Monochrome very dark purple to light lilac gradient palette editor

/* https://grabient.com/_gJQgGrgFQgIQgHRgKogEKgEVgFRgJWgJLgLL?style=linearGradient&steps=6&angle=225 */

background: linear-gradient(225deg, #290830 0.000%, #492379 20.000%, #7147bb 40.000%, #9d6fec 60.000%, #c998ff 80.000%, #efbbfa 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gJQgGrgFQgIQgHRgKogEKgEVgFRgJWgJLgLL?style=linearGradient&steps=6&angle=225 -->
            <defs>
              <linearGradient id="gradient" x1="0.854" y1="0.146" x2="0.146" y2="0.854">
        <stop offset="0.000" stop-color="#290830" /><stop offset="0.200" stop-color="#492379" /><stop offset="0.400" stop-color="#7147bb" /><stop offset="0.600" stop-color="#9d6fec" /><stop offset="0.800" stop-color="#c998ff" /><stop offset="1.000" stop-color="#efbbfa" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#290830", "#492379", "#7147bb", "#9d6fec", "#c998ff", "#efbbfa"]

// https://grabient.com/_gJQgGrgFQgIQgHRgKogEKgEVgFRgJWgJLgLL?style=linearGradient&steps=6&angle=225
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 6.0;
const float ANGLE = 225.0;

vec3 palette(float t) {
    vec3 a = vec3(0.592, 0.427, 0.336);
    vec3 b = vec3(0.528, 0.465, 0.680);
    vec3 c = vec3(0.266, 0.277, 0.337);
    vec3 d = vec3(0.598, 0.587, 0.715);
    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);
}

[
  [0.592, 0.427, 0.336],
  [0.528, 0.465, 0.680],
  [0.266, 0.277, 0.337],
  [0.598, 0.587, 0.715]
]