[b]Learn to create modern and compatible websites. HTML and CSS are standardized - But Browsers are not! You cannot afford to ignore browser compatibility issues.
Learn which best practices you can follow to minimize cross-browser and cross-device compatibility issues.
Even if you need to maintain compatibility with older browsers you can use modern technologies like HTML 5 and CSS 3.
A good cross-browser testing solution can greatly reduce your time spent testing. Learn what the best available solutions are.