Most browser compatibility issues come from JavaScript, not HTML/CSS. Unless you want to support ancient/dead browsers (like Internet Explorer or non-HTML5 browsers), it’s very likely there won’t be any issues.
MDN has a compatibility table for every HTML tag and CSS property. For a simple static site I would just manually check there.


























I agree on the no pics rule but penalizing for upvoting won’t work like you would expect. Many people browsing their feed won’t pay attention to the community the post is in and just vote based on what they see. And even if they notice the community, you can’t expect everyone to know/remember the rules of every community.