Scroll Bar

Scroll bar, a slim vertical matte pill track 0.008 m wide, 0.003 m thick (length 0.16-0.6 m, ends never scale), with a pill thumb floating 0.002 m off it, glowing in the accent; position (0-1) places it, thumbSize (0.1-0.5) sizes it. Hover floats the thumb up.

风格：low-poly, flat-shaded vertex colors, no textures, 2 materials: the shared opaque one plus a distinct surface (glass, water or chrome), which stays its own mesh through mergeAssets rather than merging into the rest; shares palette and scale with its kit