While custom CSS is allowed, Pushpages only allow for very basic CSS.
Some advanced CSS is not allowed and will be stripped by the system.

Not Allowed Example: 

border-radius: 10px 10px 10px 10px;

-moz-border-radius: 10px 10px 10px 10px;

-webkit-border-radius: 10px 10px 10px 10px;

border: 1px solid #9966cc;