title: How would I get the height of my header?
body: <p>So I have a fixed header that DOESN'T have a height specified. It just resizes however it wants according to screen size. But, its fixed so the form below it needs a margin-top so it doesn't sit in front behind it and over it. Would I need to specify a size for the header?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>html,
  body {
    padding: 0;
    margin: 0 auto;
    text-align: center;
    background-color: #ffffff;
    width: 100%;
  }
  
  header {
    /*background-color: white;*/
    top: 0;
    position: fixed;
    width: 100%;
    padding-bottom: 1%;
    padding-top: 1%;
    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
    z-index: 1;
  }
  
  form {
    padding: 0;
    margin: 0;
    /*margin-top: 10%;*/
    text-align: center;
    display: inline-block;
    background-color: red;
  }
  
  form input {
    margin: 0;
    text-align: center;
    appearance: none;
    outline: none;
    border: 1px solid red;
    border-radius: 3px;
    box-sizing: border-box;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;header&gt;
    &lt;nav&gt;
      &lt;ul&gt;
        &lt;li&gt;&lt;a href="includes/php/done.php"&gt;done&lt;/a&gt;&lt;/li&gt;
      &lt;/ul&gt;
    &lt;/nav&gt;
  &lt;/header&gt;
  
  &lt;form class="login"&gt;
    &lt;input type="text" name="username" placeholder="Username"&gt;
    &lt;input type="password" name="password" placeholder="Password"&gt;
    &lt;input id="loginbtn" type="button" name="submit" value="login"&gt;
  &lt;/form&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>You can see the commented code(2 lines) and you'll kinda see what I mean.</p>