How to visually edit an AI-generated app

Choose the editing approach for the change

Visual editing is useful when you can point to the problem more easily than describe the implementation. An oversized heading, a crowded form and an uneven grid are all good starting points. Start with the smallest change that would improve the screen, rather than asking for a complete redesign.

Browser developer tools let you inspect rendered elements and experiment with CSS immediately. Those experiments usually disappear when you reload. A focused AI request can turn a clear observation into a source change, but you still need to inspect the result. A source-aware visual editor aims to connect direct manipulation to project files; check its actual framework support and what it writes before relying on it.

These approaches can be combined. Use the browser to identify the element, express the intended outcome precisely, then review the saved code. A tool that edits a screenshot or a static mockup does not necessarily update your running app.

Worked example: give a signup form room to breathe

Suppose a form touches the edge of a wide screen and its input stretches too far to read comfortably. Give its container a maximum width, preserve a small gutter on narrow screens, and define a consistent gap between controls. The following original example uses ordinary CSS; it does not depend on Mello.

Here the maximum width is a design decision for a compact form, not a universal rule. Try the change with your actual labels and validation messages. If your application already has layout tokens, use those instead of introducing a parallel spacing system.

.signup {
  width: min(100% - 2rem, 32rem);
  margin-inline: auto;
  display: grid;
  gap: 1rem;
}
.signup input, .signup button {
  box-sizing: border-box;
  width: 100%;
  min-width: 0;
  min-height: 2.75rem;
}

Make the change durable

Locate the component that owns the form and its stylesheet or utility classes. Save the experiment there, then reload the page. If the change disappears, you have only edited the browser view. If unrelated forms change, the selector may be too broad.

Review the diff for changes to behavior. A spacing adjustment should not also replace form validation, remove labels or alter a request endpoint. Keep a recoverable version of the project before broader edits.

• Reload and confirm the layout survives.
• Test narrow and wide screens with realistic text.
• Tab through every field and submit with invalid data.
• Check the diff for unrelated changes.

Know what visual editing cannot verify

A convincing preview does not prove that data is saved, authentication is correct or the app deploys successfully. Test those behaviors independently. Editing tools may also have limits around dynamic components, third-party widgets and generated styles.

Mello is an upcoming visual editor for AI-built apps. Its public website currently shows a product direction and concept demonstrations; supported frameworks and integrations are not yet announced. The workflow above is usable today with your browser and code editor.

Further reading

• Chrome DevTools: view and change CSS