Clean up your CSS at the source. Write appropriate classes and group selectors well. Let go of unnecessary vendor prefixes for certain properties. It's ok to use IDs when they're needed for the sweet specificity they proffer. Utilise the power of CSS selectors like nth-of-type, nth-child, siblings and attribute selectors.

Yesterday, the world did not end. So, today is "Be kind to front-end web developers day". Today, we pretend that Bugs, Internet Explorer 8 and below, Retina Devices and low bandwidth DO NOT EXIST. We pretend that older browsers look like shit on your Web 3.0 site.