When you see the following in your CSS
It makes sense to convert it to this.
margin: 10px 20px;
It’s cleaner and takes up less space.
There are a lot of ways you can optimize your CSS in this way. I'm not talking about compression, but optimization.
Today, The Daily Blog Tips site linked to a website called CleanCSS that can perform many of these optimizations for you. For example, feed it the above CSS and it will make that conversion. Very nice!