What is a basic front-end project for me to get a good understanding of basic html and css?

I’ve been trying to learn a front end twitter, but struggling when i try to make the web responsive. There are tons of tutorial out there, but i need some front-end suggestions and recommendations from you guys.

`@media (max-width: 1000px) {
  .widget {
     display: none;
 }
  .feed .post-body img {
     width: 55vw;
    
 }
}`

(experiment with this, tryna make the web responsive, but i think i put many element to px instead of things like vw and vh)

*Please do tell me if this questions is irrelevant for this page