Top navbar overlaps with main content

I'm converting my landing page from Bootstrap to Semantic-UI. The page has a position fixed top navbar. The main content is divided in two columns (3-cols and 9-cols). The left column is used to show a sidebar and the right column is used for current content.

I tried to copy and paste the demo page of Semantic-UI. The navbar is 45px high. I noticed that the first 45px of main content is overlapped.

<link href="//semantic-ui.com/dist/semantic.min.css" rel="stylesheet"/>
<script src="//semantic-ui.com/dist/semantic.min.js"></script>

<div id="navbar" class="ui fixed inverted main menu">
  <div class="container">
    <div class="title item">
      <b>Dashboard</b>
    </div>
  </div>
</div>

<div id="maincontent" class="ui bottom attached segment pushable">
    
  <div id="sidebar" class="ui visible left vertical sidebar menu">
    <a class="item">First Item</a>
    <a class="item">Second Item</a>
    <a class="item">Third Item</a>
    <a class="item">Fourth Item</a>
    <a class="item">Fifth Item</a>
  </div>
    
  <div id="content" class="pusher">
    <div class="ui basic segment">
      <h3 class="ui header">Application Content</h3>
      <p>First paragraph...</p>
      <p>Second paragraph...</p>
      <p>Third paragraph...</p>
    </div>
  </div>

</div>

My current workaround is to add a 45px high placeholder after navbar.

<div style="height:45px"></div>

I'm pretty sure there are some good css style names can fix the content overlapping.

The solution is much simpler. You just need to add a padding to your main container:

<div id="navbar" class="ui fixed inverted main menu">
 <!-- header content here -->
</div>
<div id="content" class="ui container">
 <!-- main content here -->   
</div>

And add in your CSS:

.ui#content{
  // padding should be the same as header height
  padding-top: 55px;
}