Comment by l3l_aze

Can only recommend HTML5/CSS3/ECMAScript (modern JS) as I'm not deep into the backend yet. No matter what else is piled on top they are the core, and others are using them on some level. The languages you use are less important than the concepts you will learn, in the long run. Because if you know how to do something in one lang/stack you can do it in any comparable alternative provided enough documentation/StackOverflow and time. I went for languages instead and though I can "just read" some code I don't fully understand in random languages, I also don't have as good of a grasp on my preferred & used languages.