demo · v140

Breakage Finder

Paste your HTML or CSS — this analyser flags every <h1> that lives inside <article> / <aside> / <nav> / <section> and every author rule that depends on the now-removed UA cascade. Use it to triage codebases before the rule disappears.

Paste HTML below. Each suspect h1 is shown with its ancestry chain.

recommended fix

For each h1 nested inside a sectioning element, demote to the explicit level that matches the visual hierarchy: h2 at depth 1, h3 at depth 2, and so on. Screen readers have always read the explicit level — they never used the implicit outline. The visual change is real but the accessibility tree is unaffected because the outline algorithm was never implemented.

see also