Muted monochrome gainsboro to deep aqua gradient palette editor

/* https://grabient.com/_gJwf3SgK_gF8gWwgGagEVgBjgCxgCQgAegCv */

background: linear-gradient(90deg, #dbdee3 0.000%, #c3d5d1 16.667%, #a7c8be 33.333%, #8bb8aa 50.000%, #71a397 66.667%, #5b8c85 83.333%, #4a7275 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gJwf3SgK_gF8gWwgGagEVgBjgCxgCQgAegCv -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#dbdee3" /><stop offset="0.167" stop-color="#c3d5d1" /><stop offset="0.333" stop-color="#a7c8be" /><stop offset="0.500" stop-color="#8bb8aa" /><stop offset="0.667" stop-color="#71a397" /><stop offset="0.833" stop-color="#5b8c85" /><stop offset="1.000" stop-color="#4a7275" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#dbdee3", "#c3d5d1", "#a7c8be", "#8bb8aa", "#71a397", "#5b8c85", "#4a7275"]

// https://grabient.com/_gJwf3SgK_gF8gWwgGagEVgBjgCxgCQgAegCv
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 7.0;
const float ANGLE = 90.0;

vec3 palette(float t) {
    vec3 a = vec3(0.624, -0.558, 0.703);
    vec3 b = vec3(0.380, 1.456, 0.410);
    vec3 c = vec3(0.277, 0.099, 0.177);
    vec3 d = vec3(0.144, 0.030, 0.175);
    return a + b * cos(6.283185 * (c * t + d));
}

// N stops sampled from the palette, blended like the CSS gradient
vec3 stops(float t) {
    float n = STEPS - 1.0;
    float x = clamp(t, 0.0, 1.0) * n;
    return mix(palette(floor(x) / n), palette(min(floor(x) + 1.0, n) / n), fract(x));
}

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 p = fragCoord - 0.5 * iResolution.xy;
    // CSS angle: 0 = up, clockwise; span = CSS gradient-line length
    vec2 dir = vec2(sin(radians(ANGLE)), cos(radians(ANGLE)));
    float len = abs(iResolution.x * dir.x) + abs(iResolution.y * dir.y);
    float t = dot(p, dir) / len + 0.5;
    fragColor = vec4(stops(t), 1.0);
}

[
  [0.624, -0.558, 0.703],
  [0.380, 1.456, 0.410],
  [0.277, 0.099, 0.177],
  [0.144, 0.030, 0.175]
]