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      <base href="https://bugs.webkit.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - The heights of SVG elements using relative sizes are miscalculated within border-box parents"
   href="https://bugs.webkit.org/show_bug.cgi?id=154049">154049</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>The heights of SVG elements using relative sizes are miscalculated within border-box parents
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>WebKit Nightly Build
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>SVG
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>anthony.lalande&#64;gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>zimmermann&#64;kde.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Overview:
When including an SVG element within a parent element that uses `box-sizing: border-box`, the relative height of the SVG element seems to be miscalculated.


Steps to reproduce:
- Create an enclosing block element with the `box-sizing: border-box` directive.
- Add a padding value &gt; 0 for this enclosing element.
- Create an inner SVG element with the `height: 100%` directive.
- Observe that the SVG element has a height that is too short by a factor of 2x the parent's padding.



Expected results:

I would expect an SVG element to be sized identically to a `&lt;div&gt;` element that uses `box-sizing: border-box`, as here:
<a href="https://jsfiddle.net/p9ke6bo9/">https://jsfiddle.net/p9ke6bo9/</a>

Note that the underlying black box forms a 10px &quot;border&quot; all around the white box.


Actual results:

When you change the `&lt;div&gt;` element to `&lt;svg&gt;` in the example above, the black outline grows to 30px at the bottom:
<a href="https://jsfiddle.net/p9ke6bo9/1/">https://jsfiddle.net/p9ke6bo9/1/</a>

This seems to be because the `&lt;svg&gt;` element is subtracting 4 * 10px (instead of 2 * 10px) from the parent element's height.


Additional example:

When you remove the `box-sizing: border-box` directive from the outer element, the inner `&lt;svg&gt;` element draws correctly:
<a href="https://jsfiddle.net/p9ke6bo9/3/">https://jsfiddle.net/p9ke6bo9/3/</a></pre>
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