avif / webp test

This is the demo page of webp-inline-support repository and of this blog post

CSS avif/webp background image

`picture` elements

`picture` element with avif as first source

Demo Image with avif/webp/png source chain

`picture` element with webp as first source

Demo Image with webp/avif/png source chain

`picture` element with png as first source

Demo Image with png/webp/avif source chain