What's the point of valid CSS/HTML?

Question

If I\'ve tested my pages in most major browsers, why would I need to maintain a validated code? I want to use box-shadows and corner radius if they\'re supported in WebKit b

Answer 1

You can't test in browsers that haven't been released yet!

Browsers tend to become more standards compliant over time. If you write standards-compliant webpages, they're more likely to still work in the next version of all existing browsers.