Bootstrap Col-sm- 在 Medium 设备中获取效果

Question

我有一个带有<div class="col-md-8 col-sm-8 col-sm-offset-2" id="wrapper-middle"> 类的代码，问题是当我使用Medium devices 时class col-sm-8 col-sm-offset-2 生效，当我删除class col-sm-8 col-sm-offset-2 时我的代码正常工作。

我的代码如下：

<div class="row">
              <div class="col-md-8 col-sm-8 col-sm-offset-2" id="wrapper-middle">
                <div id="carousel-generic" class="carousel slide" data-ride="carousel">
                  <!-- Indicators -->
                  <ol class="carousel-indicators">
                      <li data-target="#carousel-generic" data-slide-to="0" class="active"></li>
                      <li data-target="#carousel-generic" data-slide-to="1"></li>
                      <li data-target="#carousel-generic" data-slide-to="2"></li>
                  </ol>
                  <!-- Wrapper for slides -->
                  <div class="carousel-inner" role="listbox">
                      <div class="item active">
                          <img src="images/carousel/slide1.png" alt="Error picture">
                      </div>
                      <div class="item">
                          <img src="images/carousel/slide1.png" alt="Error picture">
                      </div>
                      <div class="item">
                          <img src="images/carousel/slide1.png" alt="Error picture">
                      </div>
                  </div>
                  <!-- Controls -->
                  <a class="left carousel-control" href="#carousel-generic" role="button" data-slide="prev">
                      <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>
                      <span class="sr-only">Previous</span>
                  </a>
                  <a class="right carousel-control" href="#carousel-generic" role="button" data-slide="next">
                      <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>
                      <span class="sr-only">Next</span>
                  </a>

              </div> 
              <div id="words">
                  <header>
                      <h2><u>Lipsum</u></h2>
                  </header>
                  <article>
                      <div>
                          <p>
                              Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum. </p>

                      </div>
                  </article>

              </div>    

          </div>

Answer 1

Bootstrap col- 类在所有大于指定尺寸的屏幕尺寸上都生效——即col-sm-8 将用于sm、md 和lg，除非被覆盖。