:root {
  --bg: #f4f7fb;
  --panel: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --border: #dbe3ee;
  --error-bg: #fef2f2;
  --error-border: #fecaca;
  --error-text: #991b1b;
  --success-bg: #ecfdf5;
  --success-border: #a7f3d0;
  --success-text: #065f46;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 32px 16px;
  font-family: Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.container {
  max-width: 720px;
  margin: 0 auto;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 28px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}

h1 {
  margin: 0 0 10px 0;
  font-size: 28px;
  line-height: 1.2;
}

.subtitle {
  margin: 0 0 24px 0;
  color: var(--muted);
  font-size: 15px;
}

label {
  display: block;
  margin-bottom: 10px;
  font-weight: bold;
  font-size: 14px;
}

input[type="file"] {
  display: block;
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
}

.actions {
  margin-top: 18px;
  display: flex;
  gap: 12px;
  align-items: center;
  flex-wrap: wrap;
}

button {
  background-color: var(--primary);
  color: white;
  border: none;
  padding: 12px 18px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 14px;
  font-weight: bold;
}

button:hover {
  background-color: var(--primary-hover);
}

.note {
  color: var(--muted);
  font-size: 13px;
  margin-top: 14px;
}

.alert {
  border-radius: 10px;
  padding: 14px 16px;
  margin-bottom: 20px;
  border: 1px solid transparent;
}

.alert.error {
  background: var(--error-bg);
  border-color: var(--error-border);
  color: var(--error-text);
}

.alert.success {
  background: var(--success-bg);
  border-color: var(--success-border);
  color: var(--success-text);
}

.alert-title {
  font-weight: bold;
  margin-bottom: 6px;
}

.footer-link {
  display: inline-block;
  margin-top: 18px;
  color: var(--primary);
  text-decoration: none;
  font-weight: bold;
}

.footer-link:hover {
  text-decoration: underline;
}

.code-list {
  margin: 8px 0 0 18px;
  padding: 0;
  font-size: 14px;
}