Thread:Project:Support desk/Why don't mediawiki use css sprite on vector skins?/reply (2)

No, customizability was not the reason not to use sprites.

In the past the Vector skin did use some sprites, but since MediaWiki has ResourceLoader we've de-sprited everything. ResourceLoader comes with a feature to convert referenced images into embedded Data URIs. That gives the power of sprites (loading all images in a single request) and the power of separate images (customizability).

Data URI embedding is even better than sprites also in terms of requests, as with a sprite there is a request for the CSS file and one for the sprite. With data URL embedding there is only request for the CSS file and that contains all images inside of it.

See also. And the two presentations on the "more info" list here.