CSS Overview on a phone
You can’t run Chrome’s CSS Overview on a phone, because it lives inside DevTools — and no mobile browser has DevTools. This does the same job from a URL bar, on any device.
Why the built-in tool is desktop-only
CSS Overview is a panel in Chrome DevTools. On a laptop you open it from More tools → CSS Overview and it reports a page’s colors, fonts, contrast issues and unused rules. But DevTools is a desktop feature. Mobile Chrome and mobile Safari have no developer tools at all, so there is no menu to open it from on the device in your hand.
“Just use remote debugging”
The usual answer is to plug an Android phone into a computer over USB and drive its Chrome from the desktop DevTools. That works, but it is not really running the tool on your phone — it is running it on a computer that happens to be looking at your phone. It needs the cable, a developer-mode toggle and a desktop in the first place. On an iPhone or iPad there is no equivalent for Chrome at all. If you are on a phone and want an answer, none of that helps.
What to do instead
Paste the URL into the box on the home page and the render happens on our server. The report comes back in whatever browser you already have open — the same fonts, colors, contrast and design tokens you would get on a desktop, laid out for a small screen. The finished report has its own link, so you can send it from your phone to a teammate or back to yourself for later.
It is the same inventory either way: see what it reports, or read how it works.