I can’t tell you how many Front End developer interviews I have gone through with out a single question about CSS. I spent hours at one interview white-boarding algorithm after algorithm till I finally said . “This is a interview for a Front End developer right? Because so far no one has asked me a single question about HTML and CSS, which is half my job.” What if I have no idea what a rem unit is or no idea how css specificity works? There seems to be this assumption that you can skate by on mediocre CSS and HTML skills as long as you are a JS rockstar.