title: Is there a reason to use uppercase letters for hexadecimal CSS color values?
body: <p>I see that colors in CSS properties values are commonly written in the uppercase form:</p>
  <pre><code>.foo .bar {
    background-color: #A41B35;
    color: #FFF;
  }
  </code></pre>
  <p>But you can also use:</p>
  <pre><code>/* Same same */
  .foo .bar {
    background-color: #a41b35;
    color: #fff;
  }
  </code></pre>
  <p>Or <a href="https://en.wikipedia.org/wiki/Hexadecimal#Representation" rel="noreferrer">even the very controversial</a>:</p>
  <pre><code>/* Check the link to see why it can be interesting */
  .foo .bar {
    background-color: #A41b35;
    color: #FfF;
  }
  </code></pre>
  <p>In any case (ho ho ho), using named colors like <code>white</code>, when possible, in place of <code>#fff</code> kind of make our life easier, but this is another question.</p>
  <p>It looks like using lowercase values does the same, and, CSS values for colors <a href="https://stackoverflow.com/questions/17967371/are-property-values-in-css-case-sensitive">are not case-sensitive</a>. Lots of graphic design software also use the uppercase form. And it is very common to find uppercase notations in source code, it looks like there is something like a tradition.</p>
  <p>I understand about the consistency thing, that it should be the same everywhere in you software, but as the standard doesn't give a good indication, people do <em>what they want</em> or <em>what they are told to do</em>.</p>
  <p>Is there rational reasons for this, like <strong>historic</strong>, compatibility, old IE6 hacks, performances or practical reasons?</p>