.scroll-top-btn{
  position:fixed;
  left:14px;
  bottom:14px;
  width:42px;
  height:42px;
  border-radius:14px;
  border:1px solid rgba(224,71,77,.18);
  background:linear-gradient(180deg, rgba(54,33,37,.92), rgba(38,40,45,.9));
  color:#ece7de;
  display:none;
  align-items:center;
  justify-content:center;
  box-shadow:0 14px 30px rgba(0,0,0,.2);
  z-index:459;
  opacity:0;
  transform:translateY(10px);
  transition:opacity .22s ease, transform .22s ease, border-color .22s ease, background .22s ease, box-shadow .22s ease;
  cursor:pointer;
  pointer-events:none;
}
.scroll-top-btn.is-visible{
  display:flex;
  opacity:1;
  transform:translateY(0);
  pointer-events:auto;
}
.scroll-top-btn:hover{
  border-color:rgba(224,71,77,.42);
  background:linear-gradient(180deg, rgba(90,30,36,.94), rgba(42,43,48,.94));
  box-shadow:0 18px 34px rgba(0,0,0,.24), 0 0 18px rgba(184,29,36,.16);
}
.scroll-top-btn svg{
  width:17px;
  height:17px;
  display:block;
  flex-shrink:0;
}
@media (min-width: 769px){
  .scroll-top-btn{
    left:20px;
    bottom:20px;
  }
}
@media (max-width:768px){
  .scroll-top-btn{
    left:12px;
    bottom:calc(12px + env(safe-area-inset-bottom));
    border-color:rgba(224,71,77,.28);
    box-shadow:0 14px 30px rgba(0,0,0,.2),0 0 16px rgba(184,29,36,.12);
  }
}