* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Segoe UI", Arial, sans-serif;
  background: #f2f4f8;
  color: #1f2937;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 2rem 1rem;
}

header {
  text-align: center;
  margin-bottom: 1.5rem;
}

h1 {
  font-size: 1.6rem;
  color: #00543d;
}

.subtitle {
  font-size: 0.85rem;
  color: #6b7280;
  margin-top: 0.3rem;
}

main {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
  max-width: 1000px;
}

.card {
  background: #ffffff;
  border-radius: 8px;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.1);
  padding: 1.25rem;
  width: 300px;
  display: flex;
  flex-direction: column;
}

.card h2 {
  font-size: 1rem;
  margin-bottom: 0.9rem;
  color: #00543d;
}

label {
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}

input {
  padding: 0.5rem;
  margin-bottom: 0.75rem;
  border: 1px solid #d1d5db;
  border-radius: 5px;
  font-size: 0.9rem;
}

button {
  padding: 0.55rem;
  background: #00543d;
  color: #ffffff;
  border: none;
  border-radius: 5px;
  font-size: 0.9rem;
  cursor: pointer;
}

button:hover {
  background: #007a5a;
}

.result {
  margin-top: 0.75rem;
  font-size: 0.85rem;
  min-height: 1.2rem;
  white-space: pre-line;
}

.result.success {
  color: #047857;
  font-weight: 600;
}

.result.error {
  color: #b91c1c;
  font-weight: 600;
}

.code-display {
  font-size: 1.4rem;
  letter-spacing: 0.3rem;
  font-weight: 700;
  color: #1f2937;
}

footer {
  margin-top: 2rem;
  font-size: 0.75rem;
  color: #6b7280;
  text-align: center;
}