Docs
Read before you trust a number.
Short pages, written the way the app behaves today. Where the app can't do something, the docs say so.
Getting started
Install the app, open a page, open the inspector, pick an element and read its styles.
ReadPanels reference
What each panel shows today, and what it does not: Elements, Styles, Console, Network, Sources, Storage, Responsive, Info, Accessibility and Resources.
ReadWebKit limits and data sources
Why some values show a dash, where each value comes from, and how confidence is labelled.
Read