🐛 Bug: Find a truly transparent YouTube svg

[JoshuaKGoldberg]

Bug Report Checklist

• I have tried restarting my IDE and the issue persists.
• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Expected

In dark mode, the YouTube icon should have a transparent play button in the center... or failing that, a dark/black one. Not a white one.

Actual

Looking at http://localhost:4321/about#squiggle-tools, we can see a white play button in the center:

Additional Info

I haven't looked at all for a better svg. The current one in the repo is https://github.com/SquiggleTools/SquiggleConf/blob/5e27fe307cb1e58014b76800bc3b96e79c0c58b1/src/assets/youtube.svg.

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