* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 24px;
  font-family: Arial, sans-serif;
  color: #222;
  background: #f4f4f4;
}

main {
  max-width: 420px;
  margin: 40px auto;
  padding: 24px;
  background: white;
  border: 1px solid #ddd;
  border-radius: 8px;
}

h1 {
  margin-top: 0;
}

form {
  display: grid;
  gap: 10px;
  margin: 24px 0;
}

input,
select,
button {
  width: 100%;
  padding: 10px;
  font: inherit;
}

button {
  margin-top: 8px;
  color: white;
  background: #2458a6;
  border: 0;
  border-radius: 4px;
  cursor: pointer;
}

button:disabled {
  opacity: 0.6;
  cursor: wait;
}

#result {
  font-weight: bold;
}

#feedback {
  color: #a52727;
}