Content is showing up above a fixed div when scrolling down

Question

I think this is a simple question, but i cannot get my head around it. I have a fixed div at the top of a page and when I'm scroll down to see the content, the content (text) is shown above that fixed div in a 5px margin. That margin (in black, see https://jsfiddle.net/xgtcnuL5/22/) is used for a background image in the body.

I want to keep that top margin, but I don't wanna see content there. Any ideas?

* {
  box-sizing: border-box;
}

body {
  text-align: center;
  background-color: #000;
  font: 0.9em/1.2em arial, helvetica, verdana;
  color: #4c4c4c;
}

#container {
  margin: 0 auto;
  position: relative;
  max-width: 980px;
  min-height: 700px;
  background: #fff;
  text-align: left;
  color: #4c4c4c;
}

.header {
  position: fixed;
  overflow: hidden;
  width: 90%;
  max-width: 900px;
  height: 165px;
  background-color: #fff;
  z-index: 10;
}

.top {
  margin-left: 17%;
  height: 165px;
}

.top img {
  max-width: 396px;
  margin-top: 55px;
}

.col1 {
  float: left;
  width: 17%;
  text-align: left;
  margin-top: 165px;
}

.nav {
  position: fixed;
  overflow: hidden;
  font-weight: bold;
  z-index: 11;
}

.col2 {
  float: left;
  width: 50%;
  padding: 0 20px 20px 0;
  margin-top: 165px;
}

.col3 {
  float: left;
  width: 33%;
  padding: 0 15px 15px 5px;
  text-align: left;
  font-size: 90%;
  margin-top: 165px;
}

<div id="container">
  <div class="header">
    <div class="top">
      <a href="#home"><img src="img/logo2.jpg" alt="logo" width="100%" /></a>
    </div>
  </div>
  <div style="overflow:auto">
    <div class="col1">
      <div class="nav">
      </div>
    </div>
    <div class="col2">content
    </div>
    <div class="col3">content
    </div>
  </div>
</div>

Answer 1

Add margin:0; in body CSS

* {
  box-sizing: border-box;
}

body {
  text-align: center;
  background: #000 url('../img/bg.jpg') repeat top right;
  font: 0.9em/1.2em arial, helvetica, verdana;
  color: #4c4c4c;
  margin: 0;
}

#container {
  margin: 0 auto;
  position: relative;
  max-width: 980px;
  min-height: 700px;
  background: #fff;
  text-align: left;
  color: #4c4c4c;
}

.header {
  position: fixed;
  overflow: hidden;
  width: 90%;
  max-width: 980px;
  height: 165px;
  background-color: #fff;
  z-index: 10;
}

.top {
  margin-left: 17%;
  height: 165px;
}

.top img {
  max-width: 396px;
  margin-top: 55px;
}

.col1 {
  float: left;
  width: 17%;
  text-align: left;
  margin-top: 165px;
}

.nav {
  position: fixed;
  overflow: hidden;
  font-weight: bold;
  z-index: 11;
}


.col2 {
  float: left;
  width: 50%;
  padding: 0 20px 20px 0;
  margin-top: 165px;
}

.col3 {
  float: left;
  width: 33%;
  padding: 0 15px 15px 5px;
  text-align: left;
  font-size: 90%;
  margin-top: 165px;
}

<div id="container">
  <div class="header">
    <div class="top">
      <a href="#home"><img src="img/logo2.jpg" alt="logo" width="100%" /></a>
    </div>
  </div>
  <div style="overflow:auto">
    <div class="col1">
      <div class="nav">
      </div>
    </div>
    <div class="col2">
      Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis,
      sem. Nulla consequat massa quis enim. Donec pede justo, fringilla vel, aliquet nec, vulputate eget, arcu. In enim justo, rhoncus ut, imperdiet a, venenatis vitae, justo. Nullam dictum felis eu pede mollis pretium. Integer tincidunt. Cras dapibus.
      Vivamus elementum semper nisi. Aenean vulputate eleifend tellus. Aenean leo ligula, porttitor eu, consequat vitae, eleifend ac, enim. Aliquam lorem ante, dapibus in, viverra quis, feugiat a, tellus. Phasellus viverra nulla ut metus varius laoreet.
      Quisque rutrum. Aenean imperdiet. Etiam ultricies nisi vel augue. Curabitur ullamcorper ultricies nisi. Nam eget dui.
    </div>
    <div class="col3">
      Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis,
      sem. Nulla consequat massa quis enim. Donec pede justo, fringilla vel, aliquet nec, vulputate eget, arcu. In enim justo, rhoncus ut, imperdiet a, venenatis vitae, justo. Nullam dictum felis eu pede mollis pretium. Integer tincidunt. Cras dapibus.
      Vivamus elementum semper nisi. Aenean vulputate eleifend tellus. Aenean leo ligula, porttitor eu, consequat vitae, eleifend ac, enim. Aliquam lorem ante, dapibus in, viverra quis, feugiat a, tellus. Phasellus viverra nulla ut metus varius laoreet.
      Quisque rutrum. Aenean imperdiet. Etiam ultricies nisi vel augue. Curabitur ullamcorper ultricies nisi. Nam eget dui.
    </div>
  </div>
</div>

