Grid System

文件结构

​ grid-allin.less——合并文件，包含底下三个文件的版本。

​ grid.less——主文件，请编译此文件。

​ mixin.less——混入文件，定义变量和混入类。

​ grid-framework.less——混入文件，定义逻辑和循环方法。

mixin.less

变量

临界点：@screen-xs:480px @screen-sm:768px @screen-md:992px @screen-lg:1200px

最大临界点：@screen-xs-max @screen-sm-max @screen-md-max

列数：@grid-columns:12

间隙：@grid-gutter-width:30px

// Generate the small columns
.make-sm-column(@columns; @gutter: @grid-gutter-width) {
  position: relative;
  min-height: 1px;
  padding-left:  (@gutter / 2);
  padding-right: (@gutter / 2);

  @media (min-width: @screen-sm-min) {
    float: left;
    width: percentage((@columns / @grid-columns));
  }
}
.make-sm-column-offset(@columns) {
  @media (min-width: @screen-sm-min) {
    margin-left: percentage((@columns / @grid-columns));
  }
}
.make-sm-column-push(@columns) {
  @media (min-width: @screen-sm-min) {
    left: percentage((@columns / @grid-columns));
  }
}
.make-sm-column-pull(@columns) {
  @media (min-width: @screen-sm-min) {
    right: percentage((@columns / @grid-columns));
  }
}

Grid-framework.less

// Common styles for all sizes of grid columns, widths 1-12

.make-grid-columns() {
  // Common styles for all sizes of grid columns, widths 1-12
  .col(@index) { // initial
    @item: ~".col-xs-@{index}, .col-sm-@{index}, .col-md-@{index}, .col-lg-@{index}";
    .col((@index + 1), @item);
  }
  .col(@index, @list) when (@index =< @grid-columns) { // general; "=<" isn't a typo
    @item: ~".col-xs-@{index}, .col-sm-@{index}, .col-md-@{index}, .col-lg-@{index}";
    .col((@index + 1), ~"@{list}, @{item}");
  }
  .col(@index, @list) when (@index > @grid-columns) { // terminal
    @{list} {
      position: relative;
      // Prevent columns from collapsing when empty
      min-height: 1px;
      // Inner gutter via padding
      padding-left:  ceil((@grid-gutter-width / 2));
      padding-right: floor((@grid-gutter-width / 2));
    }
  }
  .col(1); // kickstart it
}

编译成：

.col-xs-1, .col-sm-1, .col-md-1, .col-lg-1, .col-xs-2, .col-sm-2, .col-md-2, .col-lg-2, .col-xs-3, .col-sm-3, .col-md-3, .col-lg-3, .col-xs-4, .col-sm-4, .col-md-4, .col-lg-4, .col-xs-5, .col-sm-5, .col-md-5, .col-lg-5, .col-xs-6, .col-sm-6, .col-md-6, .col-lg-6, .col-xs-7, .col-sm-7, .col-md-7, .col-lg-7, .col-xs-8, .col-sm-8, .col-md-8, .col-lg-8, .col-xs-9, .col-sm-9, .col-md-9, .col-lg-9, .col-xs-10, .col-sm-10, .col-md-10, .col-lg-10, .col-xs-11, .col-sm-11, .col-md-11, .col-lg-11, .col-xs-12, .col-sm-12, .col-md-12, .col-lg-12 {
  position: relative;
  min-height: 1px;
  padding-left: 15px;
  padding-right: 15px;
}