@Jdrewniak's POC patchdemo: https://patchdemo.wmflabs.org/wikis/f26aec5ef8/wiki/Ulm?useskin=vector-2022

and the accompanying patch https://gerrit.wikimedia.org/r/c/mediawiki/skins/Vector/+/814840

This bolds the font and stretches the width of the active element to 100% of the TOC width + TOC padding, (i.e. to the very edge of the sidebar container).

That should prevent text-wrapping due to bolding as best a possible, but on some OS's or browsers, it might result in the text of the active element overlapping the scrollbar (only when the scrollbar is visible of course). I'd consider that a minor edge-case though.

{F35419362}

Change 814840 had a related patch set uploaded (by Jdrewniak; author: Jdrewniak):

[mediawiki/skins/Vector@master] TOC with bold text.

https://gerrit.wikimedia.org/r/814840

@Jdrewniak, @bwang - did a quick check on this, and I'm seeing the following:

When I go to the "dog" article, the hearing section is immediately bolded without my scrolling to it (https://en.wikipedia.beta.wmflabs.org/wiki/Dog)

When I go to the "domestication" article the bolding doesn't appear (https://en.wikipedia.beta.wmflabs.org/wiki/Domestication)

@olga sorry the patch hadn't been merged when you tested that (CI issue). It should be merged shorty though.
You did discover an interesting edge case though! Wikitext heading can contain HTML, and the "Hearing" heading actually contains a <b> (bold) tag.

We could attempt to override that specific style with font-weight:normal but maybe there is a use-case for intentionally adding the <b> tag? not sure.

Change 814840 merged by jenkins-bot:

[mediawiki/skins/Vector@master] TOC with bold text.

https://gerrit.wikimedia.org/r/814840

The patch is live on beta now. Looking at the Dog article, you can see that the "Hearing" heading is still bold, but the active section is still distinguished by being colored black and bold.

Looks good now! Thanks @Jdrewniak

In T314670#8207438, @Edtadros wrote:

@alexhollender_WMF , I think I need more clarification as to what the line wrapping behavior should be.

@Edtadros when the active section link gets bolded it gets wider. In the past this was leading to certain section links wrapping onto a new line when they were active/bolded. Jan added some special padding to protect against this wrapping in most cases. Below is a screen recording that shows what we don't want...the "Other relationship with humans" section link wraps onto a new line when it's active/bolded: