title: How to add/subtract Hue, Brigtness or Saturation of a hexadecimal RGB color, using SASS?
body: <p>By example, I have a color #3e779d. If I subtract 5 of brightness, I get #396d8f.</p>
  
  <p>I search a method in pure SASS (with function?), not SASS extension (as <a href="https://gist.github.com/1932866" rel="nofollow">https://gist.github.com/1932866</a>).</p>
  
  <p>It's possible?</p>
  
  <p>Thanks!</p>