/* back-to-top.css */
:root{ --bt-size:56px; --bt-right:24px; --bt-bottom:24px; --bt-z:9999; }

.back-to-top {
  position:fixed;
  right:var(--bt-right);
  bottom:var(--bt-bottom);
  width:var(--bt-size);
  height:var(--bt-size);
  border-radius:50%;
  box-shadow:0 6px 14px rgba(0,0,0,.18);
  opacity:0;
  transform:translateY(12px);
  transition:opacity .22s ease, transform .22s ease;
  z-index:var(--bt-z);
  display:flex;
  align-items:center;
  justify-content:center;
  background:transparent;
  border:none;
  cursor:pointer;
  outline:none;
}
.back-to-top.show{ opacity:1; transform:translateY(0); }
.back-to-top img{ width:100%; height:100%; object-fit:cover; border-radius:50%; display:block; }
.back-to-top:focus{ outline:3px solid rgba(0,123,255,.25); outline-offset:4px; }
@media (max-width:399px){ .back-to-top{ display:none !important; } }