Answer 2

* {
  box-sizing: border-box;
}

body {
  text-align: center;
  background: #000 url('../img/bg.jpg') repeat top right;
  font: 0.9em/1.2em arial, helvetica, verdana;
  color: #4c4c4c;
}

#container {
  margin: 0 auto;
  position: relative;
  max-width: 980px;
  min-height: 700px;
  background: #fff;
  text-align: left;
  color: #4c4c4c;
}

.header {
  position: fixed;
  overflow: hidden;
  width: 90%;
  max-width: 980px;
  height: 165px;
  background-color: #fff;
  z-index: 10;
}

.top {
  margin-left: 17%;
  height: 165px;
}

.top img {
  max-width: 396px;
  margin-top: 55px;
}

.col1 {
  float: left;
  width: 17%;
  text-align: left;
  margin-top: 165px;
}

.nav {
  position: fixed;
  overflow: hidden;
  font-weight: bold;
  z-index: 11;
}


.col2 {
  float: left;
  width: 50%;
  padding: 0 20px 20px 0;
  margin-top: 165px;
}

.col3 {
  float: left;
  width: 33%;
  padding: 0 15px 15px 5px;
  text-align: left;
  font-size: 90%;
  margin-top: 165px;
}

body {
 margin: 0;
}

<div id="container">
  <div class="header">
    <div class="top">
      <a href="#home"><img src="img/logo2.jpg" alt="logo" width="100%" /></a>
    </div>
  </div>
  <div style="overflow:auto">
    <div class="col1">
      <div class="nav">
      </div>
    </div>
    <div class="col2">
      Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis,
      sem. Nulla consequat massa quis enim. Donec pede justo, fringilla vel, aliquet nec, vulputate eget, arcu. In enim justo, rhoncus ut, imperdiet a, venenatis vitae, justo. Nullam dictum felis eu pede mollis pretium. Integer tincidunt. Cras dapibus.
      Vivamus elementum semper nisi. Aenean vulputate eleifend tellus. Aenean leo ligula, porttitor eu, consequat vitae, eleifend ac, enim. Aliquam lorem ante, dapibus in, viverra quis, feugiat a, tellus. Phasellus viverra nulla ut metus varius laoreet.
      Quisque rutrum. Aenean imperdiet. Etiam ultricies nisi vel augue. Curabitur ullamcorper ultricies nisi. Nam eget dui.
    </div>
    <div class="col3">
      Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis,
      sem. Nulla consequat massa quis enim. Donec pede justo, fringilla vel, aliquet nec, vulputate eget, arcu. In enim justo, rhoncus ut, imperdiet a, venenatis vitae, justo. Nullam dictum felis eu pede mollis pretium. Integer tincidunt. Cras dapibus.
      Vivamus elementum semper nisi. Aenean vulputate eleifend tellus. Aenean leo ligula, porttitor eu, consequat vitae, eleifend ac, enim. Aliquam lorem ante, dapibus in, viverra quis, feugiat a, tellus. Phasellus viverra nulla ut metus varius laoreet.
      Quisque rutrum. Aenean imperdiet. Etiam ultricies nisi vel augue. Curabitur ullamcorper ultricies nisi. Nam eget dui.
    </div>
  </div>
</div>

Hope below code will help to you

body {
  margin: 0;
}

Thanks