.hbb-back-btn{
  position:fixed;
  right:16px;
  bottom:16px;
  width:44px;
  height:44px;
  border-radius:9999px;
  border:none;
  outline:none;
  background:#000;
  color:#fff;
  box-shadow:0 4px 10px rgba(0,0,0,.15);
  display:flex;
  align-items:center;
  justify-content:center;
  cursor:pointer;
  z-index:9999;
  opacity:.92;
  transition:transform .15s ease, opacity .2s ease, box-shadow .2s ease;
  font-family:inherit;
  line-height:1;
}
.hbb-text{ font-size:12px; font-weight:600; letter-spacing:.2px; }
.hbb-back-btn:hover{ transform:translateY(-1px); opacity:1; box-shadow:0 6px 14px rgba(0,0,0,.18); }
.hbb-back-btn:active{ transform:translateY(0); opacity:.9; }

/* Smaller on very small screens */
@media (max-width: 360px){
  .hbb-back-btn{ width:40px; height:40px; right:12px; bottom:12px; }
  .hbb-back-btn .hbb-icon{ width:16px; height:16px; }
  .hbb-back-btn .hbb-text{ font-size:11px; }
}

/* Hide on >=768px if mobile-only toggle is ON (class applied by PHP) */
@media (min-width: 768px){
  .hbb-back-btn.hbb-mobile-only{ display:none; }
}