/* =========================================
   CSS Variables & Base Styles
   ========================================= */
/* 本地字体加载，fonts.gstatic.com 在国内容器访问不稳定 */
@font-face {
  font-family: 'Noto Sans SC';
  src: url('../fonts/noto-sans-sc-300.woff2') format('woff2');
  font-weight: 300;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Noto Sans SC';
  src: url('../fonts/noto-sans-sc-400.woff2') format('woff2');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Noto Sans SC';
  src: url('../fonts/noto-sans-sc-500.woff2') format('woff2');
  font-weight: 500;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Noto Sans SC';
  src: url('../fonts/noto-sans-sc-700.woff2') format('woff2');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
}

:root {
  --bg: #0D0B1E;
  --surface: #1A1830;
  --surface2: #232040;
  --orange: #FF9800;
  --orange-hover: #FB8C00;
  --blue: #3F51B5;
  --blue-hover: #303F9F;
  --green: #4CAF50;
  --red: #F44336;
  --dim: #6B6B8D;
  --outline: rgba(255,255,255,0.08);
  --text: #FFFFFF;
  --text-secondary: #B0B0C8;
  --border: rgba(255,255,255,0.08);
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
  --radius: 8px;
  --sidebar-width: 220px;
  --transition: 0.2s ease;
}

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

body {
  font-family: 'Noto Sans SC', sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  line-height: 1.6;
  min-height: 100vh;
}

/* =========================================
   Layout
   ========================================= */
.app-layout {
  display: flex;
  min-height: 100vh;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  transition: transform var(--transition);
}

.sidebar-header {
  padding: 20px 16px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 12px;
}

.sidebar-logo {
  width: 36px;
  height: 36px;
  background: var(--orange);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  flex-shrink: 0;
}

.sidebar-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--text);
  line-height: 1.3;
}

.sidebar-subtitle {
  font-size: 11px;
  color: var(--dim);
}

.sidebar-nav {
  flex: 1;
  padding: 12px 0;
  overflow-y: auto;
}

.nav-section {
  margin-bottom: 8px;
}

.nav-label {
  padding: 8px 16px 4px;
  font-size: 11px;
  color: var(--dim);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 14px;
  cursor: pointer;
  transition: all var(--transition);
  border-left: 3px solid transparent;
}

.nav-item:hover {
  background: var(--outline);
  color: var(--text);
}

.nav-item.active {
  background: rgba(255,152,0,0.1);
  color: var(--orange);
  border-left-color: var(--orange);
}

.nav-item i {
  font-size: 18px;
  width: 20px;
  text-align: center;
}

/* Main Content */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Top Bar */
.topbar {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 50;
}

.topbar-title {
  font-size: 16px;
  font-weight: 600;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Page Container */
.page {
  padding: 24px;
  flex: 1;
}

.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.page-title {
  font-size: 20px;
  font-weight: 700;
}

/* =========================================
   Buttons
   ========================================= */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
  font-family: inherit;
  text-decoration: none;
}

.btn-primary {
  background: var(--orange);
  color: #fff;
}

.btn-primary:hover {
  background: var(--orange-hover);
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

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

.btn-danger {
  background: var(--red);
  color: #fff;
}

.btn-danger:hover {
  background: #d32f2f;
}

.btn-sm {
  padding: 5px 12px;
  font-size: 13px;
}

.btn-icon {
  padding: 7px;
  border-radius: 6px;
}

/* =========================================
   Form Elements
   ========================================= */
.form-group {
  margin-bottom: 16px;
}

.form-label {
  display: block;
  margin-bottom: 6px;
  font-size: 13px;
  color: var(--text-secondary);
  font-weight: 500;
}

.form-label .required {
  color: var(--red);
  margin-left: 2px;
}

.form-control {
  width: 100%;
  padding: 10px 14px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 14px;
  font-family: inherit;
  transition: border-color var(--transition);
  outline: none;
}

