Inspect SlateGrey (#708090) in HEX, RGB, HSL, LCH and OKLCH, check its contrast, and copy the value you need.
SlateGrey
#708090
Black text reads best on this background, at 5.18:1.
SlateGrey is one of the 148 CSS named colors, and resolves to #708090 in every browser. In numbers that is rgb(112, 128, 144) and hsl(210, 13%, 50%). Perceptually it is a mid-toned, near-neutral color: OKLCH puts its lightness at 59% and its chroma at 0.031. It carries almost no chroma, so it behaves as a neutral rather than as a hue, and belongs with the grays.
White text only reaches 4.05:1 here, so black text is the safer pairing at 5.18:1. With this little chroma it recedes, which makes it useful for borders, dividers and secondary surfaces.
The closest CSS named colors to SlateGrey, measured with CIEDE2000, are LightSlateGray (#778899), LightSlateGrey (#778899), Gray (#808080). If SlateGrey is not quite right, those are the nearest keywords to try before reaching for a custom value.
HEX
#708090
RGB
rgb(112, 128, 144)
HSL
hsl(210, 13%, 50%)
HWB
hwb(210 44% 44%)
CMYK
cmyk(22%, 11%, 0%, 44%)
LAB
lab(52.7 -3.28 -10.74)
LCH
lch(52.7 11.23 253)
OKLCH
oklch(59.25% 0.0309 248.35)
WCAG asks for 4.5:1 between body text and its background. On #708090 white text measures 4.05:1 and black text 5.18:1, so black clears it and white does not.
White text on SlateGrey
WCAG 2.2
4.05:1
APCA
Lc 73
Fails AA body text
Fails AAA body text
Passes AA large text
Black text on SlateGrey
WCAG 2.2
5.18:1
APCA
Lc 36
Passes AA body text
Fails AAA body text
Passes AA large text
Check SlateGrey against any other color in the contrast checker.
SlateGrey sits at 59% OKLCH lightness. Holding its hue and chroma and moving only that value carries it up to #F3F9FF and down to #000611, which keeps the family recognizable instead of letting it drift toward gray the way a plain HSL ramp does.
#8797A8
20% lighter
#9EAFC0
40% lighter
#B7C8D9
60% lighter
#CFE1F3
80% lighter
#F3F9FF
100% lighter
#556574
20% darker
#3C4A59
40% darker
#24323F
60% darker
#0D1A27
80% darker
#000611
100% darker
Build a full accessible scale from #708090 in the shade generator.
Hues rotated around #708090 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.
SlateGrey sits at 248 degrees. Rotating it a half turn lands on 68 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 SlateGrey at 218 and 278 degrees. They stay close enough to read as the same family, which is what you want for hover states, secondary surfaces and gradients.
248, 8 and 128 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 68 degrees, this pair flanks it at 38 and 98. You keep most of the contrast of a complementary pairing while losing the harshness.
Explore more combinations around SlateGrey on the color wheel.
The biggest shift is under tritanopia, where #708090 reads as #698485, 9.8 CIEDE2000 units away. If SlateGrey is the only thing marking a state or a series, roughly one viewer in twelve will miss it.
Protanopia
#7A8091
Deuteranopia
#767C90
Tritanopia
#698485
Achromatopsia
#7E7E7E
The nearest CSS keywords to #708090, ranked by perceptual distance rather than by how close their hex digits happen to look.