use a pride flag as the header background

nav {
  overflow-x: hidden;
  position: relative;
}

nav::before {
  content: '';
  position: absolute;
  top: 0;
  right: -88em;
  bottom: 0;
  left: 0;
  display: block;
  background: repeating-linear-gradient(
    2rad,
    #be3027, #be3027 10em,
    #ed6d32 10em, #ed6d32 20em,
    #f5c744 20em, #f5c744 30em,
    #49a143 30em, #49a143 40em,
    #194783 40em, #194783 50em,
    #95337b 50em, #95337b 60em,
    #0a0a06 60em, #0a0a06 70em,
    #715142 70em, #715142 80em
  );
  pointer-events: none;
  animation: 20s linear infinite rainbow-bg-anim;
  z-index: -1;
}

nav .top {
  background: transparent;
}

nav .links {
  background: rgba(0, 0, 0, 0.3);
}

@keyframes rainbow-bg-anim {
  to {
    transform: translateX(-88em);
  }
}