/* https://grabient.com/_gX-g2wfPfgW3gwgg89gBmgBngBkgIIgH3gOe?style=linearGradient&steps=5&angle=225 */

background: linear-gradient(225deg, #156661 0.000%, #21739c 25.000%, #3794c0 50.000%, #55c9cb 75.000%, #7affbe 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gX-g2wfPfgW3gwgg89gBmgBngBkgIIgH3gOe?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="#156661" /><stop offset="0.250" stop-color="#21739c" /><stop offset="0.500" stop-color="#3794c0" /><stop offset="0.750" stop-color="#55c9cb" /><stop offset="1.000" stop-color="#7affbe" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#156661", "#21739c", "#3794c0", "#55c9cb", "#7affbe"]

// https://grabient.com/_gX-g2wfPfgW3gwgg89gBmgBngBkgIIgH3gOe?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(1.534, 3.504, -3.105);
    vec3 b = vec3(1.463, 3.104, 3.901);
    vec3 c = vec3(0.102, 0.103, 0.100);
    vec3 d = vec3(0.520, 0.503, 0.926);
    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);
}

[
  [1.534, 3.504, -3.105],
  [1.463, 3.104, 3.901],
  [0.102, 0.103, 0.100],
  [0.520, 0.503, 0.926]
]

Gradient palette editor — #156661 to #7affbe