[lexical-playground] Bug Fix: Convert remaining icon glyphs to mask-image for forced-colors support

[mayrang]

Description

PR #8591 converted toolbar icon glyphs from background-image to mask-image for forced-colors accessibility support. Three i.xxx selectors were missed and still rendered as solid rectangles in forced-colors mode:

• i.star — Review icon in the slash menu
• i.bucket — color button in the sticky note component

Also removes the dead i.palette CSS rule and its unused palette.svg asset (no references in any tsx/ts file).

Additionally, per @levensta's suggestion, increased toolbar padding from 4px to 6px and added scrollbar-width: thin so buttons aren't as crowded and the scrollbar is less visually intrusive.

Test plan

• Manual playground: slash menu → Review icon renders correctly (was a black square)
• Manual playground: insert Sticky Note → color button icon renders correctly
• Verified no remaining i.xxx selectors use background-image (awk scan, zero hits)
• Manual playground: toolbar padding/scrollbar visually improved, height matches compact state
• prettier clean

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
lexical	Ready	Preview	Jul 3, 2026 11:46pm
lexical-playground	Ready	Preview	Jul 3, 2026 11:46pm

[levensta]

Let's also slightly reduce the size of the toolbar scrollbar using the scrollbar-width: thin; property. It would also be a good idea to increase the padding from 4 to 6px so that the buttons aren't too crowded

After these cosmetic manipulations, the height of the toolbar will be the same as in the compact state

[mayrang]

Agreed — the version with your suggestions looks visually better. Applied padding: 6px and scrollbar-width: thin to the toolbar.