Make the UI more performant by not reflowing

Fixes the height of the component until it’s loaded so that it doesn’t
causes the page to reflow while it’s rendering the buttons.

Stops the options being shown and then immediately hiding on initial
page load.

app/assets/stylesheets/components/radio-select.scss

@@ -23,6 +23,17 @@
 
   .js-enabled & {
 
+    height: 60px;
+    overflow: visible;
+
+    .block-label {
+      display: none;
+    }
+
+    .js-block-label {
+      display: inline-block;
+    }
+
   }
 
 }