/* https://grabient.com/_gHJgHVgDYgHsgHGgDggNhgMZgNWgKEgIPg1IiZ21oJgA?style=linearGradient&steps=7&angle=90 */

background: linear-gradient(90deg, #2a001b 0.000%, #78130c 16.667%, #ce480e 33.333%, #ff8d22 50.000%, #ffd543 66.667%, #ffff69 83.333%, #ffff8d 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gHJgHVgDYgHsgHGgDggNhgMZgNWgKEgIPg1IiZ21oJgA?style=linearGradient&steps=7&angle=90 -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#2a001b" /><stop offset="0.167" stop-color="#78130c" /><stop offset="0.333" stop-color="#ce480e" /><stop offset="0.500" stop-color="#ff8d22" /><stop offset="0.667" stop-color="#ffd543" /><stop offset="0.833" stop-color="#ffff69" /><stop offset="1.000" stop-color="#ffff8d" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#2a001b", "#78130c", "#ce480e", "#ff8d22", "#ffd543", "#ffff69", "#ffff8d"]

// https://grabient.com/_gHJgHVgDYgHsgHGgDggNhgMZgNWgKEgIPg1IiZ21oJgA?style=linearGradient&steps=7&angle=90
// 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(0.610, 0.622, 0.369);
    vec3 b = vec3(0.719, 0.663, 0.327);
    vec3 c = vec3(0.451, 0.413, 0.445);
    vec3 d = vec3(0.644, 0.527, 3.400);
    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);
}

[
  [0.610, 0.622, 0.369],
  [0.719, 0.663, 0.327],
  [0.451, 0.413, 0.445],
  [0.644, 0.527, 3.400]
]

Gradient palette editor — #2a001b to #ffff8d