Tidy/simplify popup

[AlecRust]

Current Problem

Looks like lots of tweaks have happened to the popup, but there's various alignment issues, invalid HTML such as missing alt attribute, use of old align attribute etc.

Proposed Solution

Somewhat tidy up the popup HTML and CSS. Improves alignment/padding, reduces unnecessary flexbox usage, ~fixes "Your Work" not having equal columns~ etc.

Screenshots

Before	After

• [x] I agree to license my contribution under LGPL-3.0 or my contribution is from another project with a license compatible with LGPL-3.0

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[ajayyy]

The "Your Work" thing was on purpose since usernames can be long

[AlecRust]

OK, I've reverted the 50/50 columns and improved the width when editing username.

Before/after screenshots have been updated.