/* https://grabient.com/_gBzgtYghogTsgtXgh8gBogBngBjgL5gH1gHJ?style=linearGradient&steps=5&angle=315 */

background: linear-gradient(315deg, #34000f 0.000%, #670b00 25.000%, #992800 50.000%, #c85806 75.000%, #f2991d 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gBzgtYghogTsgtXgh8gBogBngBjgL5gH1gHJ?style=linearGradient&steps=5&angle=315 -->
            <defs>
              <linearGradient id="gradient" x1="0.854" y1="0.854" x2="0.146" y2="0.146">
        <stop offset="0.000" stop-color="#34000f" /><stop offset="0.250" stop-color="#670b00" /><stop offset="0.500" stop-color="#992800" /><stop offset="0.750" stop-color="#c85806" /><stop offset="1.000" stop-color="#f2991d" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#34000f", "#670b00", "#992800", "#c85806", "#f2991d"]

// https://grabient.com/_gBzgtYghogTsgtXgh8gBogBngBjgL5gH1gHJ?style=linearGradient&steps=5&angle=315
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 5.0;
const float ANGLE = 315.0;

vec3 palette(float t) {
    vec3 a = vec3(0.115, 2.904, 2.152);
    vec3 b = vec3(1.260, 2.903, 2.172);
    vec3 c = vec3(0.104, 0.103, 0.099);
    vec3 d = vec3(0.761, 0.501, 0.457);
    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);
}

[
  [0.115, 2.904, 2.152],
  [1.260, 2.903, 2.172],
  [0.104, 0.103, 0.099],
  [0.761, 0.501, 0.457]
]

Gradient palette editor — #34000f to #f2991d