.auth {
  background: #222;
  padding: 30px;
  border-radius: 12px;
  min-width: 500px;
  margin: 50px auto;
  color: #fff;
  font-size: 18px;
}
.auth h2 {
  text-align: center;
  margin-bottom: 20px;
}

.auth input,
.auth textarea {
  width: 100%;
  padding: 12px;
  margin-top: 6px;
  margin-bottom: 16px;
  border-radius: 8px;
  border: 1px solid #555;
  background: #333;
  color: #fff;
}

.auth button {
  display: block; /* makes the button take full line */
  margin: 0 auto;
}

.auth a.btn {
  display: inline-block;
}