.nav-tabs{
    border-bottom: 0;
}
.tab-button > i{
    margin-left: 15px;
    -webkit-transition: transform .5s;
    -moz-transition: transform .5s;
    -ms-transition: transform .5s;
    -o-transition: transform .5s;
    transition: transform .5s;

    -webkit-transform-origin: 50% 50%;
    -moz-transform-origin: 50% 50%;
    -ms-transform-origin: 50% 50%;
    -o-transform-origin: 50% 50%;
    transform-origin: 50% 50%;

    
}

.tab-button.active > i{
    -webkit-transform: rotate(-180deg);
    -moz-transform: rotate(-180deg);
    -ms-transform: rotate(-180deg);
    -o-transform: rotate(-180deg);
    transform: rotate(-180deg);
}