docs: make nav tabs sticky for easier navigation while scrolling

Author: MeAkib

docs/src/app/pages/component-viewer/component-viewer.scss

@@ -30,6 +30,10 @@ app-component-viewer {
 
 .docs-component-viewer-tabbed-content {
   margin-bottom: 25px;
+  position: sticky !important;
+  top: 0;
+  z-index: 1;
+  background: var(--mat-sys-surface);
 }
 
 .docs-component-viewer-content {
@@ -49,7 +53,7 @@ app-component-viewer {
   }
 
   table-of-contents {
-    top: 35px;
+    top: 50px;
     position: sticky;
 
     // Reposition on top of content on small screens and remove