That's ten minutes on the naughty step for you.
Without knowing how it was before, and assuming that the buttons and hover states were the same as other areas of the page, I think that the rules might have been:
configurable.css (line 70)
.ps_main a, .ps_main a:link, .ps_main a:visited, .ps_main a:active {
background-color: #807068;
color: #FFFFFF;
}
configurable.css (line 74)
.ps_main a:hover {
background-color: #CC1776;
}
If you wanted to remove the underline, each would need to have a text-decoration:none line.
I don't know if the whole navigation area had any background, but if it did it could have been in default.css at about line 39, or configurable.css (line 58) for just the button nav area.