I wouldn’t declare CSS dead though. Some folks, like myself, continue to do things the right (IMHO) way. I sometimes even consider creating a new site like CSS Zen Garden (haven’t bothered to check whether such already exists)... imagine the creations people could make nowadays.
I also use Bootstrap, and I love it, but I don’t use it to design my apps / websites; I use it for its utilities (responsive utilities, form styles, etc.). I realize there are smaller frameworks for this purpose, and I sometimes use them also. I still design most of the internal layout from scratch (e.g., I don’t use “cards” and other shortcuts to bypass meaningful design, etc.).