Whenever you get confused over html syntax or css rules, this is the first website you should surf.
When the code doesn’t work, look for questions on that topic in the website. 99% of your problems will be solved.
Want to put some cool animations in your page? Why not check out some of the coolest animations, with all the codes here?
Learning is so much easier watching videos. There are so many awesome channels in youtube where you can learn to code.
While building website in php, this is the single most helpful document ever.
Building responsive websites is now the RULE rather than the EXCEPTION. Bootstrap is the most popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web. So this is something you need to refer all the time.