*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: system-ui, sans-serif;
  background: #f5f5f5;
}

main {
  background: white;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  width: 100%;
  max-width: 360px;
}

h1 {
  margin: 0 0 1.5rem;
  font-size: 1.25rem;
}

input {
  display: block;
  width: 100%;
  padding: 0.5rem 0.75rem;
  margin-bottom: 0.75rem;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-size: 1rem;
}

button {
  display: block;
  width: 100%;
  padding: 0.5rem;
  background: #333;
  color: white;
  border: none;
  border-radius: 4px;
  font-size: 1rem;
  cursor: pointer;
}

button:hover { background: #555; }

#error {
  margin: 0.75rem 0 0;
  color: #c00;
  font-size: 0.875rem;
}