Limits
What a check of the page source can and cannot see, and how the report says so.
The audit reads the markup the server sends. That is enough for most structural rules and not enough for everything.
| Needs | Examples | Result |
|---|---|---|
| The markup | missing alt text, unnamed links and buttons, form labels, landmarks, ARIA | checked |
| Stylesheet text | removed focus outline, reduced motion, justified text | checked |
| Computed styles | colour contrast | checked from the stylesheets; undetermined over photos, behind absolutely positioned boxes, under filters or opacity |
| A moving focus | focus visibility | not run |
| Geometry | target size, overlap, reflow | not run |
| Scripts and interaction | content built by JavaScript, focus handling, dialogs | not seen |
How styles are computed
The tool resolves the cascade itself: specificity, cascade layers, !important, the style
attribute, inheritance, var() and @media for a 1280 px light window. A selector or media
condition it does not understand (:has(), container queries) makes the affected values
undetermined unless a certain rule wins anyway. Gradients are checked against their colour stops,
not every pixel. It has not been compared with a browser on a larger corpus.
Not run is not passed
A rule whose input is missing appears in the report as not run, with the reason. The summary counts them, so a clean result never hides a check that did not happen.
Pages built by scripts
The source of a single-page application holds little content, so the result says little about what a visitor sees. Use a browser-based tool such as auditmysite or axe there.