For those that need help trying to validate your webpages to valid CSS/HTML that all standard browsers will support. Here is a small list of great resources.
World Wide Web Consortium: these people are the granddaddy of web standards & offer many great tools to help you validate your webpages. Such the CSS Validator which scans your CSS code and gives you an idea of any errors that may be present.
Web Page Analyzer: This service scans your webpage and gives you a report on the speed the page takes to load and tells you whether or not it is suitable and what it recomends you change to keep your website at an excellent speed.
CleanCSS: This website offers you a quick way to slim your CSS Stylesheet down in file size, just past your CSS into the box. Select which options you want to change and click Process CSS.