.stlfpb{
  position: fixed;
  z-index: 9999;
  padding: 12px 16px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,.18);
  background: rgba(20,20,20,.92);
  color: #fff;
  font-weight: 900;
  letter-spacing: .2px;
  text-decoration: none !important;
  box-shadow: 0 10px 24px rgba(0,0,0,.25), 0 0 18px rgba(120,255,220,.10);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: transform .08s ease, filter .15s ease, box-shadow .15s ease, opacity .15s ease;
  opacity: .96;
}
.stlfpb:hover{
  transform: translateY(-1px);
  filter: brightness(1.08);
  box-shadow: 0 12px 28px rgba(0,0,0,.28), 0 0 26px rgba(120,255,220,.16);
}
.stlfpb:active{ transform: translateY(0px); opacity:.92; }

.stlfpb-br{ right: 18px; bottom: 18px; }
.stlfpb-bl{ left: 18px; bottom: 18px; }
.stlfpb-tr{ right: 18px; top: 18px; }
.stlfpb-tl{ left: 18px; top: 18px; }

@media (max-width: 480px){
  .stlfpb-br{ right: 12px; bottom: 12px; }
  .stlfpb-bl{ left: 12px; bottom: 12px; }
  .stlfpb-tr{ right: 12px; top: 12px; }
  .stlfpb-tl{ left: 12px; top: 12px; }
}