fix: Improve accuracy of toc highlighting (#436)

Resolves #414

The `.o-container` position has been changed to relative and there is no
need to remove the scroll padding.

Co-authored-by: Robert Schuster <77234379+therobrob@users.noreply.github.com>

Author: MoritzWeber0

assets/js/highlightHeadline.js

@@ -27,8 +27,7 @@ function initHighlightHeadline() {
     for (let i = 0; i < headings.length; i++) {
       const heading = headings[i];
 
-      // Add the scroll-padding-top defined in styles.scss + 1px to trigger the detection
-      if (heading.offsetTop <= window.pageYOffset + 81) {
+      if (heading.offsetTop <= window.pageYOffset) {
         currentHeading = heading;
       } else {
         break;