I used the ''Bootstrap'' example for Fixed Navbar\\
<code>
<!-- Fixed navbar -->
<nav class="navbar navbar-default navbar-fixed-top">
 <div class="container">
  <div class="navbar-header">
   <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
    <span class="sr-only">Toggle navigation</span>
    <span class="icon-bar"></span>
    <span class="icon-bar"></span>
    <span class="icon-bar"></span>
   </button>
   <a class="navbar-brand" href="#">MIER</a>
  </div>
  <div id="navbar" class="navbar-collapse collapse">
   <ul class="nav navbar-nav">
    <li class="active"><a href="#">Home</a></li>
    <li><a href="#about">About</a></li>
    <li><a href="#contact">Contact</a></li>
    <li class="dropdown">
     <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Dropdown <span class="caret"></span></a>
     <ul class="dropdown-menu">
      <li><a href="#">Action</a></li>
      <li><a href="#">Another action</a></li>
      <li><a href="#">Something else here</a></li>
      <li role="separator" class="divider"></li>
      <li class="dropdown-header">Nav header</li>
      <li><a href="#">Separated link</a></li>
      <li><a href="#">One more separated link</a></li>
     </ul>
    </li>
   </ul>
   <span class="nav navbar-nav navbar-right">
    <form method="get" action="<$mt:CGIPath$><$mt:SearchScript$>">
     <input type="text" id="search" class="ti" name="search" value="<MTIfStatic><mt:IfStraightSearch><$mt:SearchString$></mt:IfStraightSearch></MTIfStatic>" />
     <input type="hidden" name="IncludeBlogs" value="<$mt:WebsiteID$><mt:WebsiteHasBlog><mt:Blogs include_blogs="children">,<mt:BlogID></mt:Blogs></mt:WebsiteHasBlog>" />
     <input type="hidden" name="limit" value="<$mt:SearchMaxResults$>" />
     <input type="submit" accesskey="4" value="<__trans phrase="Search">" />
    </form>
   </span>
  </div><!--/.nav-collapse -->
 </div>
</nav>
</code>

while putting this in ''Stylesheet''\\
<code>
body {
  min-height: 2000px;
}

.navbar-static-top {
  margin-bottom: 19px;
}
</code>