Updating to normalize.css 8.0.1 minus IE fixes. Other sass file cleanup as well.

assets/sass/base/document/_document.scss

@@ -16,8 +16,18 @@ html {
   // On short pages, we want any background gradients to fill the entire height
   // of the browser.
   min-height: 100%;
+  // Use the saner border-box model.
+  box-sizing: border-box;
 
   @include respond-to(xxl) {
     @include define-type-sizing($base-font-size-2, $base-line-height-2);
   }
 }
+
+// Use the saner border-box model for all elements.
+*,
+*::before,
+*::after {
+  box-sizing: inherit;
+}
+