Background colour

The canvas paper colour is a per-scene viewport setting: viewport.background (any CSS colour). Absent means DEFAULT_CANVAS_BACKGROUND (#f5f5f5). It serialises with the document and reaches "with background" exports.

Setting it

import { setViewport, canvasBackgroundOf } from "@oh-just-another/scene";

const { scene: dark } = setViewport(scene, { ...scene.viewport, background: "#4a4a4a" });
canvasBackgroundOf(dark.viewport); // "#4a4a4a"
canvasBackgroundOf(scene.viewport); // "#f5f5f5"

Through the editor — part of history, so ⌘Z restores the previous colour; null clears the field:

editor.setCanvasBackground("#000000");
editor.canvasBackground; // "#000000"
editor.setCanvasBackground(null); // back to the default paper

In the UI

Board › Background colour lists CANVAS_BACKGROUND_PRESETS (@oh-just-another/editor): White, Light gray (default), Gray, Dark gray, Black, Light blue. The <Editor> root's --du-canvas-bg follows the scene, so a document looks the same in every host; without a colour in the document the stylesheet token stays in charge. The dark chrome theme never recolours the paper.

Exports

PNG "with background" uses the scene colour (falling back to the host's --du-canvas-bg), and headless renderToPng uses it unless background is passed. SVG and transparent PNG carry no paper.