Revert "chore: migrate deprecated sass functions"

This reverts commit c9ea877.

_sass/minima.scss

@@ -1,5 +1,4 @@
 @charset "utf-8";
-@use "sass:color";
 
 // Define defaults for each variable.
 
@@ -16,8 +15,8 @@ $background-color: #fdfdfd !default;
 $brand-color:      #2a7ae2 !default;
 
 $grey-color:       #828282 !default;
-$grey-color-light: color.adjust($grey-color, $lightness: 40%) !default;
-$grey-color-dark:  color.adjust($grey-color, $lightness: -25%) !default;
+$grey-color-light: lighten($grey-color, 40%) !default;
+$grey-color-dark:  darken($grey-color, 25%) !default;
 
 $table-text-align: left !default;
 

_sass/minima/_base.scss

@@ -1,5 +1,3 @@
-@use "sass:color";
-
 /**
  * Reset some basic elements
  */
@@ -109,7 +107,7 @@ a {
   text-decoration: none;
 
   &:visited {
-    color: color.adjust($brand-color, $lightness: -15%);
+    color: darken($brand-color, 15%);
   }
 
   &:hover {
@@ -234,21 +232,21 @@ table {
   margin-bottom: $spacing-unit;
   width: 100%;
   text-align: $table-text-align;
-  color: color.adjust($text-color, $lightness: 18%);
+  color: lighten($text-color, 18%);
   border-collapse: collapse;
   border: 1px solid $grey-color-light;
   tr {
     &:nth-child(even) {
-      background-color: color.adjust($grey-color-light, $lightness: 6%);
+      background-color: lighten($grey-color-light, 6%);
     }
   }
   th, td {
     padding: ($spacing-unit * 0.3333333333) ($spacing-unit * 0.5);
   }
   th {
-    background-color: color.adjust($grey-color-light, $lightness: 3%);
-    border: 1px solid color.adjust($grey-color-light, $lightness: -4%);
-    border-bottom-color: color.adjust($grey-color-light, $lightness: -12%);
+    background-color: lighten($grey-color-light, 3%);
+    border: 1px solid darken($grey-color-light, 4%);
+    border-bottom-color: darken($grey-color-light, 12%);
   }
   td {
     border: 1px solid $grey-color-light;