<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" role="img" aria-label="Nocturne">
  <defs>
    <linearGradient id="n" x1="0" y1="0" x2="0" y2="1">
      <stop offset="0" stop-color="#312e81"/>
      <stop offset="1" stop-color="#0f0d29"/>
    </linearGradient>
  </defs>
  <rect width="64" height="64" rx="16" fill="url(#n)"/>
  <!-- A crescent, cut rather than drawn: one circle with another taken out
       of it, which is how the moon actually does it. -->
  <path d="M40 14 A18 18 0 1 0 40 50 A15 15 0 1 1 40 14 Z" fill="#a78bfa"/>
  <circle cx="19" cy="20" r="1.4" fill="#ddd6fe"/>
  <circle cx="47" cy="27" r="1.1" fill="#ddd6fe" opacity="0.8"/>
  <circle cx="44" cy="45" r="1.6" fill="#ddd6fe" opacity="0.6"/>
</svg>