⚒️ Restructured Sass organisation (#83)

*  🌈  Organise colors with vars only

*  ➕ New file structure

* File restructuring

*  ⚒️ Fix build issue

* Rearranged files

assets/css/_sass/_functions.scss

@@ -1,11 +0,0 @@
-@function pxToRem($pixels, $context: $browser-context) {
-  @if (unitless($pixels)) {
-    $pixels: $pixels * 1px;
-  }
-
-  @if (unitless($context)) {
-    $context: $context * 1px;
-  }
-
-  @return $pixels / $context * 1rem;
-}