Using header tags for font size

Using header tags for font size

"Make that line an H3 so it looks bigger."

Stop.

Headings are a document outline, not a type scale. The mistake — picking H2/H3/H4 by how big it renders — produces pages where the visual hierarchy and the semantic hierarchy disagree completely. A bold callout becomes an H3; a real subsection stays a styled <p>.

Here's what actually happens: a parser building the page outline (and AI systems increasingly do exactly this to extract structure) reads a topical tree that doesn't match what the content is about. Your '5 key benefits' subsection is invisible as a section because you styled it instead of structuring it. The bigger-looking decorative line gets treated as a major topic boundary.

Fix: choose heading level by logical depth, then style it with CSS to look however you want. font-size and <h2> are unrelated decisions. A heading earns its level by what it contains, not by how loud it looks.