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

.box {
  width: 50%;
  height: 100%;
  /*padding: 20px;*/
  float: left;
}

textarea {
  font-family: Consolas, 'Microsoft Yahei UI', monospace;
}

body, html {
  height: 100%;
}

#select {
  margin: 10px;
}

.tools {
  display: flex;
  justify-content: center;
}

button {
  margin: 10px;
}