title: Show unchecked checkbox(s) with a different color in mailto
body: <p>I'm doing a form that is supposed to send its answers to an email.
  It does send the checked answers, but i would like to have the unchecked answers in red for example in order to show what's checked and what's not in the mail.</p>
  
  <pre><code>&lt;form action="mailto:myadress@gmail.com?subject=New mail" name="email" method=POST enctype="text/plain"&gt;
  &lt;input type="checkbox" id="check1" name="check1" value="Check_1"&gt;
  &lt;label for="coding"&gt;Check 1&lt;/label&gt;
  &lt;br/&gt;
  &lt;input type="checkbox" id="check2" name="check2" value="Check_2"&gt;
  &lt;label for="coding"&gt;Check 2&lt;/label&gt;
  &lt;br/&gt;
  &lt;input type="checkbox" id="check3" name="check3" value="Check_3"&gt;
  &lt;label for="coding"&gt;Check 3&lt;/label&gt;
  &lt;br /&gt;
  &lt;input type="submit" value="Send"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>If someones could help me with this problem, </p>
  
  <p>Thank you </p>
  
  <p>For example, the mail would be</p>
  
  <p>check1=Check_1</p>
  
  <p><strong>check2=Check_2</strong></p>
  
  <p><strong>check3=Check_3</strong></p>
  
  <p>with red font instead of black</p>