/* https://grabient.com/_f-8gIyenwgBPgHkhosgBhgJcgBngP2gIPgOd?style=linearGradient&steps=6&angle=315 */

background: linear-gradient(315deg, #031652 0.000%, #0245a9 20.000%, #029ee6 40.000%, #01eeff 60.000%, #00ffff 80.000%, #00e3f2 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_f-8gIyenwgBPgHkhosgBhgJcgBngP2gIPgOd?style=linearGradient&steps=6&angle=315 -->
            <defs>
              <linearGradient id="gradient" x1="0.854" y1="0.854" x2="0.146" y2="0.146">
        <stop offset="0.000" stop-color="#031652" /><stop offset="0.200" stop-color="#0245a9" /><stop offset="0.400" stop-color="#029ee6" /><stop offset="0.600" stop-color="#01eeff" /><stop offset="0.800" stop-color="#00ffff" /><stop offset="1.000" stop-color="#00e3f2" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#031652", "#0245a9", "#029ee6", "#01eeff", "#00ffff", "#00e3f2"]

// https://grabient.com/_f-8gIyenwgBPgHkhosgBhgJcgBngP2gIPgOd?style=linearGradient&steps=6&angle=315
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 6.0;
const float ANGLE = 315.0;

vec3 palette(float t) {
    vec3 a = vec3(-0.068, 0.562, -5.648);
    vec3 b = vec3(0.079, 0.484, 6.700);
    vec3 c = vec3(0.097, 0.604, 0.103);
    vec3 d = vec3(1.014, 0.527, 0.925);
    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);
}

[
  [-0.068, 0.562, -5.648],
  [0.079, 0.484, 6.700],
  [0.097, 0.604, 0.103],
  [1.014, 0.527, 0.925]
]

Gradient palette editor — #031652 to #00e3f2