/* https://grabient.com/_f-GgKSgFLgIRgBsgCIgBngQOgJQgAdgHLgMU?style=linearGradient&steps=6&angle=180 */

background: linear-gradient(180deg, #668d5d 0.000%, #619a71 20.000%, #5bbb77 40.000%, #52c06a 60.000%, #48a152 80.000%, #3c8c3b 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_f-GgKSgFLgIRgBsgCIgBngQOgJQgAdgHLgMU?style=linearGradient&steps=6&angle=180 -->
            <defs>
              <linearGradient id="gradient" x1="0.500" y1="0.000" x2="0.500" y2="1.000">
        <stop offset="0.000" stop-color="#668d5d" /><stop offset="0.200" stop-color="#619a71" /><stop offset="0.400" stop-color="#5bbb77" /><stop offset="0.600" stop-color="#52c06a" /><stop offset="0.800" stop-color="#48a152" /><stop offset="1.000" stop-color="#3c8c3b" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#668d5d", "#619a71", "#5bbb77", "#52c06a", "#48a152", "#3c8c3b"]

// https://grabient.com/_f-GgKSgFLgIRgBsgCIgBngQOgJQgAdgHLgMU?style=linearGradient&steps=6&angle=180
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 6.0;
const float ANGLE = 180.0;

vec3 palette(float t) {
    vec3 a = vec3(-0.122, 0.658, 0.331);
    vec3 b = vec3(0.529, 0.108, 0.136);
    vec3 c = vec3(0.103, 1.038, 0.592);
    vec3 d = vec3(0.029, 0.459, 0.788);
    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);
}

[
  [-0.122, 0.658, 0.331],
  [0.529, 0.108, 0.136],
  [0.103, 1.038, 0.592],
  [0.029, 0.459, 0.788]
]

Gradient palette editor — #668d5d to #3c8c3b