body {
  background: lightblue;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
    Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

main {
  background-color: #fff;
  border-radius: 2rem;
  margin: 4rem auto;
  max-width: 40rem;
  padding: 2rem;
}

h1 {
  margin-top: 0;
}

form .input {
  display: flex;
  gap: 0.5rem;
}

form .result {
  color: green;
  display: inline-block;
  font-size: 1.4em;
  font-weight: bold;
  margin-top: 1rem;
}

form.-invalid .result {
  color: red;
}
form.-invalid input {
  border-color: red;
}

button {
  background-color: #0c7a9e;
  border-radius: 0.5rem;
  border: none;
  color: #fff;
  cursor: pointer;
  font: inherit;
  padding: 0.5rem 1rem;
}

button:hover {
  background-color: #0a6280;
}

input {
  border-radius: 0.5rem;
  border: 2px solid #aaa;
  flex: 1;
  font: inherit;
  padding: 0.5rem;
}

dd {
  font-weight: bold;
}