text-decoration: none; not working

Hi I would like to change the look of a highlighted element which is also a link to another page. See "support us" button with orange/red background here. Because I have made it a link, the theme automatically underlines it. How can I get rid of that underline? Also how can I make it respond to hovering (since the underline will be gone)? Could I change the colour of the writing? or the colour of the highlight? or both? Also how can I make the other highlighted element on that page respond to hovering above it? Specifically I would like the text to change colour (i.e. have the same behaviour as the website title) Thanks TB