body {
  width: 93%;
  margin-right: auto;
  margin-left: auto;
}

h1, h2, h3, .copybtn {
  text-align: center;
}

.contents {
  display: flex;
}

.main {
  width: 50%
}

textarea{
  width: 95%;
  white-space: pre-wrap;  
}

.textareaBack {
  word-break: break-word;
  overflow: auto;
  margin-top: 0.1%;
  height: 601px;
  margin-left: 60px;
  width: calc( 88.35% / 2 - 73px);
  padding: 3px;
  z-index: -1;
  position: absolute;
  font-size: 10pt;
  white-space: pre-wrap;
  line-height: 15px;
  font-family: sans-serif;
  color: initial;
}

footer {
  text-align: center;
}
p {
  line-height: 3px;
}

button {
  margin-top: 5px;
  font-size: 18px
}