feat(isabelle-edits): Clarify theme structure and add SVG icon support

Improves theme organization by adopting a 7-in-1 SCSS structure.

Introduces support for SVG icons within templates, enhancing visual flexibility.

Adds a checkmark SVG asset.

falcon/_dev/css/theme/custom/_custom.scss

@@ -1,13 +1,19 @@
-// NOTE: All bootstrap overrides have been configured under themes/falcon/_dev/css/abstracts/variables/bootstrap
+/* 
+This is the main custom SCSS file for the Falcon theme. 
+
+I am loosely following the 7 in 1 structure for better organization of the styles. Learn more here:
+https://medium.com/@diyorbekjuraev77/be-a-master-at-creating-the-7-1-sass-pattern-776fdfb5a3b1
+
+⚠️NOTE: All bootstrap overrides have been configured under themes/falcon/_dev/css/abstracts/variables/bootstrap
+*/
 
 //Abstracts: Things used throughout the site such as utility classes and generic overrides.
+@import "abstracts/utilities";
 //@import "abstracts/base";
 @import "abstracts/functions";
 @import "abstracts/mixins";
-//@import "abstracts/utilities";
 
 // Components: parts of the theme itself that are not associated with a module.
-//@import "components/";
 @import "components/forms";
 
 // Modules: Styling for specific modules.

falcon/_dev/css/theme/custom/abstracts/_utilities.scss

@@ -1,3 +1,7 @@
+// Header selector for interpolation
+// Example usage: #{$headings} { ... }
+$headings: "h1, h2, h3, h4, h5, h6, .h1, .h2, .h3, .h4, .h5, .h6";
+
 // Color utility classes
 @each $name, $color in $theme-colors {
     .bg-#{$name} {