I design in the CSS and always stick to shades of gray until I get the layout and interactions right, which are easy to reason and conjure off the top of my head. I can always tell `#ccc` is lighter than `#cacaca` but it's not easy tell how luminant a color is just by looking at its hex.

Lately, I've been playing with HSL, which makes the calculations easier, but luminescence is still difficult. Hopefully, LAB color space will be useful in that regard.