// 字符×按钮
.button-x(@color: #000, @size: 20px, @active_class: active) {
    .appearance-none();
    .inline-block();
    vertical-align: middle;
    cursor: pointer;
    text-decoration: none;
    font-size: @size;
    font-weight: 700;
    line-height: 1;
    color: @color;
    text-shadow: 0 1px 0 #fff;
    .size(1em);
    .opacity(.2);

    &:after {
        content: '×';
        display: block;
        line-height: 1;
        text-align: center;
        position: relative;
        top: -0.06em;
    }

    .hover-or-active({
        .opacity(.5);
    }, @active_class);
}