The rule that hides the list column while a workspace is open matched
the workspace panel's style attribute inside :has(). Chrome then treats
every inline-style write on the page as a possible change and restyles
the whole page, so extensions that move their buttons every frame took
a large workflow's canvas down to 2-3 fps. The container now gets an
anomalous-workspace-open class from a MutationObserver on the panel's
style (every module opening a workspace sets its display), and the CSS
keys off that class.
Found, measured and fix proposed by Lindemellis in issue #22.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>