Constant GLASS_EDGE_HOVER_ALPHA 

pub const GLASS_EDGE_HOVER_ALPHA: u8 = 28; // 28u8

Edge alpha of a hovered selector. Below HAIRLINE_ALPHA — a hover is pointed at, not chosen, and a full hairline reads as a second active tab. Carries more of the state than it looks like: the light preset’s translucent body only lands ~3 levels off its ground (bar sits ~19 below white) versus ~12 on a graphite ground, but Colors::hairline_on picks whichever polarity moves the ground it’s actually drawn on.