A Kind Of Blue

239 (!) different ways to write the same shade of blue using modern CSS.

...what?

OK, here's how it happens:

• Nine different ways to specify a color: named colors, hex codes, rgb(), hsl(), hwb(), lab(), lch(), oklab() and oklch()
• Four different hex codes (#00f, #00ff, #0000ff, #0000ffff)
• RGB values can be decimals (0-255) or percentages (0%-100%)
• Anything with a hue component - so hsl(), hwb(), lab(), lch(), oklab() and oklch()? Hue is an angle. Angles in CSS can be degrees with no unit, degrees, radians, gradians, or turns.
• lab and oklab take axis values which can be decimals or percentages
• Color functions all have two different ways to specify opacity: / 1.0 and / 100%

This is ONLY the modern syntax. Legacy syntax (r,g,b), and aliases rgba() and hsla() also still work, which probably adds another few dozen ways to say "the box is blue" that work in all modern browsers.