The heads of the Song tab had four rough spots. Panned down, the first track had no line above it. The M and S letters sat high in their buttons. A volume or pan slider could only be dragged back to the middle by eye. Muting a track paled its volume slider. - The first track draws a border along its top, in the lanes and in its head, like the one below every track. - M and S sit in the middle of their buttons. A label of the heads can now carry a height and is centred in its box. - A double-click on a head's volume or pan sets it back to 0: the volume to 0 dB, the pan to the middle. It is one undo step of its own after the step the first click set. - Mute only lights its own button. The volume slider keeps its colour, so a muted head no longer looks out of step. Tests: - e2e 65 on melektaus-atx: ALL PASSED, 27 checks (+1) - typecheck, ESLint, Prettier: clean (also after the mute change) - screenshot on stein2: border above track 1, M and S with 4 px free above and below the letter in a 16 px button Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>