Complementary dark red and blue green gradient palette editor

/* https://grabient.com/_gFCgFFgDngLPgLPgGggBlgBogBlgDDgKpgLC?style=linearGradient&steps=5&angle=225 */

background: linear-gradient(225deg, #90061e 0.000%, #74222e 25.000%, #573f3f 50.000%, #3a5d50 75.000%, #1e7b60 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gFCgFFgDngLPgLPgGggBlgBogBlgDDgKpgLC?style=linearGradient&steps=5&angle=225 -->
            <defs>
              <linearGradient id="gradient" x1="0.854" y1="0.146" x2="0.146" y2="0.854">
        <stop offset="0.000" stop-color="#90061e" /><stop offset="0.250" stop-color="#74222e" /><stop offset="0.500" stop-color="#573f3f" /><stop offset="0.750" stop-color="#3a5d50" /><stop offset="1.000" stop-color="#1e7b60" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#90061e", "#74222e", "#573f3f", "#3a5d50", "#1e7b60"]

// https://grabient.com/_gFCgFFgDngLPgLPgGggBlgBogBlgDDgKpgLC?style=linearGradient&steps=5&angle=225
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 5.0;
const float ANGLE = 225.0;

vec3 palette(float t) {
    vec3 a = vec3(0.322, 0.325, 0.231);
    vec3 b = vec3(0.719, 0.719, 0.416);
    vec3 c = vec3(0.101, 0.104, 0.101);
    vec3 d = vec3(0.195, 0.681, 0.706);
    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);
}

[
  [0.322, 0.325, 0.231],
  [0.719, 0.719, 0.416],
  [0.101, 0.104, 0.101],
  [0.195, 0.681, 0.706]
]