body {
  font-family: sans-serif;
  margin: 0;
  padding: 1rem;
  background: #121212;
  color: #fff;
}
main {
  max-width: 400px;
  margin: auto;
}
form {
  display: flex;
  flex-direction: column;
}
input, button {
  margin: 0.5rem 0;
  padding: 0.75rem;
  font-size: 1rem;
  border-radius: 5px;
  border: none;
}
button {
  background-color: #4CAF50;
  color: white;
  cursor: pointer;
}
#resultat {
  margin-top: 1rem;
  font-weight: bold;
}