Almost black to indigo blue to barney purple gradient palette editor

/* https://grabient.com/_gIkepCgIigH_hmjgHWgE4gBjgLbfjvgKsgC6gAtivokz?style=linearGradient&steps=6&angle=90 */

background: linear-gradient(90deg, #1b1c24 0.000%, #231b49 20.000%, #3b03a2 40.000%, #5f00ea 60.000%, #8a00e7 80.000%, #b5009c 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gIkepCgIigH_hmjgHWgE4gBjgLbfjvgKsgC6gAtivokz?style=linearGradient&steps=6&angle=90 -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#1b1c24" /><stop offset="0.200" stop-color="#231b49" /><stop offset="0.400" stop-color="#3b03a2" /><stop offset="0.600" stop-color="#5f00ea" /><stop offset="0.800" stop-color="#8a00e7" /><stop offset="1.000" stop-color="#b5009c" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#1b1c24", "#231b49", "#3b03a2", "#5f00ea", "#8a00e7", "#b5009c"]

// https://grabient.com/_gIkepCgIigH_hmjgHWgE4gBjgLbfjvgKsgC6gAtivokz?style=linearGradient&steps=6&angle=90
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 6.0;
const float ANGLE = 90.0;

vec3 palette(float t) {
    vec3 a = vec3(0.548, -5.566, 0.546);
    vec3 b = vec3(0.443, 5.684, 0.407);
    vec3 c = vec3(0.312, 0.099, 0.731);
    vec3 d = vec3(-1.502, 0.991, 0.493);
    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);
}

[
  [0.548, -5.566, 0.546],
  [0.443, 5.684, 0.407],
  [0.312, 0.099, 0.731],
  [-1.502, 0.991, 0.493]
]