&gt; The performance differences, between CSS styles applied from a JS file and a CSS file are very small on modern browsers, with JS being faster sometime.<p>False, JS have to be interpreted and you have issue with document not being fully loaded.  And CSS is easy to parse, faster to parse and &quot;run&quot; than JS.  No, saying that JS is faster than CSS is just false.<p>&gt; JS files are cached.<p>CSS too, and even can be prerendered.  And CSS works when JS is disabled.<p>&gt; Preprocessors are not fine, they complicate and slow down the development process.<p>That&#x27;s not an argument at all because with the right tool its just like using a compiler.  See &quot;make&quot; for example.  Also you have to see how much you gain with the preprocessor, maybe loosing 0.01ms per &quot;make&quot; is worse it since you write code 1.2 times faster...<p>&gt; Inlining CSS is not stupid, OP discusses the numerous advantages it brings...<p>And do not highlight the obvious disadvantages.