/* https://grabient.com/_gGze7LhE7gHjhRMhBTgM2gBngBlgG4gOEgIN?style=linearGradient&steps=6&angle=135 */

background: linear-gradient(135deg, #000048 0.000%, #0d2866 20.000%, #7d7094 40.000%, #dfa4d2 60.000%, #d4c2ff 80.000%, #66c9ff 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gGze7LhE7gHjhRMhBTgM2gBngBlgG4gOEgIN?style=linearGradient&steps=6&angle=135 -->
            <defs>
              <linearGradient id="gradient" x1="0.146" y1="0.146" x2="0.854" y2="0.854">
        <stop offset="0.000" stop-color="#000048" /><stop offset="0.200" stop-color="#0d2866" /><stop offset="0.400" stop-color="#7d7094" /><stop offset="0.600" stop-color="#dfa4d2" /><stop offset="0.800" stop-color="#d4c2ff" /><stop offset="1.000" stop-color="#66c9ff" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#000048", "#0d2866", "#7d7094", "#dfa4d2", "#d4c2ff", "#66c9ff"]

// https://grabient.com/_gGze7LhE7gHjhRMhBTgM2gBngBlgG4gOEgIN?style=linearGradient&steps=6&angle=135
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 6.0;
const float ANGLE = 135.0;

vec3 palette(float t) {
    vec3 a = vec3(0.435, -4.405, 4.411);
    vec3 b = vec3(0.483, 5.196, 4.179);
    vec3 c = vec3(0.822, 0.103, 0.101);
    vec3 d = vec3(0.440, 0.900, 0.525);
    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);
}

[
  [0.435, -4.405, 4.411],
  [0.483, 5.196, 4.179],
  [0.822, 0.103, 0.101],
  [0.440, 0.900, 0.525]
]

Gradient palette editor — #000048 to #66c9ff