Optimize the highlighting logic for child elements inside <li>

[Tenormis]

Final rules summary:

• Must be inside the main content root (.VPDoc main .vp-doc > div)
• Direct parent must be one of the allowed container tags (['DIV', 'BLOCKQUOTE', 'DETAILS', 'FIGURE', 'UL', 'OL', 'LI', 'TABLE', 'THEAD', 'TBODY'])
• DIVs containing a direct <pre> child (code blocks) are excluded
• When the parent is <li>, the current node must itself be a container tag or <p>