I believe padding is the answer. I have mine padded ut a little, you can see it here.
https://www.spottedhaggis.com/jemima
My bettercategoris css is as follows
.betterCategories, .betterDocuments, .betterEzpages,
.betterBestsellers {
border-top: 1px solid #ffffff;
padding-bottom: 4px;
padding-top: 4px;
font-size: 12px;
font-family: "Trebuchet MS";
text-align: center;
font-weight: bold;
letter-spacing: 2px;
}
.betterInformation, .betterMoreinformation {
padding: 2px;
padding-bottom: 2px;
color: #FFFFFF;
font-size: 13px;
font-family: "Trebuchet MS";
text-align: center;
font-weight: 500;
}
.betterCategories a, .betterCategories a:visited,
.betterDocuments a, .betterDocuments a:visited,
.betterEzpages a, .betterEzpages a:visited,
.betterBestsellers a, .betterBestsellers a:visited {
display: block;
background-color: #6DCFF6;
border-top: 2px solid #ffffff;
padding: 4px;
color: #ffffff;
font-family: "Trebuchet MS";
font-size: 13px;
font-weight: bold;
}
.betterInformation a, .betterInformation a:visited,
.betterMoreinformation a, .betterMoreinformation a:visited
{
display: block;
border-top: 2px solid #ffffff;
padding: 2px;
color: #84C46F;
font-family: "Trebuchet MS";
font-size: 13px;
text-align: center;
font-weight: bold;
}
.betterCategories a:hover, .betterCategories a:active,
.betterDocuments a:hover, .betterDocuments a:active,
.betterEzpages a:hover, .betterEzpages a:active,
.betterBestsellers a:hover, .betterBestsellers a:active {
background-color: #AAD69B;
color: #FFFFFF;
font-family: "Trebuchet MS";
font-size: 13px;
}
.betterInformation a:hover, .betterInformation a:active,
.betterMoreinformation a:hover, .betterMoreinformation a:active
{
display: block;
border-top: 2px solid #ffffff;
padding: 2px;
color: #666666;
font-family: "Trebuchet MS";
font-size: 13px;
text-align: center;
font-weight: bold;
}
/*
.category-subs-selected, .category-subs-selected a:hover {
font-weight: bold;
text-decoration: none;
}
*/