Plan step 36. <x-button> renders data-md-button with its variant, colour,
size, shape, icon-button width, selected state and compact FAB as
data-md-* attributes, and passes the glyph's size to <x-icon>.
button.css draws Button*Tokens' geometry per size, the colour roles
through custom properties that the disabled treatment replaces, the
state layer, focus ring and 48px target, and the compact FAB below
600px. Its corner rules carry no specificity (:where), so a group's
stylesheet reshapes the buttons inside it with any selector; the
split button no longer passes an empty corners prop, which is gone.
data-icon-button becomes data-md-icon-button, also in groups.css,
toolbar.css and theme-toggle's own button (navigation group), and the
AppBarTest assertions follow the new hooks.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9
