Small fixes

- @mixin and @include for dark scheme
- unset `--font-weight` in `hgroup`

scss/content/_typography.scss

@@ -195,9 +195,9 @@ hgroup {
 
   > *:last-child {
     --color: var(--muted-color);
+    --font-weight: unset;
     font-family: unset;
     font-size: 1rem;
-    font-weight: unset;
   }
 }
 

scss/themes/default.scss

@@ -15,12 +15,15 @@
 
 // Dark theme (Auto)
 // Automatically enabled if user has Dark mode enabled
+@import "default/dark";
 @media only screen and (prefers-color-scheme: dark) {
-  @import "default/dark";
+  :root:not([data-theme="light"]) {
+    @include dark;
+  }
 }
 
 // Dark theme (Forced)
 // Enabled if forced with data-theme="dark"
 [data-theme="dark"] {
-  @import "default/dark";
+  @include dark;
 }

scss/themes/default/_dark.scss

@@ -1,6 +1,7 @@
 // Default: Dark theme
-:root:not([data-theme="light"]) {
 
+@mixin dark {
+  
   // Document
   color-scheme: dark;
   --background-color: #{mix($black, $grey-900, 37.5%)};