/* https://grabient.com/_f6wf49gUygWfgV5gM9gBjgBkgBmgL8gMjgIC?style=linearGradient&steps=5&angle=225 */

background: linear-gradient(225deg, #000281 0.000%, #033586 25.000%, #396491 50.000%, #6c8ea1 75.000%, #9ab2b5 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_f6wf49gUygWfgV5gM9gBjgBkgBmgL8gMjgIC?style=linearGradient&steps=5&angle=225 -->
            <defs>
              <linearGradient id="gradient" x1="0.854" y1="0.146" x2="0.146" y2="0.854">
        <stop offset="0.000" stop-color="#000281" /><stop offset="0.250" stop-color="#033586" /><stop offset="0.500" stop-color="#396491" /><stop offset="0.750" stop-color="#6c8ea1" /><stop offset="1.000" stop-color="#9ab2b5" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#000281", "#033586", "#396491", "#6c8ea1", "#9ab2b5"]

// https://grabient.com/_f6wf49gUygWfgV5gM9gBjgBkgBmgL8gMjgIC?style=linearGradient&steps=5&angle=225
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 5.0;
const float ANGLE = 225.0;

vec3 palette(float t) {
    vec3 a = vec3(-0.336, -0.451, 1.330);
    vec3 b = vec3(1.439, 1.401, 0.829);
    vec3 c = vec3(0.099, 0.100, 0.102);
    vec3 d = vec3(0.764, 0.803, 0.514);
    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);
}

[
  [-0.336, -0.451, 1.330],
  [1.439, 1.401, 0.829],
  [0.099, 0.100, 0.102],
  [0.764, 0.803, 0.514]
]

Gradient palette editor — #000281 to #9ab2b5