Black Box as a scale
Eleven steps from #0f282f, built by moving lightness in OKLCh and keeping the hue where it is. Every step is gamut-mapped by giving up chroma, never by clipping channels — clipping is what turns a light blue purple.
| Stop | Hex | OKLCh L | Chroma | On white | On black | APCA on white | ΔE00 from the step above |
|---|---|---|---|---|---|---|---|
| 50 | #e6f9ff | 97.0% | 0.021 ·capped | 1.08:1 | 19.36:1 | 0 | — |
| 100 | #d3f0fa | 93.8% | 0.033 | 1.19:1 | 17.66:1 | 9 | 4.0 |
| 200 | #bedbe4 | 87.4% | 0.033 | 1.45:1 | 14.49:1 | 21 | 4.7 |
| 300 | #aac7d0 | 81.0% | 0.033 | 1.79:1 | 11.75:1 | 33 | 5.0 |
| 400 | #96b2bb | 74.6% | 0.033 | 2.23:1 | 9.40:1 | 44 | 5.5 |
| 500 | #839ea7 | 68.2% | 0.033 | 2.83:1 | 7.43:1 | 54 | 6.0 |
| 600 | #708b93 | 61.8% | 0.033 | 3.63:1 | 5.79:1 | 64 | 6.6 |
| 700 | #5d7880 | 55.4% | 0.033 | 4.71:1 | 4.46:1 | 73 | 7.3 |
| 800 | #4b656d | 49.0% | 0.033 | 6.18:1 | 3.40:1 | 81 | 7.0 |
| 900 | #233c44 | 34.0% | 0.033 | 11.63:1 | 1.81:1 | 97 | 13.9 |
| 950 | #00151b | 18.0% | 0.032 ·capped | 18.72:1 | 1.12:1 | 105 | 12.3 |
What is true of this ramp
- 10 of the 10 adjacent pairs differ by ΔE00 2 or more. Every step here is a step a reader can see.
- The tightest pair is 50 to100, at ΔE00 4.0.
- 2 steps had to give up chroma to stay inside sRGB — 50, 950. A wider display would show them more vividly.
- 4 steps clear 4.5:1 on white (700, 800, 900, 950), and 7 on black (50, 100, 200, 300, 400, 500, 600).
Harmonies from Black Box
complement
the hue directly opposite, at the same lightness. #321e18 (+180°)
analogous
the two neighbours 30° either side. #0e2927 (+-30°), #172534 (+30°)
split complement
the two hues either side of the opposite, 30° apart from it. #321d21 (+150°), #2f2112 (+210°)
triad
the circle divided in three. #2f1e2a (+120°), #282411 (+240°)
tetrad
the circle divided in four. #292031 (+90°), #321e18 (+180°), #1f2716 (+270°)
The ramp as CSS
:root {
--black-box-50: #e6f9ff;
--black-box-100: #d3f0fa;
--black-box-200: #bedbe4;
--black-box-300: #aac7d0;
--black-box-400: #96b2bb;
--black-box-500: #839ea7;
--black-box-600: #708b93;
--black-box-700: #5d7880;
--black-box-800: #4b656d;
--black-box-900: #233c44;
--black-box-950: #00151b;
}