The Can I Use website tells you which web features work in what browsers. Which would allow you to avoid features that might break your website for some people. There's support information for HTML5, JavaScript, CSS3, and even Web APIs as well as information for all of the web versions of browsers.
Before using some new feature make sure to look it up on Can I Use. You can judge wether or not it is safe by the amount of green boxes. If most are green, you're probably good to go - if most are red it's probably best to find some other solution.
Can I Use has lists of known problems with features in different browsers. This way you can catch or avoid common issues before it's an issue.
Sometimes features work on phone but not desktop and vise versa so it's good to keep that in mind when checking for things on Can I Use.
Can I Use offers up suggestions on other ways to achieve the same thing. If something is not well supported you can typically still find some other solution that will accomplish the same or close to the same thing.
Scroll Snap: Makes scrolling smoother. It's sort of
like magnetic points you can snap to when scrolling on your page. Works
in most modern browsers and apparently works really well with image
galleries and slideshows.
Check it out!
Container Queries: Lets you style elements based on
their parent container's size. It makes a responsive design for
individual parts. So a card could change its layout based on whether it
is in a sidebar or main content area.
Check it out!
Can I Use is a super helpful tool that shows you what web features work in different browsers. Before committing to something new in your site it would not be a bad idea to head over to Can I Use first to make sure it works for most people.