At.js bootstrap style

atjs.less

.atwho-view {
    top: 0;
    left: 0;
    position: absolute;
    display: none;
    overflow: auto;

    ul {
        &:extend(.dropdown-menu);
        position: relative;
        display: block;

        > li a {
            &:extend(.dropdown-menu > li > a);
        }
    }

    .cur {
        a {
            &:extend(.dropdown-menu > .active > a);
       }

        .list-help-text {
            &:extend(.list-help-text.active);
        }
    }
}