data URIs or data URL

 https://css-tricks.com/data-uris/

裡的

Use this online conversion tool.

https://websemantics.uk/tools/image-to-data-uri-converter/

裡的

If you’re converting SVG to data-URI to embed into a style sheet or HTML please consider this method instead: Cross browser SVG URI background-images.

https://websemantics.uk/articles/embedding-svg-cross-browser/

看到  The current solution is svg4everybody