Dark marine to metallic blue to grape purple gradient palette editor

/* https://grabient.com/_gDmgEegDYgCigCMgE1gMSgQUgHxgGugIigLy */

background: linear-gradient(90deg, #152739 0.000%, #144260 16.667%, #2c657c 33.333%, #4d6986 50.000%, #624b7b 66.667%, #5e2a5e 83.333%, #432b37 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gDmgEegDYgCigCMgE1gMSgQUgHxgGugIigLy -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#152739" /><stop offset="0.167" stop-color="#144260" /><stop offset="0.333" stop-color="#2c657c" /><stop offset="0.500" stop-color="#4d6986" /><stop offset="0.667" stop-color="#624b7b" /><stop offset="0.833" stop-color="#5e2a5e" /><stop offset="1.000" stop-color="#432b37" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#152739", "#144260", "#2c657c", "#4d6986", "#624b7b", "#5e2a5e", "#432b37"]

// https://grabient.com/_gDmgEegDYgCigCMgE1gMSgQUgHxgGugIigLy
// 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(0.230, 0.286, 0.216);
    vec3 b = vec3(0.162, 0.140, 0.309);
    vec3 c = vec3(0.786, 1.044, 0.497);
    vec3 d = vec3(0.430, 0.546, 0.754);
    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);
}

[
  [0.230, 0.286, 0.216],
  [0.162, 0.140, 0.309],
  [0.786, 1.044, 0.497],
  [0.430, 0.546, 0.754]
]