title: Transform property extends webpage, also having center issues
body: <p>Here's the codepen if it's easier. I'm also a beginner, just a heads up.</p>
  
  <p><a href="http://codepen.io/anon/pen/yaRpPL" rel="nofollow">http://codepen.io/anon/pen/yaRpPL</a></p>
  
  <p>My problem is that every time I hover over this circle, it extends the page size large enough that a scroll bar comes up when the circle reaches max size. I don't know how to explain, I just don't want that to happen...</p>
  
  <p>Also, I can't get the text in the center of that circle to appear <em>directly</em> in the center. I feel like I've tried every CSS property I could think of.</p>
  
  <p>Lastly, any tips on getting that circle to stay in the center for most common screen resolutions would be greatly appreciated. I have the margins set to percentages and it seems to be okay.</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  
  &lt;html&gt;
      &lt;head&gt;
          &lt;meta charset="UTF-8"&gt;
          &lt;title&gt;Echoes from Firelink&lt;/title&gt;
          &lt;link href="homepage.css" type="text/css" rel="stylesheet"&gt;
          &lt;link rel="shortcut icon" href="coiledsword.ico"&gt;
      &lt;/head&gt;
  
      &lt;header&gt;
                  &lt;a href="homepage.htm" style="color:black"&gt;home | &lt;/a&gt;
                  &lt;a href="homepage_easy.htm" style="color:black"&gt;lite version&lt;/a&gt;
              &lt;/header&gt;&lt;!--End header--&gt;
      &lt;body&gt;
          &lt;div id="background_container"&gt;
              &lt;div id="content_container"&gt;
              &lt;p&gt;From Software homepage&lt;/p&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>CSS:</p>
  
  <pre><code>/* CSS page for the homepage. */
  
  header {
      text-align: center;
      font-size: 10px;
  }
  #content_container {
      background-color: black;
      text-align:center;
      color: white;
      height: 200px;
      width: 200px;
      margin: 20% 45% 20% 45%;
      border-radius: 50%;
      transition: 2s;
  }
  
  #content_container:hover {
      transform: scale(1.4);
  }
  </code></pre>