Style fixes for tools & 404 page:

- Set Bootstrap colors for background colors
- Adjust button padding to work in more contexts
- Removed unused tool CSS. Migrated some styles to SCSS.
- Fix sticky overlap in faucets sidebar
- Make 404 page inherit from base template

styles/_top-nav.scss

@@ -47,7 +47,7 @@
     .btn-outline-secondary {
       font-size: 14px;
       line-height: 125%;
-      margin-top: .5rem;
+      margin-top: 1rem;
     }
     @include media-breakpoint-down(md) {
       .wrap-button {