body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}
.page {
  margin: 10px 20px 10px 10px;
  display: grid;
  grid-template-columns: 50% 50%;
  column-gap: 10px;
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
}
.source {
  background-color: cornflowerblue;
  position: relative;
}
.source button {
  background-color: darkslateblue;
}
.output {
  background-color: #373d42;
  position: relative;
}
.output button {
  background-color: #738089;
}
h1 {
  color: white;
  font-size: 16px;
  margin-left: 10px;
}
.buttons {
  position: absolute;
  top: 10px;
  right: 10px;
}
button {
  border: none;
  color: white;
  padding: 10px;
  display: inline-block;
  min-width: 80px;
  margin-left: 5px;
  cursor: pointer;
}
textarea {
  position: absolute;
  top: 60px;
  left: 5px;
  right: 5px;
  bottom: 5px;
  padding: 10px;
}