Rainbow dark red to midnight blue to dark teal to mud brown gradient palette editor

/* https://grabient.com/_gD8gCKgDagEjgC9gDugMzgNpgThgP6gEzgF_ */

background: linear-gradient(90deg, #8a120b 0.000%, #6a0005 16.667%, #2d004a 33.333%, #002174 50.000%, #004845 66.667%, #2a5202 83.333%, #67380f 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gD8gCKgDagEjgC9gDugMzgNpgThgP6gEzgF_ -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#8a120b" /><stop offset="0.167" stop-color="#6a0005" /><stop offset="0.333" stop-color="#2d004a" /><stop offset="0.500" stop-color="#002174" /><stop offset="0.667" stop-color="#004845" /><stop offset="0.833" stop-color="#2a5202" /><stop offset="1.000" stop-color="#67380f" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#8a120b", "#6a0005", "#2d004a", "#002174", "#004845", "#2a5202", "#67380f"]

// https://grabient.com/_gD8gCKgDagEjgC9gDugMzgNpgThgP6gEzgF_
// 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(0.252, 0.138, 0.218);
    vec3 b = vec3(0.291, 0.189, 0.238);
    vec3 c = vec3(0.819, 0.873, 1.249);
    vec3 d = vec3(1.018, 0.307, 0.383);
    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);
}

[
  [0.252, 0.138, 0.218],
  [0.291, 0.189, 0.238],
  [0.819, 0.873, 1.249],
  [1.018, 0.307, 0.383]
]