Tier 4 visual fidelity, audit 4.5 (t4 line 235): the border and the label/icon now use the prototype's two DIFFERENT opacities (rgba(255,255,255,.16) stroke vs rgba(242,247,250,.6) text/icon, previously one shared 50% colour for both), padding is a uniform 14 instead of symmetric(18,16), and the icon is a plain add glyph at 20px instead of add_circle_outline_rounded.