/* https://grabient.com/_gI1gH0gphgHlgGvglqgHEgGqgBjgHLgJCgHr?style=linearGradient&steps=6&angle=225 */

background: linear-gradient(225deg, #181f40 0.000%, #1a4640 20.000%, #417e4a 40.000%, #81b75e 60.000%, #c5df7a 80.000%, #f9ed9f 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gI1gH0gphgHlgGvglqgHEgGqgBjgHLgJCgHr?style=linearGradient&steps=6&angle=225 -->
            <defs>
              <linearGradient id="gradient" x1="0.854" y1="0.146" x2="0.146" y2="0.854">
        <stop offset="0.000" stop-color="#181f40" /><stop offset="0.200" stop-color="#1a4640" /><stop offset="0.400" stop-color="#417e4a" /><stop offset="0.600" stop-color="#81b75e" /><stop offset="0.800" stop-color="#c5df7a" /><stop offset="1.000" stop-color="#f9ed9f" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#181f40", "#1a4640", "#417e4a", "#81b75e", "#c5df7a", "#f9ed9f"]

// https://grabient.com/_gI1gH0gphgHlgGvglqgHEgGqgBjgHLgJCgHr?style=linearGradient&steps=6&angle=225
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 6.0;
const float ANGLE = 225.0;

vec3 palette(float t) {
    vec3 a = vec3(0.565, 0.500, 2.657);
    vec3 b = vec3(0.485, 0.431, 2.410);
    vec3 c = vec3(0.452, 0.426, 0.099);
    vec3 d = vec3(0.459, 0.578, 0.491);
    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);
}

[
  [0.565, 0.500, 2.657],
  [0.485, 0.431, 2.410],
  [0.452, 0.426, 0.099],
  [0.459, 0.578, 0.491]
]

Gradient palette editor — #181f40 to #f9ed9f