First, our dear friend HTML. Most people say HTML is the "skeleton" of your website and I agree. HTML allows you to structure and give a shape to your page, like the skeleton of your body. It is really important to learn and absorb it completely, you must be able to understand how it works and how to manipulate it for sure.
Beautiful and stylish CSS, the perfect words to define CSS. If you have a skeleton, so, you need a skin on it, a tool to beautify this hollow and empty skeleton. Once you master it, once you are able to apply content box, animations, flexbox, grid, etc. Probably, you think you're a master of CSS, let me broke your little heart and tell you that there's a wonderful world beyond CSS, from preprocessors such as sass, stylus and less to frameworks such as bootstrap, materialize, tailwind and so much more to learn. Don't worry, I promise you it's really cool.
To sum up, do not be scared of technologies, love them indeed. Doing your own research and find out what's your favorite and what you'll be using to grow as a web developer. Master the basics and go further. 🚀