Hover any element below to see the preview ring. Click to commit selection and open the floating toolbar. Use the toolbar to Move / Resize / Style / Duplicate / Delete / Inspect / Info. Esc or outside-click dismisses. Mobile: long-press the element to commit. Alt+Click walks one ancestor up.
Pick anything in this box. The toolbar reads from spec §3 and the mutation log feeds diff-format.js.
This is a draggable / styleable card. Try Move, Style → color.
Second card. Try Duplicate, Delete (3s undo ghost).