Monochrome dark red to rusty orange gradient palette editor

/* https://grabient.com/_f3cgDOgBmgVNgJPgA2gBogBhgTTgOCgK9gJn?style=linearGradient&steps=6&angle=270 */

background: linear-gradient(270deg, #8a0710 0.000%, #a21923 20.000%, #b62b25 40.000%, #c43d12 60.000%, #cc4f0f 80.000%, #ce6122 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_f3cgDOgBmgVNgJPgA2gBogBhgTTgOCgK9gJn?style=linearGradient&steps=6&angle=270 -->
            <defs>
              <linearGradient id="gradient" x1="1.000" y1="0.500" x2="0.000" y2="0.500">
        <stop offset="0.000" stop-color="#8a0710" /><stop offset="0.200" stop-color="#a21923" /><stop offset="0.400" stop-color="#b62b25" /><stop offset="0.600" stop-color="#c43d12" /><stop offset="0.800" stop-color="#cc4f0f" /><stop offset="1.000" stop-color="#ce6122" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#8a0710", "#a21923", "#b62b25", "#c43d12", "#cc4f0f", "#ce6122"]

// https://grabient.com/_f3cgDOgBmgVNgJPgA2gBogBhgTTgOCgK9gJn?style=linearGradient&steps=6&angle=270
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 6.0;
const float ANGLE = 270.0;

vec3 palette(float t) {
    vec3 a = vec3(-0.548, 0.206, 0.102);
    vec3 b = vec3(1.357, 0.591, 0.054);
    vec3 c = vec3(0.104, 0.097, 1.235);
    vec3 d = vec3(0.898, 0.701, 0.615);
    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, 0.206, 0.102],
  [1.357, 0.591, 0.054],
  [0.104, 0.097, 1.235],
  [0.898, 0.701, 0.615]
]