[U] Migrate sass

src/css/global.sass

@@ -1,5 +1,5 @@
-@import colors
-@import font
+@use "colors"
+@use "font"
 
 // Google Fonts
 // TODO: Localize
@@ -119,7 +119,7 @@ body
   -webkit-font-smoothing: antialiased
   -moz-osx-font-smoothing: grayscale
   text-align: center
-  color: $color-text-main
+  color: colors.$color-text-main
 
   // Max width and center
   max-width: 900px
@@ -170,11 +170,11 @@ html
   text-justify: inter-word
 
   a
-    color: $color-text-special
+    color: colors.$color-text-special
     text-decoration: none
 
   h1, h2
-    border-bottom: 1px solid $color-text-special
+    border-bottom: 1px solid colors.$color-text-special
     font-size: 1.5em
     margin-top: 1em
 
@@ -218,4 +218,4 @@ html
     align-items: center
 
     font-size: 0.8em
-    color: $color-text-light
+    color: colors.$color-text-light

src/css/responsive.sass

@@ -1,4 +1,4 @@
-@import "../css/colors"
+@use "../css/colors"
 
 $width: 600px
 
@@ -14,7 +14,7 @@ $width: 600px
     margin-bottom: 0
 
   .subtitle
-    color: $color-text-light
+    color: colors.$color-text-light
 
 
 // Phone layout