Explore
Run the panel on an ordinary page. Start with root-cause groups and inspect precise elements.
Rendered UI evidence
Runtime layout checks for rendered UIs.
OverflowLint turns live DOM geometry and browser hit testing into structured, actionable findings for developers, Playwright, and coding agents.
{ "rule": "interactive-covered", "rule_level": "essential",
"severity": "error", "confidence": "high", "selector":
"button.sync", "diagnosis": { "causes": ["pointer-interception"],
"suggestions": ["adjust-stacking"] } }
Explore the failure. Develop against evidence. Verify the same rendered state.
Develop
Use rule IDs, selectors, rectangles, typed evidence, likely causes, and preview-ready fix candidates to make a targeted fix.
Verify
Inject the panel-free core in Playwright and enforce policy across Chromium, Firefox, and WebKit.
Useful before you annotate anything.
Document overflow, masked clipping, truncated text, covered native controls, flex/grid escapes, content overlap, and unusable interactive targets come from generic browser signals. Broad new heuristics are clearly labeled experimental. Optional contracts express product intent only where geometry cannot.
Render → scan → fix → rerun.
Ordinary scans distinguish observed and masked failures. Explicit text stress safely probes expanded, unbroken, URL, numeric, emoji, CJK, and mixed-script copy, then restores the page.
Know what it cannot prove.
A clean scan does not prove that a design looks good. OverflowLint does not replace visual review, accessibility testing, product judgment, or representative cross-browser coverage. It does not traverse iframes or closed shadow roots.
Stable distribution stays release-bound.
Install from npm, use the stable userscript, or drag the stable bookmarklet. Stable browser artifacts follow npm latest through jsDelivr; the website can describe unreleased main-branch behavior.
Dev bookmarklet & userscript
Tracks latest main on every push (0.5.0-dev.1787058512+b3d2ef5). Separate install from stable — may break.