.zh-backtotop {
  position: fixed;
  bottom: 105px;
  right: 1%;
  z-index: 19;
}

.zh-backtotop .btn-action {
  display: block;
  width: 56px;
  height: 56px;
  background-color: #ff5722;
  border-radius: 28px;
  border: 0;
  cursor: pointer;
  position: relative;
  box-shadow: 0 0 4px rgba(0, 0, 0, 0.14), 0 4px 8px rgba(0, 0, 0, 0.2);
  -moz-box-shadow: 0 0 4px rgba(0, 0, 0, 0.14), 0 4px 8px rgba(0, 0, 0, 0.2);
  -webkit-box-shadow: 0 0 4px rgba(0, 0, 0, 0.14), 0 4px 8px rgba(0, 0, 0, 0.2);
}

.zh-backtotop .btn-action:hover {
  background-color: #e24134;
  box-shadow: 0 0 6px rgba(0, 0, 0, 0.16), 0 4px 10px rgba(0, 0, 0, 0.22);
  -moz-box-shadow: 0 0 6px rgba(0, 0, 0, 0.16), 0 4px 10px rgba(0, 0, 0, 0.22);
  -webkit-box-shadow: 0 0 6px rgba(0, 0, 0, 0.16),
    0 4px 10px rgba(0, 0, 0, 0.22);
}

.btn-action + .btn-action {
  margin-top: 5px;
}

.zh-backtotop div {
  position: absolute;
  right: 0;
  left: 0;
  margin: auto;
}

.zh-backtotop .arrow {
  position: absolute;
  top: 16px;
  left: 16px;
}

.btn-donate {
  background-color: #4caf50 !important;
  margin-bottom: 15px;
}

.btn-donate:hover {
  background-color: #3c853f !important;
  box-shadow: 0 0 6px rgba(0, 0, 0, 0.16), 0 4px 10px rgba(0, 0, 0, 0.22);
  -moz-box-shadow: 0 0 6px rgba(0, 0, 0, 0.16), 0 4px 10px rgba(0, 0, 0, 0.22);
  -webkit-box-shadow: 0 0 6px rgba(0, 0, 0, 0.16),
    0 4px 10px rgba(0, 0, 0, 0.22);
}

.icon-donate {
  width: 36px;
  height: 36px;
}

@media (max-width: 1024px) {
  .zh-backtotop {
    margin: auto;
    left: auto;
    right: 1em;
    bottom: 6.5em;
  }
}

@media (max-width: 979px) {
  .zh-backtotop {
    margin: auto;
    left: auto;
    right: 1em;
    bottom: 6.5em;
  }
}

@media (max-width: 768px) {
  .zh-backtotop {
    margin: auto;
    left: auto;
    right: 1em;
    bottom: 6.5em;
  }
}

@media (max-width: 550px) {
  .zh-backtotop .btn-action {
    width: 48px;
    height: 48px;
  }

  .zh-backtotop .arrow {
    top: 12px;
    left: 12px;
  }
}

@media (max-width: 320px) {
  .zh-backtotop .btn-action {
    width: 40px;
    height: 40px;
  }

  .zh-backtotop .arrow {
    top: 8px;
    left: 8px;
  }
}