header.site-headerFrame {
  position: relative;
  overflow: hidden;

  /* 2 star layers + your original background */
  background-image:
    radial-gradient(rgba(255,255,255,0.5) 1px, transparent 1px),   /* far stars */
    radial-gradient(rgba(255,255,255,0.8) 1.2px, transparent 1px), /* closer stars */
    inherit;

  /* fewer stars = bigger spacing */
  background-size:
    220px 220px,
    140px 140px,
    auto;

  background-repeat:
    repeat,
    repeat,
    no-repeat;

  animation: starDrift 240s linear infinite;
}

/* subtle layered movement */
@keyframes starDrift {
  from {
    background-position:
      0 0,        /* far stars */
      0 0,        /* close stars */
      center;     /* original background */
  }
  to {
    background-position:
      -80px -40px,   /* far stars move VERY little */
      -160px -80px,  /* closer stars move more */
      center;
  }
}