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

:root {
  --bg: #f5f5f5;
  --card-bg: #ffffff;
  --text: #1a1a1a;
  --text-secondary: #555555;
  --primary: #1565c0;
  --primary-dark: #0d47a1;
  --success: #2e7d32;
  --warning: #e65100;
  --danger: #c62828;
  --border: #dddddd;
  --radius: 12px;
}

html {
  font-size: 18px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
  -webkit-text-size-adjust: 100%;
}

#app {
  max-width: 480px;
  margin: 0 auto;
  padding: 1rem;
  padding-bottom: 5rem;
}

.page {
  animation: fadeIn 0.2s ease;
}

.hidden {
  display: none !important;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

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

.header h1 {
  font-size: 1.8rem;
  font-weight: 700;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-top: 0.25rem;
}

.form {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

label {
  font-weight: 600;
  font-size: 0.95rem;
}

input[type="email"],
input[type="password"],
input[type="text"],
input[type="time"],
select {
  width: 100%;
  padding: 0.85rem 1rem;
  font-size: 1rem;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  background: var(--card-bg);
  color: var(--text);
  -webkit-appearance: none;
  appearance: none;
}

input[type="text"] {
  font-size: 1.2rem;
  padding: 1rem 1.2rem;
  min-height: 56px;
}

input:focus, select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(21, 101, 192, 0.2);
}

select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23555' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 1rem center;
  padding-right: 2.5rem;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 500;
  cursor: pointer;
}

.checkbox-label input[type="checkbox"] {
  width: 24px;
  height: 24px;
  accent-color: var(--primary);
}

.btn {
  display: block;
  width: 100%;
  padding: 1rem;
  font-size: 1.1rem;
  font-weight: 700;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  min-height: 56px;
}

.btn:active {
  transform: scale(0.98);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover:not(:disabled) {
  background: var(--primary-dark);
}

.btn-warning {
  background: var(--warning);
  color: white;
}

.btn-danger {
  background: var(--danger);
  color: white;
}

.error {
  color: var(--danger);
  font-weight: 600;
  text-align: center;
  min-height: 1.5rem;
}

.message {
  font-weight: 600;
  text-align: center;
  min-height: 1.5rem;
  padding: 0.5rem;
}

.message.success {
  color: var(--success);
}

.message.error {
  color: var(--danger);
}

.info-box {
  background: var(--primary);
  color: white;
  padding: 1rem;
  border-radius: var(--radius);
  text-align: center;
  font-weight: 600;
  margin-bottom: 1rem;
}

.card-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.card {
  background: var(--card-bg);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 0.5rem;
}

.card-title {
  font-size: 1.1rem;
  font-weight: 700;
}

.card-status {
  font-size: 1.4rem;
}

.card-body {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 0.75rem;
}

.card-days {
  display: flex;
  gap: 0.35rem;
  flex-wrap: wrap;
  margin-bottom: 0.75rem;
}

.day-tag {
  background: var(--primary);
  color: white;
  padding: 0.25rem 0.6rem;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
}

.card-actions {
  display: flex;
  gap: 0.5rem;
}

.card-btn {
  flex: 1;
  padding: 0.6rem;
  font-size: 0.9rem;
  font-weight: 600;
  border: 2px solid var(--border);
  border-radius: 8px;
  background: var(--card-bg);
  color: var(--text);
  cursor: pointer;
}

.card-btn:hover {
  background: var(--bg);
}

.card-btn.danger {
  color: var(--danger);
  border-color: var(--danger);
}

.card-btn.toggle {
  color: var(--primary);
  border-color: var(--primary);
}

.empty-state {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-secondary);
}

.empty-state .small {
  font-size: 0.85rem;
  margin-top: 0.5rem;
}

.day-picker {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.day-btn {
  flex: 1;
  min-width: 48px;
  padding: 0.75rem 0.25rem;
  font-size: 0.85rem;
  font-weight: 700;
  border: 2px solid var(--border);
  border-radius: 8px;
  background: var(--card-bg);
  color: var(--text);
  cursor: pointer;
  text-align: center;
}

.day-btn.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.class-info {
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  font-size: 0.9rem;
}

.class-info strong {
  display: block;
  margin-bottom: 0.25rem;
}

.class-list {
  max-height: 320px;
  overflow-y: auto;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  background: var(--card-bg);
}

.class-list:empty {
  display: none;
}

.class-item {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  cursor: pointer;
  transition: background 0.1s;
}

.class-item:last-child {
  border-bottom: none;
}

.class-item:hover {
  background: var(--bg);
}

.class-item.selected {
  background: #e3f2fd;
  border-left: 4px solid var(--primary);
}

.class-item-name {
  font-weight: 700;
  font-size: 1rem;
}

.class-item-meta {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-top: 0.2rem;
}

.class-item-availability {
  font-size: 0.8rem;
  font-weight: 600;
  margin-top: 0.2rem;
}

.class-item-availability.full {
  color: var(--danger);
}

.class-item-availability.available {
  color: var(--success);
}

.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--card-bg);
  border-top: 2px solid var(--border);
  display: flex;
  max-width: 480px;
  margin: 0 auto;
}

.nav-btn {
  flex: 1;
  padding: 0.75rem 0.25rem;
  font-size: 0.75rem;
  font-weight: 600;
  border: none;
  background: none;
  color: var(--text-secondary);
  cursor: pointer;
  text-align: center;
}

.nav-btn.active {
  color: var(--primary);
  border-bottom: 3px solid var(--primary);
}

hr {
  border: none;
  border-top: 2px solid var(--border);
  margin: 0.5rem 0;
}

.loading {
  text-align: center;
  padding: 2rem;
  color: var(--text-secondary);
}

.spinner {
  display: inline-block;
  width: 24px;
  height: 24px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.section-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  margin-top: 0.5rem;
}

.announcement {
  background: #fff3e0;
  border: 2px solid #ff9800;
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  margin-bottom: 1rem;
  position: relative;
}

.announcement-title {
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 0.25rem;
}

.announcement-message {
  font-size: 0.95rem;
  color: var(--text);
}

.announcement-dismiss {
  position: absolute;
  top: 0.5rem;
  right: 0.75rem;
  background: none;
  border: none;
  font-size: 1.3rem;
  cursor: pointer;
  color: var(--text-secondary);
  padding: 0;
  line-height: 1;
}

.announcement-dismiss:hover {
  color: var(--text);
}

.announcement-admin-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.75rem;
  margin-bottom: 0.5rem;
}

.announcement-admin-card .small {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.user-card {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 0.75rem;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 0.4rem;
  font-size: 0.9rem;
}

.user-card-name {
  font-weight: 600;
}

.user-card-meta {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.badge {
  display: inline-block;
  padding: 0.15rem 0.5rem;
  border-radius: 12px;
  font-size: 0.7rem;
  font-weight: 700;
  background: var(--primary);
  color: white;
}

.badge.admin {
  background: var(--warning);
}

@media (min-width: 481px) {
  #app {
    padding: 2rem;
  }
}