A hero can compile successfully and still have the wrong line breaks, an illustration that dominates the copy, or spacing that looks nothing like the reference. The next edit needs evidence from the page the browser actually rendered.

Ant Ling's Ling-3.0-flash-VL frontend demo shows a generate → render → capture → compare → revise loop. One segment turns a London illustration with Big Ben, a Tube sign and a red bus into a landing page. Another shows a reference site and the local result side by side. There are visible layout differences, which makes the comparison stage more interesting than a claim of instant replication.

The useful input for that stage is a pair of images at a known viewport: the reference and the current render. Feedback can then name an observable mismatch and an intended change: the heading wraps a line too early; the image takes too much horizontal space; the next section starts too far down.

Keep that visual feedback attached to the relevant route and state. A screenshot of the initial page says little about the open menu or the narrow layout.

VL supplies the visual interpretation here. The surrounding environment still has to run the app, capture screenshots and expose logs or DOM information. Interaction, accessibility and viewport coverage need their own checks. What this demo adds is a concrete feedback source for the next CSS/layout revision.