A renderer performance trace showed the minimap strips as a standing
source of main-thread frame work: each strip transitioned
background-color (paint) and width (layout), and both fire constantly —
scrolling or streaming flips a band of in-view states at once, and the
hover fisheye animates several widths at a time — so any interaction
kept a 60fps style/layout/paint pipeline running.

The strip now animates only compositor-friendly properties: width tiers
are scale-x on a fixed-width box, and the in-view highlight is a bright
overlay faded with opacity. The scroll handler also skips no-op
data-in-view attribute writes, which previously re-dirtied style state
for every strip on every scroll tick.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>