How much of the global CSS does the homepage use?
The mobile PageSpeed score is held down by JavaScript.
- Kind
- Benchmark
- State
- Done
- Run on
- 2026-08-04
Why I ran it
To decide whether to spend the next performance pass on JS or CSS.
Setup & method
Selector coverage over the live homepage DOM, then every cut selector checked against the rendered HTML of all 40 sitemap routes.
What happened
Only 26.4 KB of 304 KB of rules matched the homepage. Most of the rest styled three superseded homepage designs. Static analysis flagged five classes as dead that were really built at runtime, like case-${archetype}.
Result (one line)
8.7% of the CSS was used. Pruning removed 116 KB of source; the built bundle went from 51 KB to 35 KB gzipped on every route.
What surprised me
It was CSS, not JS. And grep alone would have deleted five live classes.
Limits — what this does not prove
Coverage was measured on rendered pages; states that only appear after interaction were protected by hand, not measured.