Fix Non-English Anchor Popover Positioning Issue and Update Type Hint

[cmj2002]

This PR addresses two issues:

1. Corrects the non-English anchor popover positioning problem by changing the hash passed to querySelector to decodeURIComponent(hash). This ensures that the popover correctly scroll its content to the corresponding title for non-English anchors. (fix #409)
2. Updates the type hint of mouseEnterHandler from HTMLLinkElement to HTMLAnchorElement as the passed element is an <a> element, not a <link> element. Reference: MDN Documentation.