// 数字提示泡泡
._num-pop(@bg_color, @font_color, @size) {
    @font_size: @size * .6666;
    @padding: round(@size * .2);
    @min_width: @size - @padding * 2;

    .inline-block();
    vertical-align: middle;
    height: @size;
    line-height: @size;
    .border-radius(@size);
    .font-icon(@font_size, center);
    min-width: @min_width;
    padding: 0 @padding;
    color: @font_color;
    background-color: @bg_color;
    font-family: Arial, Verdana, sans-serif;
    &:empty { display: none; }
}
.num-pop(@color: @num_pop_default_background_color, @size: 20px) when (iscolor(@color)) {
    ._num-pop(@color, @num_pop_default_font_color, @size);
}
.num-pop(@color, @size: 20px) when (length(@color) > 1) {
    ._num-pop(extract(@color, 1), extract(@color, 2), @size);
}