Unblocking CSS/JS in robots.txt: mobile-usable pages +52pts

Unblocking CSS/JS in robots.txt: mobile-usable pages +52pts

Legacy site disallowed /assets/. Render audit on a 500-URL sample showed Googlebot rendering pages naked.

Pages rendering with full layout ▓▓▓░░░░░░░ 31%
Rendering broken/unstyled ▓▓▓▓▓▓▓░░░ 69%

Google couldn't fetch the stylesheets to judge layout or mobile-friendliness.

We removed the disallow on /assets/css/ and /assets/js/.

Delta after 4 weeks:
— Pages rendering complete: 31% → 89%
— 'Mobile usable' in inspection sample: 34% → 86% (↑52pts)
— Median position (mobile): 19.1 → 15.3 (↓3.8)

So what: blocking render assets doesn't save crawl budget — it blinds the renderer. The single-line robots.txt edit was the highest-ROI change in the whole audit.