move more junk out of index.css and into components

components/Heading/Heading.tsx

@@ -16,7 +16,7 @@ const Heading = ({ as: Component, id, className, children, ...rest }: Props) =>
 
       {/* add anchor link to H2s and H3s. ID is already generated by rehype-slug. `#` character inserted via CSS. */}
       {id && (Component === "h2" || Component === "h3") && (
-        <a className={styles.anchor} href={`#${id}`} tabIndex={-1} aria-hidden="true" />
+        <a className={classNames("no-underline", styles.anchor)} href={`#${id}`} tabIndex={-1} aria-hidden="true" />
       )}
     </Component>
   );