.form-control:focus {
  border-color: var(--orange);
}

.form-control::placeholder {
  color: var(--dim);
}

select.form-control {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%236B6B8D' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

/* =========================================
   Cards
   ========================================= */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.card-title {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--text);
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
}

.info-item {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.info-label {
  font-size: 12px;
  color: var(--dim);
}

.info-value {
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
}

/* =========================================
   Tables
   ========================================= */
.table-wrapper {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th, td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  background: var(--surface2);
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

tr:hover td {
  background: rgba(255,255,255,0.02);
}

td {
  font-size: 14px;
  color: var(--text);
}

/* Status Badge */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 500;
}

.badge-success {
  background: rgba(76,175,80,0.15);
  color: var(--green);
}

.badge-warning {
  background: rgba(255,152,0,0.15);
  color: var(--orange);
}

.badge-danger {
  background: rgba(244,67,54,0.15);
  color: var(--red);
}

.badge-info {
  background: rgba(63,81,181,0.15);
  color: var(--blue);
}

/* =========================================
   Pagination
   ========================================= */
.pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  padding: 16px 0;
}

.pagination button {
  min-width: 36px;
  height: 36px;
  padding: 0 10px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-secondary);
  font-size: 14px;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.pagination button:hover:not(:disabled) {
  background: var(--surface2);
  color: var(--text);
}

.pagination button.active {
  background: var(--orange);
  border-color: var(--orange);
  color: #fff;
}

.pagination button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.pagination .page-info {
  padding: 0 12px;
  color: var(--text-secondary);
  font-size: 13px;
}

/* =========================================
   Filter Bar
   ========================================= */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 20px;
  padding: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.filter-bar .form-control {
  width: auto;
  min-width: 160px;
}

.filter-bar .search-input {
  flex: 1;
  min-width: 200px;
}

.filter-bar .btn {
  white-space: nowrap;
}

/* =========================================
   Tabs
   ========================================= */
.tabs {
  display: flex;
  border-bottom: 1px solid var(--border);
  margin-bottom: 20px;
  gap: 4px;
}

.tab-btn {
  padding: 10px 20px;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.tab-btn:hover {
  color: var(--text);
}

.tab-btn.active {
  color: var(--orange);
  border-bottom-color: var(--orange);
}

.tab-panel {
  display: none;
}

.tab-panel.active {
  display: block;
}

/* =========================================
   Modal / Overlay
   ========================================= */
.modal-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0,0,0,0.6);
  z-index: 200;
  align-items: center;
  justify-content: center;
}

.modal-overlay.show {
  display: flex;
}

.modal {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  width: 90%;
  max-width: 600px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: var(--shadow);
}

.modal-header {
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-title {
  font-size: 16px;
  font-weight: 600;
}

.modal-close {
  background: transparent;
  border: none;
  color: var(--dim);
  font-size: 20px;
  cursor: pointer;
  padding: 4px;
  line-height: 1;
}

.modal-close:hover {
  color: var(--text);
}

.modal-body {
  padding: 20px;
}

.modal-footer {
  padding: 16px 20px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: flex-end;
  gap: 12px;
}

/* =========================================
   Avatar
   ========================================= */
.avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--orange);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  font-weight: 700;
  flex-shrink: 0;
}

.avatar-sm {
  width: 36px;
  height: 36px;
  font-size: 14px;
}

/* =========================================
   Dropdown Menu
   ========================================= */
.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-menu {
  display: none;
  position: absolute;
  right: 0;
  top: 100%;
  margin-top: 4px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-width: 140px;
  z-index: 150;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.dropdown-menu.show {
  display: block;
}

.dropdown-item {
  padding: 10px 16px;
  font-size: 14px;
  color: var(--text);
  cursor: pointer;
  transition: background var(--transition);
}

