Move literal width into units

src/components/language-selector/language-selector.css

@@ -8,8 +8,8 @@
 /* Position the language select over the language icon, and make it transparent */
 .language-select {
     position: absolute;
-    width: 3rem;
-    height: 3rem;
+    width: $language-selector-width;
+    height: $menu-bar-height;
     opacity: 0;
     user-select: none;
     font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;

src/components/menu-bar/menu-bar.css

@@ -54,7 +54,7 @@
 
 .language-menu {
     display: inline-flex;
-    width: 3rem;
+    width: $language-selector-width;
 }
 
 .menu {

src/css/units.css

@@ -6,6 +6,7 @@ $space: 0.5rem;
 $sprites-per-row: 5;
 
 $menu-bar-height: 3rem;
+$language-selector-width: 3rem;
 $sprite-info-height: 6rem;
 $stage-menu-height: 2.75rem;