//== alert
@include b(alert) {
    $bg-color: rgba(0, 0, 0, 0.7);
    
    position: absolute;
    top: 100%;
    z-index: $zindex-alert;
    margin: 6px 0 0 !important;
    padding: 8px;
    border-radius: $border-radius-base;
    color: $brand-info;
    @include rgba-bg($bg-color);
    
    // 箭头在提示框左上角
    @include m(arrow) {
        left: 0;
        
        &:before {
            position: absolute;
            top: -7px;
            border-bottom: 6px solid $bg-color;
            border-left: 6px solid transparent;
            border-right: 6px solid transparent;
            content: '';
        }
    }
    
    // 系统提示
    @include m(system) {
        position: static;
        display: inline-block;
    }
}