Admin CP -> Appearance -> Templates -> EXTRA.css
Add this code. Use any padding numbers you want. Below are the default values for the public and account tabs:
Code:
.navTabs .publicTabs .navLink
{
padding: 0 15px;
}
.navTabs .visitorTabs .navLink
{
padding: 0 10px;
}
And this is for the secondary nav links (under the selected tab):
Code:
.navTabs .navTab.selected .tabLinks a
{
padding: 1px 10px;
}