The React port replaced CSS class names with Tailwind utilities, breaking three visual contracts: - SessionCard used inline bg-* classes instead of .is-active/.is-open/ .is-previewing that the styles.css cascade targets. - PaneTitle used className "at-title" instead of "attach-title", so font, overflow, and child layout rules never applied. - MultiView's Pane never applied .is-focused or .is-preview, so every pane matched :not(.is-focused) and was dimmed to 0.45 opacity. Closes #256 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>