style: remove deprecated functions

src/styles/variables.scss

@@ -21,7 +21,7 @@ $z-index-back-to-top: $z-index-modal + 1;
 $bg-blur-radius: 4px;
 
 $color-white: #fff;
-$color-white-rgb: #{red($color-white)}, #{green($color-white)}, #{blue($color-white)};
+$color-white-rgb: 255, 255, 255;
 $color-black: #000;
 $color-primary: #1161fe;
 $color-primary-hover: #0e52d8;