Fix some visual, bugs and add some smooth animations on tabs

.tab-bar{
    padding: 0;
    .tab{
        border-left: 1px solid silver;
        transition:.25s all;
        &:first-of-type{border-left: 0;}
        &:hover{
            border-color:silver;
            background-color: #555;
        }
        .title, .close-icon{color:#fff;}
    }
}