bors c48e6ffce5 Auto merge of #115829 - notriddle:notriddle/rustdoc-theme-css-merge, r=GuillaumeGomez
rustdoc: merge theme css into rustdoc.css

Based on https://github.com/rust-lang/rust/pull/115812#issuecomment-1717960119

Having them in separate files used to make more sense, before the migration to CSS variables made the theme files as small as they are nowadays. This is already how docs.rs and mdBook do it.

WebPageTest comparison page:

https://www.webpagetest.org/video/compare.php?tests=230913_AiDc3F_B9E,230913_AiDc7G_B9B

Filmstrip comparison:

![image](https://github.com/rust-lang/rust/assets/1593513/7ccad27b-7497-47ee-94c0-1a701b69c0c2)

Old waterfall:

![image](https://github.com/rust-lang/rust/assets/1593513/7a6e4375-226d-4205-8871-a4d775a70748)

New waterfall:

![image](https://github.com/rust-lang/rust/assets/1593513/e29112e3-84f7-417d-a250-cd6c10fa50f5)
2023-09-16 00:02:41 +00:00
..
2023-09-15 05:11:16 +00:00