:root {
  --depths: #060a0e;
  --shore:  #08100c;
}

.chapter-header {
  background:
    radial-gradient(ellipse 100% 60% at 50% 100%, #183858 0%, transparent 65%),
    radial-gradient(ellipse 70% 50% at 70% 50%, #203050 0%, transparent 60%),
    #162040;
}

.chapter-header::after {
  background: radial-gradient(ellipse 80% 100% at 50% 0%, transparent 40%, rgba(6,8,16,0.45) 100%);
}