The undo and redo arrows read as arrows now, and the run buttons sit on the middle of the window: the first pair was a three-quarter circle with a triangle at the end of the arc, which at 16 units puts the head exactly where the arc already is - the two melt into one another and the icon reads as a comma, which is what the screenshot showed - so both are drawn as a flat head standing free beside its tail, a triangle pointing left with a tail curving away to the right and down (redo mirrored), and they were checked in the real build, not only in an SVG renderer, because ImageMagick draws these paths a good deal more kindly than Pixi does; the play/pause pair was off centre because the row has three flexible children - the two spacers around it and the notice label, which is flexible since #177 so that the bar does not overflow at 1280 px - and each takes a third of what is left, so Toolbar.layout() now moves the pair onto the middle of the bar after super.layout(), clamped between the redo edge and the start of the notice so that a narrow window pushes the pair back instead of laying two captions on top of each other; one new e2e check in 46a measures that middle against innerWidth/2 (1148 checks), and the README gained the screenshot of the editor

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

tools/e2e/46-topbar.mjs

@@ -34,6 +34,17 @@ export async function topbar(t) {
       buttons.pauseEnabled === false,
     JSON.stringify(buttons),
   );
+  // The pair is centred on the bar itself. The row cannot do that on its own: the spacers around
+  // the two buttons share the free space with the flexible notice and so get a third of it each,
+  // which used to leave the pair well left of the middle.
+  const play = await json('__gm.toolbarAt("play")');
+  const pause = await json('__gm.toolbarAt("pause")');
+  const barCentre = await json('window.innerWidth / 2');
+  check(
+    'play and pause sit on the middle of the bar, not on the middle of what is left over',
+    Math.abs((play.x + pause.x) / 2 - barCentre) <= 2,
+    JSON.stringify({ middle: (play.x + pause.x) / 2, barCentre }),
+  );
   await shot('46-topbar');
 
   // 46b. The one menu. Four entries, and the separator between what opens a project and what