert rules != s.cssRules
-        for i, r in enumerate(s.cssRules):
+        for r in s.cssRules:
             assert r.parentStyleSheet == s
 
         # namespaces
diff --git a/cssutils/tests/test_cssvalue.py b/cssutils/tests/test_cssvalue.py
index 8a3df4a6..5dbb0c5a 100644
--- a/cssutils/tests/test_cssvalue.py
+++ b/cssutils/tests/test_cssvalue.py
@@ -68,7 +68,7 @@ def test_cssText(self):
         assert v.CSS_VALUE_LIST == v.cssValueType
         assert 'normal 1px a, b, "c" end' == v.cssText
 
-        for i, x in enumerate(v):
+        for x in v:
             assert x.CSS_PRIMITIVE_VALUE == x.cssValueType
             if x == 0:
                 assert x.CSS_IDENT == x.primitiveType
diff --git a/cssutils/tests/test_prodparser.py b/cssutils/tests/test_prodparser.py
index cc9d2580..d3dff8d1 100644
--- a/cssutils/tests/test_prodparser.py
+++ b/cssutils/tests/test_prodparser.py
@@ -245,7 +245,7 @@ def test_nextProd(self):
         }
         for seqitems, results in list(tests.items()):
             for result in results:
-                seq = Sequence(minmax=lambda: (1, 2), *seqitems)
+                seq = Sequence(*seqitems, minmax=lambda: (1, 2))
                 for t, p in result:
                     if isinstance(p, str):
                         with pytest.raises(ParseError, match=re.escape(p)):
diff --git a/cssutils/tests/test_profiles.py b/cssutils/tests/test_profiles.py
index 8c42c67d..688ad9c0 100644
--- a/cssutils/tests/test_profiles.py
+++ b/cssutils/tests/test_profiles.py
@@ -688,7 +688,7 @@ def test_validate(self):
             ),
         }
         # TODO!!!
-        for (name, values), (valid, matching, profile) in list(tests.items()):
+        for (name, values), (valid, _matching, _profile) in list(tests.items()):
             for value in values:
                 assert valid == cssutils.profile.validate(name, value)
 
diff --git a/cssutils/tests/test_value.py b/cssutils/tests/test_value.py
index aa23de90..6cd0c999 100644
--- a/cssutils/tests/test_value.py
+++ b/cssutils/tests/test_value.py
@@ -709,7 +709,7 @@ def test_cssText(self):
             ),
             'var(C, #f00 )': ('var(C, #f00)', 'C', '#fff'),
         }
-        for var, (cssText, name, fallback) in list(tests.items()):
+        for var, (cssText, name, _fallback) in list(tests.items()):
             v = cssutils.css.CSSVariable(var)
             assert cssText == v.cssText
             assert 'VARIABLE' == v.type
diff --git a/tools/try.py b/tools/try.py
index d6f3167a..27c47c6f 100644
--- a/tools/try.py
+++ b/tools/try.py
@@ -130,7 +130,7 @@ def maketokens(valuelist):
 font-family : a  b;
 }
 '''
-    cssutils.parseString(s).cssText
+    cssutils.parseString(s).cssText  # noqa: B018
     sys.exit(1)
 
     import cssutils