* { box-sizing: border-box; } /* 🔴 THE TAB STRIP JITTERS WITHOUT THIS. Seth, 2026-08-23: "the tabs kind of jitter around a little bit whenever you jump between them." Nothing about the tabs moves. What moves is the VIEWPORT. Every tab is a different page of a different height, so switching to a short one (Account) retracts the page scrollbar and switching to a tall one (Why This App Exists) puts it back — and a scrollbar is ~15px of width taken off the right of the layout viewport. `.topbar` centres the strip in the middle cell of a `1fr auto 1fr` grid (styles/layout.css), so the strip's centre is the viewport's centre: it slid ~7px sideways on every switch that changed the page's height, and slid back on the way out. `scrollbar-gutter: stable` reserves the gutter whether or not a scrollbar is in it, so the layout viewport is one width for every page. It belongs on the scrolling element — , not . Anything else centred on the viewport (the practice notch, modals) stops moving with it. Not `overflow-y: scroll`, which reserves the gutter by drawing a dead scrollbar on pages that do not scroll. */ html { scrollbar-gutter: stable; } body { margin: 0; font-family: var(--ui-font); color: var(--text); background: var(--bg); min-height: 100vh; }