I think it would depend on how much time you are willing to put in and how far you want to go. If you are primarily a back end developer and you just want to q

I think it would depend on how much time you are willing to put in and how far you want to go. If you are primarily a back end developer and you just want to quickly throw down a few prototype pages. If you will never really need more than that, just spending a couple of hours learning bootstrap will be a much better use of time than spending a few weeks learning all the intricacies of css. I spent years fighting with css. It was such a relief when Bootstrap and friends came out and just removed a whole layer of complexity from my occasional forays into the front end.