Inspect RebeccaPurple (#663399) in HEX, RGB, HSL, LCH and OKLCH, check its contrast, and copy the value you need.
RebeccaPurple
#663399
White text reads best on this background, at 8.41:1.
RebeccaPurple is one of the 148 CSS named colors, and resolves to #663399 in every browser. In numbers that is rgb(102, 51, 153) and hsl(270, 50%, 40%). Perceptually it is a dark, moderately saturated color: OKLCH puts its lightness at 44% and its chroma at 0.16. It sits in the purples at 303 degrees of OKLCH hue, and reads as a cool color.
White text clears WCAG AA on a RebeccaPurple background at 8.41:1, and AAA as well. That combination of lightness and chroma makes it a workable mid-tone, the kind of value that lands in the middle of a shade scale.
The closest CSS named colors to RebeccaPurple, measured with CIEDE2000, are DarkSlateBlue (#483D8B), DarkMagenta (#8B008B), Purple (#800080). If RebeccaPurple is not quite right, those are the nearest keywords to try before reaching for a custom value.
HEX
#663399
RGB
rgb(102, 51, 153)
HSL
hsl(270, 50%, 40%)
HWB
hwb(270 20% 40%)
CMYK
cmyk(33%, 67%, 0%, 40%)
LAB
lab(32.39 38.42 -47.69)
LCH
lch(32.39 61.24 308.86)
OKLCH
oklch(44.03% 0.1603 303.37)
WCAG asks for 4.5:1 between body text and its background. On #663399 white text measures 8.41:1 and black text 2.5:1, so white clears it and black does not.
White text on RebeccaPurple
WCAG 2.2
8.41:1
APCA
Lc 93
Passes AA body text
Passes AAA body text
Passes AA large text
Black text on RebeccaPurple
WCAG 2.2
2.5:1
APCA
Lc 15
Fails AA body text
Fails AAA body text
Fails AA large text
Check RebeccaPurple against any other color in the contrast checker.
RebeccaPurple sits at 44% OKLCH lightness. Holding its hue and chroma and moving only that value carries it up to #FAF7FF and down to #0B0019, which keeps the family recognizable instead of letting it drift toward gray the way a plain HSL ramp does.
#8554BC
20% lighter
#A675E0
40% lighter
#C699FF
60% lighter
#DFC9FF
80% lighter
#FAF7FF
100% lighter
#541E85
20% darker
#430371
40% darker
#2F0052
60% darker
#1C0034
80% darker
#0B0019
100% darker
Build a full accessible scale from #663399 in the shade generator.
Hues rotated around #663399 in OKLCH, then pulled back into the sRGB gamut. Each swatch is labelled with the nearest CSS named color so you have a keyword to start from.
RebeccaPurple sits at 303 degrees. Rotating it a half turn lands on 123 degrees, the hue directly opposite. It is the strongest pairing you can make without changing lightness, and the one most likely to vibrate if you use both at full chroma.
The neighbors of RebeccaPurple at 273 and 333 degrees. They stay close enough to read as the same family, which is what you want for hover states, secondary surfaces and gradients.
303, 63 and 183 degrees divide the wheel into thirds. Balanced enough to carry a whole palette without one color dominating the other two.
Instead of the complement at 123 degrees, this pair flanks it at 93 and 153. You keep most of the contrast of a complementary pairing while losing the harshness.
Explore more combinations around RebeccaPurple on the color wheel.
The biggest shift is under achromatopsia, where #663399 reads as #454545, 26.5 CIEDE2000 units away. If RebeccaPurple is the only thing marking a state or a series, roughly one viewer in twelve will miss it.
Protanopia
#26439E
Deuteranopia
#2E4695
Tritanopia
#613E52
Achromatopsia
#454545
The nearest CSS keywords to #663399, ranked by perceptual distance rather than by how close their hex digits happen to look.