:root {
  color-scheme: light;
  --bg: #f4f6f8;
  --card-bg: #ffffff;
  --border: #d8dee4;
  --text: #1f2933;
  --muted: #6b7684;
  --accent: #2563eb;
  --accent-dark: #1d4ed8;
  --danger: #dc2626;
  --success: #16a34a;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  padding: 32px 16px;
}

main {
  width: 100%;
  max-width: 480px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

h1 {
  font-size: 1.4rem;
  margin: 0 0 4px;
}

h2 {
  font-size: 1.1rem;
  margin: 0 0 12px;
}

p.subtitle {
  color: var(--muted);
  margin: 0 0 20px;
  font-size: 0.9rem;
}

label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 6px;
}

input,
select {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  margin-bottom: 16px;
  background: #fff;
  color: var(--text);
}

input:focus,
select:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

button {
  width: 100%;
  padding: 11px 16px;
  border: none;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
}

button:hover {
  background: var(--accent-dark);
}

button:disabled {
  background: #a8b3bf;
  cursor: not-allowed;
}

button.secondary {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
}

button.link {
  width: auto;
  background: none;
  color: var(--muted);
  text-decoration: underline;
  font-weight: 400;
  padding: 4px 0;
}

.message {
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 0.9rem;
  margin-bottom: 16px;
  display: none;
}

.message.visible {
  display: block;
}

.message.success {
  background: #ecfdf3;
  color: var(--success);
  border: 1px solid #b7ebc6;
}

.message.error {
  background: #fef2f2;
  color: var(--danger);
  border: 1px solid #f3b4b4;
}

.message.info {
  background: #eff6ff;
  color: var(--accent-dark);
  border: 1px solid #bfdbfe;
}

#qr-area {
  text-align: center;
  margin-bottom: 12px;
}

#qr-container {
  display: inline-block;
  max-width: 280px;
  width: 100%;
}

#qr-container svg {
  width: 100%;
  height: auto;
  display: block;
}

.session-code {
  font-family: ui-monospace, Menlo, monospace;
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  color: var(--accent-dark);
}

.session-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 8px;
  cursor: pointer;
}

.session-item:hover {
  border-color: var(--accent);
}

.session-item.active {
  border-color: var(--accent);
  background: #eff6ff;
}

.badge {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 3px 8px;
  border-radius: 999px;
}

.badge.open {
  background: #ecfdf3;
  color: var(--success);
}

.badge.closed {
  background: #f1f5f9;
  color: var(--muted);
}

.attendance-list {
  list-style: none;
  padding: 0;
  margin: 0;
  max-height: 260px;
  overflow-y: auto;
}

.attendance-list li {
  padding: 8px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.9rem;
  display: flex;
  justify-content: space-between;
}

.attendance-list li:last-child {
  border-bottom: none;
}

.count {
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 8px;
}

.row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

[hidden] {
  display: none !important;
}