try using outline: 0; on the link element. see css-tricks.com/removing-the-dotted-outline
//line 2576 of bootstrap.css
.nav-tabs > .active > a, .nav-tabs > .active > a:hover {
outline: 0;
color: #555555;
background-color: #ffffff;
border: 1px solid #ddd;
border-bottom-color: transparent;
cursor: default;
}