⚒️ Restructured Sass organisation (#83)

*  🌈  Organise colors with vars only

*  ➕ New file structure

* File restructuring

*  ⚒️ Fix build issue

* Rearranged files

assets/css/abstracts/_functions.scss

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