I still hand write everything in html css and make progressive enhancements. I like layouts that are still readable if you turn off css and javascript, using meaningfull/semantic html. I do like a lot of the stuff that have been added to css, it makes my life easier. So i suggest starting out with just html5, then do the fancy stuff in css. One line of css can usually replace what you needed 20 lines of javascript to do before. Html and css are lagging far behind though eg. You cant define how a json file should be rendered using just html and css. Thus all the frameworks like React to close the gap. If possible though keep things simple enough that you dont have to rely on heavy javascrip.