自動レイアウトの列

Window Width :

等幅（Equal-width）

1 of 2 (class="col")

2 of 2 (class="col")

1 of 3 (class="col")

2 of 3 (class="col")

3 of 3 (class="col")

<div class="container">
  <div class="row">
    <div class="col">
      1 of 2
    </div>
    <div class="col">
      2 of 2
    </div>
  </div>
  <div class="row">
    <div class="col">
      1 of 3
    </div>
    <div class="col">
      2 of 3
    </div>
    <div class="col">
      3 of 3
    </div>
  </div>
</div>

1 of 2 (class="col-md")

2 of 2 (class="col-md")

1 of 3 (class="col-md")

2 of 3 (class="col-md")

3 of 3 (class="col-md")

<div class="container">
  <div class="row">
    <div class="col-md">
      1 of 2
    </div>
    <div class="col-md">
      2 of 2
    </div>
  </div>
  <div class="row">
    <div class="col-md">
      1 of 3
    </div>
    <div class="col-md">
      2 of 3
    </div>
    <div class="col-md">
      3 of 3
    </div>
  </div>
</div>