Are there any pros and cons of using plain css over bootstrap ?
from my humble knowledge that plain css make you build everything from scratch but bootstrap and other framework help you to build on them so it save you huge time unless if you want to build custom one that those framwork doesnot help you to build it
it rare but still exist so many build over framwork and customize it when need and they even can make some of the element customized by their self unless if you need to customiz everything as mentioned above
hope that help and have a nice day