.pdf-btn {
  position: fixed;
  right: .2rem;
  bottom: .4rem;
  width: 1.3rem;
  height: 1.3rem;
  cursor: pointer;
}
.mask {
  display: none;
  position: fixed;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  z-index: 999;
  width: 100%;
  height: 100vh;
  background-color: rgba(0,0,0,.5);
}
.mask .content {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 2.8rem;
  height: 2.8rem;
  border-radius: .2rem;
  background-color: #333;
  color: #d5bcbc;
}
.mask .content .loading {
  width: .8rem;
  height: .8rem;
  border: .08rem solid #f3f3f3; /* Light grey */
  border-top: .08rem solid #3498db; /* Blue */
  border-radius: 50%;
  animation: spin 1s linear infinite;
}
.mask .content .text {
  margin-top: .2rem;
  font-size: .26rem;
  color: #fff;
}
@keyframes spin {
  0% { transform: rotate(0deg); }
  50% { transform: rotate(180deg); }
  100% { transform: rotate(360deg); }
}