title: Chrome seems to miscalculate css sizes given in mm unit when printing
body: <p>I want to print to A4 using css.</p>
  
  <p>A4 is 297mm high - 6 mm margin top - 6 mm margin bottom = 285 mm should be left for content.</p>
  
  <p>In IE 11 :
  I have to set page borders to 6 mm and disable header/footer
  --> Text appears where it should when I set content height to 284 mm (1 mm diff is close enough for me)
  <img src="https://i.stack.imgur.com/6CVHb.png" alt="IE 11: OK: Text at 284 mm is located at bottom of page 1"></p>
  
  <p>In Chrome 33:
  I don't have to change any settings
  --> Text is located far below from where it should be. It only works when I set content height to 267 mm (where did 18 mm diff go?)
  <img src="https://i.stack.imgur.com/XE37R.png" alt="Chrome 33: Fail: Text at 284 mm is located somewhere near top of page 2"></p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
     &lt;head&gt;
        &lt;style type="text/css"&gt;
           @page {
              margin: 6mm;
              size: A4 portrait;
           }
           body {
              margin: 0mm;
           }
           table {
              page-break-after: always;
              border-spacing:0mm;
           }
           tr {
              vertical-align: bottom;
              height:284mm;
           }
        &lt;/style&gt;
     &lt;/head&gt;
     &lt;body&gt;
        &lt;table&gt;
           &lt;tr&gt;
              &lt;td&gt;Page 1&lt;/td&gt;
           &lt;/tr&gt;
        &lt;/table&gt;
        &lt;table&gt;
           &lt;tr&gt;
              &lt;td&gt;Page 2&lt;/td&gt;
           &lt;/tr&gt;
       &lt;/table&gt;
     &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Is there something wrong with my css or does Chrome not know the size of 1 mm?</p>