[connorjclark]

Summary

Node colors could get dark and saturated deep in the tree (e.g. when zoomed into a bundle's node_modules), making captions hard to read. Contrast of the #474747 caption text dropped as low as ~1.2:1 for blue/purple hues.

• Colors use OKLCH instead of HSL so every hue has the same perceived lightness. Lightness/chroma still vary with depth, but are clamped (L ≥ 0.86, C ≤ 0.06) so captions stay ≥ 5.9:1 for every hue.
• Depth is relative to the node currently in view, so zooming in brings back the lighter colors.
• All mode gets a faint border so same-colored siblings are distinguishable.
• Duplicate highlight colors also use OKLCH.

Related Issues/PRs

Part of #16400