Dark Gray (#a9a9a9) is a light, grayish gray. It is a CSS named color, so you can use it in stylesheets as color: darkgray as well as by its hex code. In RGB it is rgb(169, 169, 169); in HSL, hsl(0, 0%, 66%).
The hue is calculated at seven exact lightness levels for use in backgrounds, borders, text and hover states. These values are not substituted with nearby named colors.
#ebebeb
#c7c7c7
#a3a3a3
#808080
#5c5c5c
#3d3d3d
#242424
Color schemes with #a9a9a9
#a9a9a9 is a neutral: it carries little to no hue, so wheel-based schemes like complementary or triadic would simply return the same gray. Neutrals work differently — use the ramp above for backgrounds, borders and text, and pair #a9a9a9 with a saturated accent for links, buttons and highlights. Each of these accents reads clearly against #a9a9a9:
On a #a9a9a9 background, black text gives the better contrast. WCAG requires 4.5:1 for normal text and 3:1 for large text (AA), or 7:1 and 4.5:1 for AAA.