Sites had to copy the entire stylesheet to change colors or sizing.
Every value is now backed by a --cookie-* custom property with the
original value as fallback, so sites can override just what they need
from their own CSS. Also fixes the README's @import path, which had
gone stale since the stylesheet was renamed and moved in 5597e11.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Silently returning made a missing banner.html integration
indistinguishable from a working page, which cost real debugging
time. Fail loud instead, pointing at the README.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
danielandClaude Sonnet 5