Section background overflowing into another section

Question

I apologize in advance for this somewhat lengthy explanation. I am trying to create a website such as http://melaniedaveid.com/ to improve my coding abilities. I created the first section page and it turned out great. But when I added another section, the previous section didn't fill up the whole page anymore (picture: https://i.sstatic.net/Z3r5v.jpg).

In order to solve this I gave full height to the first sections ID:

#header {
height: 100%;}

This fixed the problem(https://i.sstatic.net/6YNVz.jpg) but now when I resize my browser the second section over flows into my first, covering the text(https://i.sstatic.net/TowAk.jpg). Any suggestions/leads would be greatly appreciated!

body {
  background: linear-gradient(rgba(0, 0, 0, 0.7), rgba(0, 0, 0, 0.7)), url('/img/roses.jpg') no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
  font-size: 20px;
  height: 100vh;
}

/*------------------------------------------------  HOME PAGE  ------------------------------------------------------------------*/

/*------------------------------
HEADING TEXT
-------------------------------*/
.name h1 {
  font-family: 'Muli', sans-serif;
  font-size: 500%;
  font-weight: 300;
  text-align: center;
  padding-top: 10%;
  color: #ecf0f1;
  font-family: 'Cormorant Garamond', serif;
}

.name p {
  font-family: 'Play', sans-serif;
  font-size: 130%;
  text-align: center;
  padding-top: 5%;
  color: #ecf0f1;
  font-family: 'Merriweather', serif;
  font-weight: 300;
  padding-right: 10%;
  padding-left: 10%;
}

/*------------------------------
Nav Bar
-------------------------------*/

.navigation p {
  display: inline;
  font-family: 'Play', sans-serif;
  color: #ecf0f1;
}

.navigation {
  text-align: center;
  padding-top: 15%;
}

.contents,
.contents:hover {
  text-decoration: none;
  color: #ecf0f1;
  font-family: 'Delius Unicase', cursive;
}

/*------------------------------------------------  ABOUT PAGE  ------------------------------------------------------------------*/

/*------------------------------
About Heading
-------------------------------*/

#about {
  background-color: black;
  background-size: cover;
  height: 100%;

}

#header {
  height: 100%;
}

<section id="header">  <!-------------------------  HOME PAGE  -------------------------->


  <div class="container">
    <div class="row">
      <div class="col-xs-12 name">
        <h1>Temple Naylor</h1>
      </div>
    </div>

    <div class="row">
      <div class="col-xs-12 name">
        <p>I create Web-designs with a sense of Feng-Shui in mind; resulting for a intuitive, responsive, harmonious, experience for users across the world.</p>
      </div>
    </div>

    <div class="row">
      <div class="col-xs-12 navigation hidden-sm-down">
        <p><a class="contents" href="#">ABOUT</a> / </p>
        <p><a class="contents" href="#">WORK</a> / </p>
        <p><a class="contents" href="#">CONTACT</a> / </p>
        <p><a class="contents" href="#">PHOTOGRAPHY</a></p>

      </div>
    </div>
  </div>

</section>


<section id="about">  <!-------------------------  ABOUT PAGE  -------------------------->


  <div class="container">
    <div class="row about">
      <div class="col-md-6">
        <p class="big-text"></p>
      </div>
    </div>

    <div class="row">
      <div class="col-md-6 about-text">
        <p >Yup</p>
      </div>
    </div>
  </div>
</section> 

Answer 1

change #header height to min-height:

#header { 
    min-height: 100%; 
}

Answer 2

You can use css vh property for this.

#header {
    height: 100vh;
}

here is more info about css units. Hope this helps you.