/* https://grabient.com/_gCHf6Ef9wgEqgRNgMfgDegBngBogKegM1gMX?style=linearGradient&steps=5&angle=270 */

background: linear-gradient(270deg, #00180f 0.000%, #173f2f 25.000%, #31624c 50.000%, #4a8066 75.000%, #5e987c 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gCHf6Ef9wgEqgRNgMfgDegBngBogKegM1gMX?style=linearGradient&steps=5&angle=270 -->
            <defs>
              <linearGradient id="gradient" x1="1.000" y1="0.500" x2="0.000" y2="0.500">
        <stop offset="0.000" stop-color="#00180f" /><stop offset="0.250" stop-color="#173f2f" /><stop offset="0.500" stop-color="#31624c" /><stop offset="0.750" stop-color="#4a8066" /><stop offset="1.000" stop-color="#5e987c" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#00180f", "#173f2f", "#31624c", "#4a8066", "#5e987c"]

// https://grabient.com/_gCHf6Ef9wgEqgRNgMfgDegBngBogKegM1gMX?style=linearGradient&steps=5&angle=270
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 5.0;
const float ANGLE = 270.0;

vec3 palette(float t) {
    vec3 a = vec3(0.135, -0.380, -0.144);
    vec3 b = vec3(0.298, 1.101, 0.799);
    vec3 c = vec3(0.222, 0.103, 0.104);
    vec3 d = vec3(0.670, 0.821, 0.791);
    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);
}

[
  [0.135, -0.380, -0.144],
  [0.298, 1.101, 0.799],
  [0.222, 0.103, 0.104],
  [0.670, 0.821, 0.791]
]

Gradient palette editor — #00180f to #5e987c