Sure Boom Moss
Sure Boom Moss (#639138) is a true lime with an earthy character. It leans grounded and natural, the kind of color that plays well with wood, clay, linen, and warm neutrals. Its HSL profile (91°, 44%, 39%) places it in the balanced band at a mid lightness. It works across type, buttons, and borders, saturated enough to feel deliberate but balanced enough to not fight the rest of the palette. For a confident two-color system, pair it with its complementary indigo. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Old French seur, certain — used as a color modifier since the medieval period for hues that read as confident and stable. Sure red, sure blue: moderate saturation combined with optical commitment. Sits at the crisp-bucket center alongside steady and true.
Dutch boom, tree / spar. As a color modifier, boom implies a horizontal-spar-attached-to-mast quality, the visual register of Tall-Ship-and-yacht-boom hand-cut horizontal-spar-attached-to-mast-foot boom-and-mainsail tall-ship-and-yacht maritime-rigging surfaces under tall-ship-and-yacht boom-and-mainsail maritime light. Sits at the modifier-and-nautical end of the grid, parallel to spar and mast in usage.
Bryophyta — the nonvascular plants that colonized land 470 million years ago, before vascular plants and far before flowers. The color refers to a thick mat of Hypnum or sphagnum on a temperate forest floor: a soft, slightly yellow-shifted green with the velvet texture of millimeter-scale leaves. Dustier than fern, deeper than lichen, with the slow patience of a plant that lives by absorbing rain through its surface.
Closest matches
The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.
Variations
Click any swatch to exploreHarmonies
Accessibility
How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.
The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.
Wide gamut
The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.
Moderately saturated colors gain a small bump in P3 — the difference is usually visible side-by-side on wide-gamut hardware but won't change the character of the color.