This is another novice question from me. I am just trying to be curious here. Also, this may help many beginner web developer.
Just learn more JavaScript. Understand React and Redux and try to make sense ofprototypal inheritance and functional programming in JavaScript. Have a look at Vue. laracasts.com/series/learning-vue-step-by-step
Learn some frameworks or what it's called.
For CSS:
For Javascript:
If you don't want to learn backend such as .NET or PHP. Learn about RESTful APIs so you can make frontend solutions that communicate with the backend API through Javascript (VueJS has the vue-resources).
Most important of all, be excellent in these things you already learned and have a birds eye understand of how it's structured.
For my case:
Emil Moe
Senior Data Engineer
Mario Giambanco
Director of User Experience Development
(early 90s)
(Early 2000s)
(2010s)