main.css

* {
  box-sizing: border-box;
  margin: 0;
}

a {
  text-decoration: none;
  color: inherit;
}

/* src 為空值或沒有 src 屬性，避免在畫面上顯示預設外框 */
img[src=""], img:not([src]), .btnDownload {
  opacity: 0;
}

img {
  width: auto;
  height: auto;
  max-width: 100%;
  max-height: 100%;
}

label + input {
  display: none;
}

section {
  padding: 1rem;
  text-align: center;
}

section:first-child {
  width: 30%;
}

section:last-child {
  width: 70%;
}

@media ( max-width: 414px ) {
  section:first-child, section:last-child {
    width: 100%;
  }
}

.main {
  display: flex;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 10px;
  border: 2px solid #007AFF;
  outline: none;
  background: #ffffff;
  color: #007AFF;
  margin-bottom: 1rem;
  font-size: 1rem;
  letter-spacing: 1px;
  cursor: pointer;
  transition: all 0.2s;
}

.btn:hover {
  border-radius: 30px;
  transition: all 0.2s;
}

.loading {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  text-align: center;
  z-index: 99;
  background: rgba(0, 0, 0, 0.5);
  color: #ffffff;
  font-size: 30px;
  display: flex;
  justify-content: center;
  align-items: center;
  display: none;
}

.bubbleBlock {
  width:60px;
  height:60px;
  animation: bubbleRotate 2s linear infinite normal both;
}

.bubble {
  display:inline-block;
  position: absolute;
  top: 0;
  width:20px;
  height:20px;
  border-radius:50%;
  background-color:#87cefa;
}

.bubble:nth-child(1){
  animation: bubbleScale 2s 0s infinite alternate both;  
}

.bubble:nth-child(2){
  top: auto;
  bottom: 0;
  animation: bubbleScale 2s 1s infinite alternate both;
}

@keyframes bubbleScale {
  0%{transform:scale(0, 0);}
  100%{transform:scale(1, 1);}
}
@keyframes bubbleRotate {
  0%{transform: rotate(0deg);}

  100%{transform: rotate(360deg);}
}