It's not as hard as it seems! Use this bit of CSS to create a more customized appearance:
.ss_links a{border: solid 4px #ff0000; /* border designates the border color, size, and line style */
background:#000000; /* this controls the background color of the link */
font-family: arial, sans-serif; /* font-family determines the web-safe font used for the link name */
color:#ffffff; /* color controls the color of the text in the links widget */
font-size: 14px; /* font-size determines the size of the text in the links widget */
border-radius: 10px; /* border-radius helps to create rounded corners, for a more button-like look. The larger the number, the more rounded the corners. If you don't want rounded corners, change the border-radius to 0px */}
You can even change the color of the button when you hover over the link, here's the CSS:
.ss_links a:hover{background:#585858; /* this controls the background color of the link when you hover over it */}
You can change the Hex Values, pixel dimensions, border styles, and the font-family to suit your tab.
Here are a few great references to help you customize:
Hex Value Guide: http://www.w3schools.com/cssref/css_colors.asp
Guide to web-safe fonts: http://www.w3schools.com/cssref/css_websafe_fonts.asp.