// 关闭按钮
.icon-close(@size: 30px, @radius: 100%) when (isnumber(extract(@size, 1))) {
    .icon-add(white black white, @size, @radius);
    .rotate(45deg);
}
.icon-close(@color, @size: 30px, @radius: 100%) when (iscolor(extract(@color, 1))) {
    .icon-add(@color, @size, @radius);
    .rotate(45deg);
}