title: How does hexadecimal color work?
body: <p>What does the hexadecimal that represents a CSS color mean? How can I tell what color it is without memorizing the exact code? Does it have any relationships with RGB (and CMYK) system?<br>
  I thought for a moment that <code>FF</code> means <code>255</code> in RGB, but then I realized that 15^2 isn't 255, but 225.</p>