.product-fixed-atc {
  display: block;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: #fff;
  padding: 10px;
  box-shadow: 0 -2px 5px #0000000f;
  transform: translateY(100%);
  transition: transform 0.3s ease;
}

.product-fixed-atc.visible {
  transform: translateY(0);
}

.product-fixed-atc .btn {
  width: 100%;
}