Remove max-width constraints from LMArena chat containers for a full-width reading experience. Works across all chat modes.
Expand your chat view to full width on LMArena for a better reading experience.
max-width constraints from chat containersLMArena's default chat layout restricts message width, which can be frustrating when:
This script removes those width constraints, allowing chat messages to use your full screen width.
Install a userscript manager:
Click the Install button on this page
Visit LMArena and enjoy full-width chat!
This script uses a multi-layered approach to ensure comprehensive coverage:
| Layer | Method | Purpose |
|---|---|---|
| 1 | CSS injection at document-start |
Immediate effect, prevents flash of styled content |
| 2 | Multiple CSS selectors | Covers Sentry components, Tailwind classes, structural elements |
| 3 | JavaScript DOM traversal | Handles edge cases like inline styles |
| 4 | MutationObserver | Responds to dynamically loaded chat messages |
[data-sentry-component="UserMessage"][data-sentry-component="BotMessage"][data-sentry-component="AIMessage"][data-sentry-component="ParallelMessageGroup"]max-w-* utility classesmain ol)| Browser | Status |
|---|---|
| Chrome / Edge / Brave | ✅ Fully supported |
| Firefox | ✅ Fully supported |
| Safari | ✅ Supported (requires userscript extension) |
Note: This script uses CSS :has() selector, which is supported in all modern browsers (Chrome 105+, Firefox 121+, Safari 15.4+).
Q: Does this affect Arena Battle mode's side-by-side layout? A: The script removes width constraints but preserves the flex layout structure. Both Model A and Model B panels will expand within their respective containers.
Q: Will this break if LMArena updates their site?
A: The script uses stable data-sentry-component attributes which are less likely to change. If issues occur, please report them!
Q: Can I customize which pages this applies to?
A: You can modify the @match patterns in the script header to limit the scope.
If you encounter any issues or have suggestions, please:
MIT License — Feel free to modify and redistribute.