feat(isabelle-edits): Adds spacing, heading, and border utilities

Adds utility classes for spacing, headings, and borders to provide more flexible styling options.

This commit introduces:
- Spacing utilities with responsive adjustments for different screen sizes.
- A heading selector for simplified styling of heading elements.
- A border utility for applying a consistent border style.

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

@@ -1,3 +1,30 @@
+// Spacers
+$section-spacer: rem-calc(50px);
+$section-spacer-small: rem-calc(25px);
+
+.section-spacer {
+    margin-top: $section-spacer;
+    @include bs5-media-breakpoint-up(lg) {
+        margin-top: calc($section-spacer * 1.5);
+    }
+    &--small {
+        margin-top: $section-spacer-small;
+        @include bs5-media-breakpoint-up(lg) {
+            margin-top: calc($section-spacer-small * 1.5);
+        }
+    }
+}
+
 // Header selector for interpolation
 // Example usage: #{$headings} { ... }
 $headings: "h1, h2, h3, h4, h5, h6, .h1, .h2, .h3, .h4, .h5, .h6";
+
+// Background
+.bg__block {
+    // background: url(../img/bg.svg) repeat center center, $tertiary;
+}
+
+// Border
+.bordered {
+    border: 1px solid $border-color !important;
+}