// 网格化（并不是栅格化）
.width (@length) when (@length > 0) {
    .width@{length} {width: @length * 1px;}
    .max-width@{length} {max-width: @length * 1px;}
    .min-width@{length} {min-width: @length * 1px;}
    .width(@length - 10);
}
.height (@length) when (@length > 0) {
    .height@{length} {height: @length * 1px;}
    .max-height@{length} {max-height: @length * 1px;}
    .min-height@{length} {min-height: @length * 1px;}
    .height(@length - 10);
}
.line-height (@length) when (@length > 0) {
    .line-height@{length} {line-height: @length * 1px;}
    .line-height(@length - 10);
}
.width (1000);
.height (500);
.line-height (100);