The first layout tag under <gui> defines the canvas. Two patterns cover all cases.

Root Canvas

conceptcanvas patterns

The first layout tag under <gui> defines the canvas. Two patterns cover all cases.

Attr	Type	Description
`<col w="390">`	`pattern`	Content-driven screen, AI-authored. h absent — hugs children.
`<frame w="390" h="844">`	`pattern`	Fixed artboard, Figma export. h required.

Default to <col> — it cannot clip content. <frame> children are absolutely positioned. <col> children flow vertically.

Both patterns

<!-- content-driven: h absent, hugs children -->
<gui version="0.2" name="Feed">
  <col w="390" fill="#fff" gap="0">
    ...
  </col>
</gui>

<!-- fixed artboard: h required, children absolute -->
<gui version="0.2" name="Splash">
  <frame w="390" h="844" fill="#000">
    <img x="0" y="0" src="assets/bg.webp" w="390" h="844" fit="cover" />
    <text x="24" y="720" value="Welcome" font-size="32"
          font-weight="700" fill="#fff" />
  </frame>
</gui>