body, html {
  height: 100%;
}

header {
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  width: 100%;
}

section {
  position: absolute;
  left: 0;
  top: 56px;
  right: 0;
  bottom: 0;
  width: 100%;
  padding: 16px;
}

div.panel {
  margin: 0;
  padding: 8px;
  transition: background-color .2s;
}

div.panel > center > button {
  display: inline-block;
  cursor: pointer;
  margin: 2px;
  content: ".";
  font-size: 0;
  width: 12px;
  height: 12px;
  border-radius: 100%;
  border: none;
  padding: 0;
}

div.preview {
  display: flex;
  flex-direction: row;
  justify-content: space-between;
  align-items: top;
}

code.code {
  display: bloc;
}