The previous fix (e3556bd) added `flex: 1 1 0` to `.st-tool-arg` in
`structured.css`, but `styles.css` has a duplicate copy of the same
rules that was left stale. Because both load, the unfixed copy in
`styles.css` can override the fix and re-enable horizontal scroll.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>