/* https://grabient.com/_fpogHSgIAglygHXgHigBjgBigG7gN5gGtgJm */

background: linear-gradient(90deg, #6b0a26 0.000%, #920654 16.667%, #b3028c 33.333%, #ce00c1 50.000%, #e300ea 66.667%, #f200fd 83.333%, #fa00f6 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_fpogHSgIAglygHXgHigBjgBigG7gN5gGtgJm -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#6b0a26" /><stop offset="0.167" stop-color="#920654" /><stop offset="0.333" stop-color="#b3028c" /><stop offset="0.500" stop-color="#ce00c1" /><stop offset="0.667" stop-color="#e300ea" /><stop offset="0.833" stop-color="#f200fd" /><stop offset="1.000" stop-color="#fa00f6" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#6b0a26", "#920654", "#b3028c", "#ce00c1", "#e300ea", "#f200fd", "#fa00f6"]

// https://grabient.com/_fpogHSgIAglygHXgHigBjgBigG7gN5gGtgJm
// 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(-1.432, 0.466, 0.512);
    vec3 b = vec3(2.418, 0.471, 0.482);
    vec3 c = vec3(0.099, 0.098, 0.443);
    vec3 d = vec3(0.889, 0.429, 0.614);
    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);
}

[
  [-1.432, 0.466, 0.512],
  [2.418, 0.471, 0.482],
  [0.099, 0.098, 0.443],
  [0.889, 0.429, 0.614]
]

Gradient palette editor — #6b0a26 to #fa00f6