#0A0A0A
#3D3D3D
#CCFF00
#FFFFFF
#3D3D3D is a dark, nearly neutral gray color, closest to Iron and near Iron and Onyx. In OKLCH it has 36% lightness and 0.00 chroma at hue 0°. Gray suggests neutrality and balance; it lets other colors lead, which makes #3D3D3D a natural choice for text, borders and interface chrome. It appears in 2 ColorSwoop palettes.
#3D3D3Drgb(61, 61, 61)hsl(0, 0%, 24%)0, 0, 0, 76--iron10.86:1 white · 1.93:1 blackWhite text passes WCAG AA on #3D3D3D (10.86:1); black does not, so keep dark text off it.
For a calm scheme pair #3D3D3D with its analogous neighbors #3D3D3D and #3D3D3D; for contrast use its complement #3D3D3D as a small accent, and anchor everything with a neutral such as #F5F5F7.
--iron: #3D3D3D;
$iron: #3D3D3D;
colors: { 'iron': '#3D3D3D' }