v0.12.0 — sidebar, vertical tabs, custom toolbar

Three browser states a theme has probably never been tested in, captured on every run.

Sidebar — bookmarks and history

Two views now, with their trees expanded — a fresh profile shows them collapsed, so the old single view was mostly empty panel.

Vertical tabs

Firefox 133+ doesn't restyle the tab strip, it moves it: #tabbrowser-tabs leaves #TabsToolbar for #vertical-tabs. Every #TabsToolbar > … rule a theme owns silently stops matching, while unscoped .tabbrowser-tab rules keep applying horizontal geometry to a vertical column. Skipped automatically on builds without it.

Customised toolbar

The nav bar with widgets moved into it — by default the new tab button, the rearrangement many theme READMEs ask users to make by hand.

fxcss watch --toolbar "new-tab-button>nav-bar, -downloads-button"
fxcss shot  --toolbar "home-button>nav-bar@0" --out shots/

widget>area@position moves, -widget removes. Unknown widget ids are reported rather than silently rendering nothing.

Verified on 153.0.3: two full runs identical across all 18 views, and rules only these views can render change exactly those views and no others — now asserted in CI.

pipx upgrade fxcss