html {
  height: 100%;
}

body {
  height: 100%;
  margin: 0;
  padding: 0;
  font-family: arial, verdana, sans-serif;
}

textarea {
  width: 100%;
  height: 100%;
  font-size: 1em;
  padding: 2.5em;
  border: 0;
  box-sizing: border-box;
}