.dropdown-item:hover {
  background: var(--outline);
}

.dropdown-item.danger {
  color: var(--red);
}

/* =========================================
   Back Button
   ========================================= */
.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--text-secondary);
  font-size: 14px;
  cursor: pointer;
  margin-bottom: 16px;
  padding: 8px 0;
  transition: color var(--transition);
}

.back-btn:hover {
  color: var(--orange);
}

/* =========================================
   Empty State
   ========================================= */
.empty-state {
  text-align: center;
  padding: 48px 24px;
  color: var(--dim);
}

.empty-state i {
  font-size: 48px;
  margin-bottom: 16px;
  display: block;
}

.empty-state p {
  font-size: 14px;
}

/* =========================================
   Loading
   ========================================= */
.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px;
  color: var(--dim);
  font-size: 14px;
  gap: 10px;
}

.loading::before {
  content: '';
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-top-color: var(--orange);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

/* =========================================
   Toast
   ========================================= */
.toast-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toast {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  box-shadow: var(--shadow);
  animation: slideIn 0.3s ease;
  max-width: 320px;
}

.toast.success { border-left: 3px solid var(--green); }
.toast.error   { border-left: 3px solid var(--red); }
.toast.info    { border-left: 3px solid var(--blue); }

@keyframes slideIn {
  from { transform: translateX(100%); opacity: 0; }
  to   { transform: translateX(0); opacity: 1; }
}

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .filter-bar {
    flex-direction: column;
  }

  .filter-bar .form-control,
  .filter-bar .search-input {
    width: 100%;
  }

  .topbar {
    padding: 0 16px;
  }

  .page {
    padding: 16px;
  }

  .page-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }
}

/* =========================================
   Page Header with Back
   ========================================= */
.page-header-with-back {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 24px;
}

.page-header-with-back .page-title {
  flex: 1;
}

/* =========================================
   Form Section Title
   ========================================= */
.form-section {
  margin-bottom: 24px;
}

.form-section-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--orange);
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

/* Dynamic parent rows */
.parent-row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr auto;
  gap: 12px;
  align-items: end;
  margin-bottom: 12px;
}

.parent-row .btn-remove {
  background: transparent;
  border: 1px solid var(--red);
  color: var(--red);
  padding: 10px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
}

.parent-row .btn-remove:hover {
  background: var(--red);
  color: #fff;
}

/* Action buttons in table */
.action-group {
  display: flex;
  gap: 6px;
  align-items: center;
}
/* 学生列表专用样式 */
input[type="checkbox"] {
  width: 16px;
  height: 16px;
  cursor: pointer;
  accent-color: var(--primary);
}

.sort-icon {
  font-size: 11px;
  color: var(--dim);
  margin-left: 2px;
}

/* 低课时警告 */
.badge-warning {
  background: rgba(255, 183, 0, 0.15);
  color: #FFB700;
  border: 1px solid rgba(255, 183, 0, 0.3);
}
.badge-danger {
  background: rgba(255, 82, 82, 0.15);
  color: #FF5252;
  border: 1px solid rgba(255, 82, 82, 0.3);
}
/* 详情页课时颜色 */
.hours-highlight { color: var(--orange); }
.hours-warning { color: #FFB700; }
.hours-danger { color: #FF5252; }

/* 详情页头像 */
.avatar { border-radius: 50%; background: var(--primary); color: #fff; display:flex; align-items:center; justify-content:center; font-weight:700; flex-shrink:0; }

/* 详情页家长信息行 */
.parent-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  background: var(--bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.avatar-sm {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 700;
  flex-shrink: 0;
}

/* 家长信息卡片 */
.parent-card {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.parent-card-left {
  flex-shrink: 0;
}
.parent-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  font-weight: 700;
}
.parent-card-body {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
}
.parent-relation {
  font-size: 12px;
  color: var(--dim);
  line-height: 1.4;
}
.parent-name {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
}
.parent-phone {
  font-size: 13px;
  color: var(--text);
  margin-top: 2px;
}