title: Collapsing margin issue
body: <p>I trying to solve margin collapse issue. 
  I don't understand why paragraph overlap. 
  I really wan to know reason why this problem occur.
  I think It's like collapsing margin issue. </p>
  
  <p>please take look at blow</p>
  
  <p><a href="https://i.stack.imgur.com/eNNRL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eNNRL.png" alt="enter image description here"></a></p>
  
  <p>this is my html</p>
  
  <pre><code>    &lt;div class="menu_list open"&gt;
        &lt;ul&gt;
          &lt;li&gt;&lt;a href="#/" class="router-link-active"&gt;Home&lt;/a&gt;&lt;/li&gt;
          &lt;li&gt;&lt;a href="#/Story" &gt;Story&lt;/a&gt;&lt;/li&gt;
          &lt;li&gt;&lt;a href="#/Brands" &gt;Brands&lt;/a&gt;&lt;/li&gt;
          &lt;li&gt;&lt;a href="#/news" &gt;News&lt;/a&gt;&lt;/li&gt;
          &lt;li&gt;&lt;a href="#/contact" &gt;Contact&lt;/a&gt;&lt;/li&gt;
        &lt;/ul&gt;
      &lt;/div&gt;
      &lt;div  class="company_detail_container container" style="background: #c9bbbb;"&gt;
  &lt;main  class="company_detail"&gt;
  
      &lt;p &gt;
      The new legislation would also sharply limit President Donald Trump's ability to lift any sanctions against Russia.
      He has previously said he needs diplomatic leeway with the Kremlin.
      Mr Trump's time in office has been dogged by claims that Russia tried to influence last year's US election.
      Moscow denies any wrongdoing but several US investigations are looking into whether anyone in the Trump campaign colluded with Russian officials.            &lt;/p&gt;
  
  &lt;/main&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>this is my css </p>
  
  <pre><code>.menu_list{
    width: 100%;
    height: 200px;
    top: 0;
    left: 0;
    opacity: 1;
    position: relative;
    padding: 10px;
  }  
  
  .menu_list li{
        display: block;
      list-style: none;
      padding: 10px;
      border-bottom: 1px solid black;
      text-align: center;
  }
  p {
      margin: 0 0 10px;
  }
  </code></pre>
  
  <p>please give me any idea</p>
  
  <p><a href="https://codepen.io/jeonghu/pen/KvKPPO?editors=1100" rel="nofollow noreferrer">https://codepen.io/jeonghu/pen/KvKPPO?editors=1100</a></p>