// 변수
@ColumnWidth: 60px;
@GutterWidth: 20px;
 
// 믹스인
.span(@column) {
    width: (@ColumnWidth * @column) + (@GutterWidth * (@column - 1));
}

// 스타일 적용
.container {
    width: 960px;
    margin: 0 auto;
}

.row {
    overflow: hidden;
    margin-left: 10px;
    margin-right: 10px;
}

.span_1, .span_2, .span_3, .span_4, .span_5, 
.span_6, .span_7, .span_8, .span_9, .span_10,
.span_11,.span_12{
    float: left;
}

.span_1 { .span(1); }
.span_2 { .span(2); }
.span_3 { .span(3); }
.span_4 { .span(4); }
.span_5 { .span(5); }
.span_6 { .span(6); }
.span_7 { .span(7); }
.span_8 { .span(8); }
.span_9 { .span(9); }
.span_10{ .span(10);}
.span_11{ .span(11);}
.span_12{ .span(12);}
