Deep turquoise to gray blue to charcoal gray gradient palette editor

/* https://grabient.com/_gEygGLgHGgCPgC_gDQgPEgMzgMQgK4gMXgLm */

background: linear-gradient(90deg, #427171 0.000%, #659099 16.667%, #7292a9 33.333%, #5e7497 50.000%, #3b4b6f 66.667%, #2a354a 83.333%, #3a3f3f 100.000%);

<svg xmlns="http://www.w3.org/2000/svg" width="800" height="400" viewBox="0 0 800 400" preserveAspectRatio="none">
            <!-- https://grabient.com/_gEygGLgHGgCPgC_gDQgPEgMzgMQgK4gMXgLm -->
            <defs>
              <linearGradient id="gradient" x1="0.000" y1="0.500" x2="1.000" y2="0.500">
        <stop offset="0.000" stop-color="#427171" /><stop offset="0.167" stop-color="#659099" /><stop offset="0.333" stop-color="#7292a9" /><stop offset="0.500" stop-color="#5e7497" /><stop offset="0.667" stop-color="#3b4b6f" /><stop offset="0.833" stop-color="#2a354a" /><stop offset="1.000" stop-color="#3a3f3f" />
              </linearGradient>
            </defs>
            <rect x="0" y="0" width="800" height="400" fill="url(#gradient)" />
          </svg>

["#427171", "#659099", "#7292a9", "#5e7497", "#3b4b6f", "#2a354a", "#3a3f3f"]

// https://grabient.com/_gEygGLgHGgCPgC_gDQgPEgMzgMQgK4gMXgLm
// cosine gradient palette — https://iquilezles.org/articles/palettes/
const float STEPS = 7.0;
const float ANGLE = 90.0;

vec3 palette(float t) {
    vec3 a = vec3(0.306, 0.395, 0.454);
    vec3 b = vec3(0.143, 0.191, 0.208);
    vec3 c = vec3(0.964, 0.819, 0.784);
    vec3 d = vec3(0.696, 0.791, 0.742);
    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);
}

[
  [0.306, 0.395, 0.454],
  [0.143, 0.191, 0.208],
  [0.964, 0.819, 0.784],
  [0.696, 0.791, 0.742]
]