Gradient palette editor — #010010 to #ff1809

/* https://grabient.com/_gItgBngBSgJCgCLgCEgHFgTZgPEgHFgH1gLX */

background: linear-gradient(90deg, #010010 0.000%, #00112f 16.667%, #193935 33.333%, #4f341d 50.000%, #930a00 66.667%, #d50000 83.333%, #ff1809 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gItgBngBSgJCgCLgCEgHFgTZgPEgHFgH1gLX -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#010010" /><stop offset="0.167" stop-color="#00112f" /><stop offset="0.333" stop-color="#193935" /><stop offset="0.500" stop-color="#4f341d" /><stop offset="0.667" stop-color="#930a00" /><stop offset="0.833" stop-color="#d50000" /><stop offset="1.000" stop-color="#ff1809" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#010010", "#00112f", "#193935", "#4f341d", "#930a00", "#d50000", "#ff1809"]

// https://grabient.com/_gItgBngBSgJCgCLgCEgHFgTZgPEgHFgH1gLX
// 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(0.557, 0.103, 0.082);
    vec3 b = vec3(0.578, 0.139, 0.132);
    vec3 c = vec3(0.453, 1.241, 0.964);
    vec3 d = vec3(0.453, 0.501, 0.727);
    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);
}

[
  [0.557, 0.103, 0.082],
  [0.578, 0.139, 0.132],
  [0.453, 1.241, 0.964],
  [0.453, 0.501, 0.727]
]