css - Container overlapping to header -

i have problem container, overlapping header, how adjust in css? should under header little margin between header , container.

see screenshot here

    #myheader {       position: fixed;       top: 0;       left: 0;       width: 100%;       z-index: 100;       background-color: yellow;        box-shadow: 0px 2px 3px  #888888;       height: 150px;         opacity:0.95;       filter:alpha(opacity=10);       }  #mycontent {     padding-top: 10px;  }  #mycontent .row {     background-color: #fff; }  #mycontent h1{   margin-top: 0;  }           <section id="mycontent">         <div class="container">             <div class="row">                 <div class="col-sm-8 col-md-8 col-lg-8">                     <div>                         <br />                         <?php if ($breadcrumb): ?>                           <div id="breadcrumb"><?php print $breadcrumb; ?></div>                         <?php endif; ?>                          <?php print $messages; ?>                          <div id="content" class="column"><div class="section">                           <a id="main-content"></a>                           <?php print render($title_prefix); ?>                           <?php if ($title): ?><h1 class="title" id="page-title"><?php print $title; ?></h1><?php endif; ?>                           <?php print render($title_suffix); ?>                           <?php if ($tabs): ?><div class="tabs"><?php print render($tabs); ?></div><?php endif; ?>                           <?php print render($page['help']); ?>                           <?php if ($action_links): ?><ul class="action-links"><?php print render($action_links); ?></ul><?php endif; ?>                           <?php print render($page['content']); ?>                           <?php print $feed_icons; ?>                         </div></div> <!-- /.section, /#content -->                          <?php if($is_front):?>                         <h2>mission & vision<br /></h2>                         <!-- <img src="<?php print(path_to_theme()); ?>/images/bottom.jpg" alt="" class="img-thumbnail pull-left" style="margin-right: 10px;" /> -->                         <div>                             our company comes trade few years ago beginning start professional projects.                             our not satisfied result. needs perfect.                             <br /><br />                             that's why teach our employers still make them best in region.                             every 2 years give our employers test new technologies make sure leaders on market.                             <br /><br />                             there no excuse fails. our standards high every time first rule quality.                             <br /><br />                             can see in photogallery our references more. our company in touch partners qint, tsn-d or finishline...                             <br /><br />                             come our company take prospects see if our portfolio fit vision , after can find best way                             how realize together!                             <br /><br />                         </div>                         <?php endif; ?>                     </div>                 </div> 

the header should inside container , give fixed width container

here example:

.container{ width:100%; max-width:500px; margin:0 auto; position:relative; background-color:yellow; padding-top:100px;}  .header{ width:100%; max-width:500px; margin-left:-250px; left:50%;  height:100px; background-color:red; position:fixed; top:0px; text-align:center;} 

<div class="container">        <div class="header">header</div>          container<br/>          container<br/>          container<br/>          container<br/>          container<br/>          container<br/>      </div>