#AA0000Heartbeat (#AA0000) is a dark, saturated red with an OKLCH hue of 29°, lightness 0.46 and chroma 0.19. It sits on the warm side of the color wheel. In practice it behaves as an accent color: strong in focal moments, dominant over large fields.
| HEX | #AA0000 |
|---|---|
| RGB | rgb(170, 0, 0) |
| HSL | hsl(0, 100%, 33%) |
| HSV | hsv(0, 100%, 67%) |
| CMYK | cmyk(0%, 100%, 100%, 33%) |
| CIE Lab | lab(35.1 59.1 49.4) |
| OKLCH | oklch(0.463 0.190 29) |
Under warm 2700K interior light Heartbeat is virtually unchanged; in north-facing or shaded light it is virtually unchanged. Overall drift across common illuminants is small (max ΔE ≈ 0.7), so it is a lighting-stable choice.
#aa0000 — ΔE 0.0, is virtually unchanged#ad0000 — ΔE 0.7, is virtually unchanged#aa0000 — ΔE 0.0, is virtually unchanged#ab0101 — ΔE 0.2, is virtually unchangedTest Heartbeat in the color lighting simulator — sweep it through daylight, warm 2700K light, 4000K LED, and shade alongside the rest of your palette.
Against white it measures 7.75:1 and against black 2.71:1, so white text is the stronger pairing. That pairing passes WCAG AA for body text. Avoid black text on this color entirely.
One color explored: close hues with real lightness and chroma structure, so the palette is the anchor through value rather than a set of colors.
#f98676 · #d75748 · #aa0000 · #7e0000 · #470000 · #180000
The anchor's neighbours on the wheel — everything shares an undertone, so the chord carries color without anything having to be muted to get along.
#b36500 · #ac4600 · #aa0000 · #8a002e · #6b0039 · #4e003b
The mid-gap pairing — sage and mustard, terracotta and olive. A foil rotated 40–65° toward warm or cool: too far to be kin, too near to argue, carried by temperature and a deliberate value offset.
#d4ab61 · #bd8900 · #926f2b · #aa0000 · #7a0000 · #4e0000
One deliberately opposed voice — a single restrained counterpoint across the wheel, or temperature against temperature where the anchor is too muted to carry a loud opposite.
#00dcf5 · #cd8377 · #976c65 · #aa0000 · #671f18 · #3a110c
The anchor as the only color in the room. True neutrals or complement-warmed near-neutrals let it stay dominant.
#def7fc · #c7a8a2 · #657679 · #aa0000 · #563733 · #000304
This color as a ground rather than a subject — its own restraint held across a narrow value band, carrying one saturated voice from the opposite temperature.
#e6f5f7 · #bccdd0 · #8ea1a5 · #0f2a2e · #00070a · #aa0000
The opposite hue on the perceptual wheel, tempered to field strength — warm/cool tension without vibration.
#d7f9ff · #00c6dd · #008191 · #aa0000 · #004a53 · #080000
The complement's two neighbours instead of the complement itself — strong contrast with a lower clash risk.
#cfd7b2 · #76b3db · #589086 · #aa0000 · #3f4d3d · #190c03
Three hues spaced evenly around the wheel; the anchor leads and the other two are held at supporting strength.
#d8fddd · #60ca79 · #4765e0 · #aa0000 · #213294 · #000200
Two complementary pairs offset by 90° — the richest chord, kept usable by a strict lightness hierarchy.
#edf8cd · #a6bd3e · #008191 · #aa0000 · #4f1f88 · #000304
#BF3E31 · #D36354 · #E68577 · #F7A699 · #FFCBC2
#8F0000 · #750000 · #5C0000 · #440000 · #2E0000
#9B2B21 · #8C3D33 · #7B4A42
Its chroma is high enough to carry accents, calls to action, and focal moments; large fields of it will dominate a composition. In palettes it pairs most predictably with its tonal ramp and analogous neighbors; reserve the complementary hue for small, deliberate contrast.