/* === SCROLL-TO-TOP  (26-04-2025) ======================== */
.scroll-top-btn{
  position:fixed;
  bottom:calc(24px + env(safe-area-inset-bottom));
  right:24px;
  z-index:999;
  display:inline-flex;align-items:center;justify-content:center;
  width:clamp(42px,4.5vw,48px);
  aspect-ratio:1;
  border:none;border-radius:50%;
  font-size:clamp(1.2rem,2.2vw,.0rem + 1.5rem);
  font-weight:700;cursor:pointer;
  background:var(--primary-color,#3b82f6);color:#fff;
  box-shadow:0 4px 14px rgba(0,0,0,.2);
  opacity:0;pointer-events:none;
  transition:opacity .3s,transform .3s,background .3s;
}
.scroll-top-btn:hover{
  transform:translateY(-4px);
  background:var(--primary-dark,#2563eb);
}
.scroll-top-btn.show{
  opacity:1;pointer-events:auto;
}

/* iOS / Android маленькі екрани ≤480 px */
@media (max-width:480px){
  .scroll-top-btn{
    bottom:calc(16px + env(safe-area-inset-bottom));
    right:16px;
  }
}

/* accessibility: без анімації, якщо користувач її вимкнув */
@media (prefers-reduced-motion:reduce){
  .scroll-top-btn{transition:none;}
}