title: Remove padding between div in twitter bootstrap
body: <p>I'm new to bootstrap 3. I want to divide a row into 8-column and 4-column, also add the background for the row</p>
  
  <pre><code>            &lt;div class="row" &gt;
                  &lt;div class="col-sm-8"&gt;
                      &lt;div class="abc" style="background:blue"&gt;a&lt;/div&gt;
                  &lt;/div&gt;
                  &lt;div class="col-sm-4"&gt;
                      &lt;div class="abc" style="background:blue; border:1px solid red"&gt;b&lt;/div&gt;
                  &lt;/div&gt;
              &lt;/div&gt;
  </code></pre>
  
  <p>but I dont know why there is a blank space between two column. So, how can I remove the blank. Below is a image for more detail.<img src="https://i.stack.imgur.com/9O3d7.png" alt="Your picture"></p>
  
  <p>ps: sorry for my bad english</p>