_The evil that CSS do:- Browsers block rendering until all CSS arrives. With the worst possible experience: white page.- Browsers download CSS they don't need, e.g. print, tv, device-ratio... And most browsers block rendering because of these too- Sometimes CSS blocks the other downloads too (not just block rendering, but block images and scripts that follow) - when followed by an inline SCRIPT or when it's a CSS in conditional comment for IE_Read the full artcile by Stoyan Stefanov here.