_sass: Simplify and inline variables

_sass/custom/custom.scss

 // Just the Class dependencies
-@import 'variables';
 @import 'mixins';
 @import 'card';
 

_sass/custom/mixins.scss

 @mixin abstract-card() {
-  box-shadow: $box-shadow;
+  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.07), 0 4px 14px rgba(0, 0, 0, 0.05);
   margin-left: -$gutter-spacing-sm;
   margin-right: -$gutter-spacing-sm;
   margin-bottom: $sp-4;

_sass/custom/staffer.scss

@@ -12,7 +12,7 @@
 
 .staffer-image {
   border-radius: 50%;
-  height: $staffer-image-size;
+  height: 100px;
   margin-right: $sp-4;
 }
 

_sass/custom/variables.scss

-// Typography
-$body-font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
-
-// Layout
-$gutter-spacing: $sp-6;
-$gutter-spacing-sm: $sp-4;
-$nav-width: 216px;
-$nav-width-md: 216px;
-$content-width: 784px;
-
-// Components
-$box-shadow: 0 1px 3px rgba(0, 0, 0, 0.07), 0 4px 14px rgba(0, 0, 0, 0.05);
-$module-date-color: $link-color;
-$staffer-image-size: 100px;