JQuery.height () not returning correct value

I have a website that needs to be full screen on every screen. For this reason I am using alot jQuery to define height, maximum height, margins, ...

I have a margin-top on the container id. When I call the height, which is the base for determining the margin-top, at the end of the script, it doesn't give me the amount I want.

While the height of the container id is wrong in var containerh, var keepert won't be right either.

var height = $(window).height();
    var width = $(window).width();
    var containerw = width * 0.9;
    var containerl = containerw * 0.5;
    var containerh = $("#container").height();
    var containert = containerh * 0.5;
    $("#container").css("margin-left", "-" + containerl + "px");
    $("#container").css("margin-top", "-" + containert + "px");
    alert($("#container").height());

      

        
        
        
      

    

* {
      margin: 0;
      padding: 0;
      overflow: hidden;
    }

    h1 {
      font-family: 'Hobo';
      color: #0070c0;
      font-weight: lighter;
    }

    font {
      color: #ed27b9;
    }

    #container {
      position: absolute;
      top: 46%;
      left: 50%;
    }

    video {
      border: 2px solid #134963;
    }

      

        
        
        
      

    

<center>
  <div id="container">
    <center>
      <h1>Leur <font>&#171; experience &#187;</font> en quelques mots...</h1>
    </center>
    <center id="boven">
      <video class="video2" frameborder="0" poster="../beelden/image39.png" webkitAllowFullScreen mozallowfullscreen allowFullScreen controls>
        <source src="../video/film1.mp4" type="video/mp4">
          <source src="../video/film1.ogg" type="video/ogg">
            <source src="../video/film1.webm" type="video/webm">
              Your browser does not support the video tag
      </video>
      <video class="video2" frameborder="0" poster="../beelden/image40.png" webkitAllowFullScreen mozallowfullscreen allowFullScreen controls>
        <source src="../video/film1.mp4" type="video/mp4">
          <source src="../video/film1.ogg" type="video/ogg">
            <source src="../video/film1.webm" type="video/webm">
              Your browser does not support the video tag
      </video>
    </center>

      

        
        
        
      

    

Can anyone help me with the top-edge and height of the container? It returns 552px on my screen, but the container id height is 546px

what is my example