body {
  margin:0;
  font-family: Arial, Helvetica, sans-serif;
  background:#f5f5f5;
  color:#222;
}
.app {
  max-width:900px;
  margin:40px auto;
  background:#fff;
  padding:30px;
  border-radius:8px;
  box-shadow:0 2px 8px rgba(0,0,0,.05);
}
h1 { margin-top:0; }
textarea, input {
  width:100%;
  padding:10px;
  margin-top:10px;
}
.btn-primary {
  background:#e5322d;
  border:none;
  color:#fff;
  padding:12px 20px;
  margin-top:15px;
  cursor:pointer;
}
.btn-primary:disabled {
  opacity:0.6;
}
.result {
  margin-top:20px;
}