diff --git a/.stylelintrc.yml b/.stylelintrc.yml
index f5b4fdcd..55daa5b6 100644
--- a/.stylelintrc.yml
+++ b/.stylelintrc.yml
@@ -9,6 +9,9 @@ plugins:
 
 rules:
 
+ # Specify percentage or number notation for alpha-values.
+  alpha-value-notation: number
+
   # Specify a blacklist of disallowed at-rules.
   at-rule-blacklist:
     - debug
@@ -89,6 +92,9 @@ rules:
   # Require a single space or disallow whitespace before the opening brace of blocks.
   block-opening-brace-space-before: always
 
+  # Specify modern or legacy notation for applicable color-functions.
+  color-function-notation: legacy
+
   # Specify lowercase or uppercase for hexadecimal color values.
   color-hex-case: lower
 
@@ -120,7 +126,7 @@ rules:
   #custom-media-pattern:
 
   # Require or disallow an empty line before custom properties (Autofixable).
-  custom-property-empty-line-before: never
+  custom-property-empty-line-before: always
 
   # Specify a pattern for custom properties.
   #custom-property-pattern:
@@ -254,6 +260,9 @@ rules:
   # Require or disallow whitespace after functions.
   function-whitespace-after: always
 
+  # Specify number or angle notation for degree hues.
+  hue-degree-notation: angle
+
   # Specify indentation.
   indentation: 4
 
@@ -1028,6 +1037,9 @@ rules:
   # Disallow unknown at-rules. Should be used instead of stylelint's `at-rule-no-unknown`.
   scss/at-rule-no-unknown: true
 
+  # Disallow empty comments.
+  scss/comment-no-empty: true
+
   # Require a newline after the colon in `$`-variable declarations.
   scss/dollar-variable-colon-newline-after: always-multi-line
 
@@ -1043,6 +1055,12 @@ rules:
   # Disallow duplicate dollar variables within a stylesheet.
   scss/no-duplicate-dollar-variables: true
 
+  # Disallow duplicate mixins within a stylesheet.
+  scss/no-duplicate-mixins: true
+
+  # Disallows the use of global function names, as these global functions are now located inside built-in Sass modules.
+  scss/no-global-function-names: true
+
   # Disallow linebreaks after Sass operators.
   scss/operator-no-newline-after: true
 
diff --git a/package.json b/package.json
index 7986b3a4..2fae36fe 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
     "url": "https://github.com/philwareham/textpattern-classic-admin-theme/issues"
   },
   "devDependencies": {
-    "autoprefixer": "9.7.4",
+    "autoprefixer": "9.8.0",
     "cssnano": "4.1.10",
     "grunt": "1.1.0",
     "grunt-cli": "1.3.2",
@@ -36,12 +36,12 @@
     "grunt-contrib-watch": "1.1.0",
     "grunt-postcss": "0.9.0",
     "grunt-sass": "3.1.0",
-    "grunt-stylelint": "0.14.0",
+    "grunt-stylelint": "0.15.0",
     "load-grunt-tasks": "5.1.0",
-    "sass": "1.26.2",
-    "stylelint": "13.2.0",
+    "sass": "1.26.5",
+    "stylelint": "13.5.0",
     "stylelint-order": "4.0.0",
-    "stylelint-scss": "3.14.2",
+    "stylelint-scss": "3.17.2",
     "uglify-save-license": "0.4.1"
   },
   "dependencies": {
@@ -51,7 +51,7 @@
     "scrollspy-js": "0.1.3"
   },
   "optionalDependencies": {
-    "fibers": "4.0.2"
+    "fibers": "5.0.0"
   },
   "browserslist": [
     "> 0.5%",
diff --git a/src/assets/sass/modules/_code-highlighting.scss b/src/assets/sass/modules/_code-highlighting.scss
index 63651518..fe5d02f9 100644
--- a/src/assets/sass/modules/_code-highlighting.scss
+++ b/src/assets/sass/modules/_code-highlighting.scss
@@ -63,7 +63,7 @@ pre[class*="language-"] {
 .token.url,
 .language-css .token.string,
 .style .token.string {
-    background: hsla(0, 0%, 100%, 0.5);
+    background: hsla(0deg, 0%, 100%, 0.5);
     color: #a67f59;
 }
 
diff --git a/src/assets/sass/modules/_links.scss b/src/assets/sass/modules/_links.scss
index fbb02a25..27fb754f 100755
--- a/src/assets/sass/modules/_links.scss
+++ b/src/assets/sass/modules/_links.scss
@@ -86,4 +86,4 @@ a {
 [dir="rtl"] .txp-skip-link {
     right: 1px;
     left: auto;
-}
\ No newline at end of file
+}