Create a 2:1 abstract bar mark with no text. With contain, its destination at size 512 is 512 × 256 at y=128. At size 16 it is 16 × 8 at y=4. The geometry stays proportional while the opaque background fills the remaining bands.

Contain uses the smaller scale

For a 1024 × 512 source into a square of side S, min(S/1024, S/512) equals S/1024. Width becomes S and height S/2. Horizontal offset is zero; vertical offset is S/4. No source pixel is intentionally cropped and no axis is stretched independently.

Small wordmarks need special review

A complete wide mark may become only eight pixels tall in a browser tab. That is mathematically correct contain output but may be visually unusable. The right remedy can be dedicated compact artwork, not switching blindly to cover and cutting meaningful edges.

Reproduce the package

Create a simple local raster with the stated shape, choose the example fit and colours, then generate. Confirm six visible PNG dimensions, ICO entries 16/32/48, ten package files and the displayed manifest paths. Encoded byte counts may differ across browser engines, but dimensions, filenames, JSON fields, HTML paths and container structure must match the contract.