The first time I designed and built a large website, I was dismayed at how quickly my CSS file became a huge, ungainly mess. One front-end methodology would have saved me a lot of pain (and cleaned up my code): BEM (Block Element Modifier), a naming convention for CSS classes. When you’re just learning to code, using BEM can seem like overkill. But, in a professional setting, BEM (or the alternative methodology of your choice) becomes indispensable for efficiency and clarity of code. I’m a total convert, and thought I’d share some of the lessons learned along the way.