If you are interested in CSS…

If you are interested in CSS and performance, then this brain dump from Harry Roberts is well worth your time. Harry covers the “Critical CSS” pattern, in which youΒ identify all of the styles needed for Start Render (commonly the styles needed for everything above the fold), and then you inline them inΒ <style>Β tags in the <head> your document and asynchronously load the remaining stylesheet off of the Critical Path.