:root {
  --primary: #667eea;
  --primary-dark: #5a67d8;
  --primary-light: #ebf0ff;
  --accent: #764ba2;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  --radius: 10px;
  --radius-lg: 16px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
  --shadow-lg: 0 10px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.05);
  --transition: all 0.2s ease;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif; background: var(--gray-50); color: var(--gray-800); min-height: 100vh; line-height: 1.6; }

/* Login */
.login-page { display: flex; align-items: center; justify-content: center; min-height: 100vh; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
.login-box { background: #fff; padding: 48px 40px; border-radius: var(--radius-lg); box-shadow: var(--shadow-lg); width: 380px; text-align: center; }
.login-logo { margin-bottom: 16px; }
.login-box h1 { font-size: 24px; font-weight: 700; color: var(--gray-900); margin-bottom: 4px; }
.login-subtitle { color: var(--gray-400); font-size: 14px; margin-bottom: 28px; }
.login-box .error { color: var(--danger); font-size: 13px; margin-bottom: 12px; display: none; background: #fef2f2; padding: 8px 12px; border-radius: 6px; }
.input-group { position: relative; margin-bottom: 16px; }
.input-group svg { position: absolute; left: 14px; top: 50%; transform: translateY(-50%); }
.input-group input { width: 100%; padding: 12px 14px 12px 42px; border: 1.5px solid var(--gray-200); border-radius: 8px; font-size: 15px; transition: var(--transition); background: var(--gray-50); }
.input-group input:focus { outline: none; border-color: var(--primary); background: #fff; box-shadow: 0 0 0 3px rgba(102,126,234,0.1); }
.login-btn { width: 100%; padding: 12px; background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; border: none; border-radius: 8px; font-size: 16px; font-weight: 500; cursor: pointer; transition: var(--transition); margin-top: 8px; }
.login-btn:hover { transform: translateY(-1px); box-shadow: 0 4px 12px rgba(102,126,234,0.4); }

/* Header */
.app-header { background: #fff; padding: 0 24px; height: 60px; box-shadow: var(--shadow-sm); display: flex; align-items: center; justify-content: space-between; position: sticky; top: 0; z-index: 100; border-bottom: 1px solid var(--gray-100); }
.header-left { display: flex; align-items: center; gap: 12px; }
.header-logo { display: flex; }
.app-header h1 { font-size: 17px; font-weight: 600; background: linear-gradient(135deg, #667eea, #764ba2); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.user-info { display: flex; align-items: center; gap: 10px; font-size: 14px; }
.user-avatar { width: 32px; height: 32px; border-radius: 50%; background: linear-gradient(135deg, #667eea, #764ba2); display: flex; align-items: center; justify-content: center; color: #fff; font-size: 13px; font-weight: 600; }
.role-badge { background: var(--primary-light); color: var(--primary); padding: 3px 10px; border-radius: 12px; font-size: 12px; font-weight: 500; }
.role-badge.supervisor { background: #fef3c7; color: #d97706; }

/* Layout */
.app-body { display: flex; min-height: calc(100vh - 60px); }
.sidebar { width: 220px; background: #fff; border-right: 1px solid var(--gray-100); padding: 16px 12px; flex-shrink: 0; }
.nav-item { display: flex; align-items: center; gap: 10px; padding: 10px 14px; border-radius: 8px; cursor: pointer; font-size: 14px; color: var(--gray-600); transition: var(--transition); margin-bottom: 2px; }
.nav-item:hover { background: var(--gray-100); color: var(--gray-800); }
.nav-item.active { background: var(--primary-light); color: var(--primary); font-weight: 500; }
.nav-item svg { flex-shrink: 0; }
.nav-divider { height: 1px; background: var(--gray-100); margin: 12px 8px; }
.main-content { flex: 1; padding: 28px 32px; max-width: 900px; overflow-y: auto; }

/* Page Header */
.page-header { margin-bottom: 20px; }
.page-header h2 { font-size: 22px; font-weight: 700; color: var(--gray-900); }
.page-desc { color: var(--gray-400); font-size: 13px; margin-top: 4px; }

/* Cards */
.card { background: #fff; border-radius: var(--radius-lg); padding: 24px; box-shadow: var(--shadow); margin-bottom: 20px; border: 1px solid var(--gray-100); }
.card-title { font-size: 15px; font-weight: 600; color: var(--gray-700); margin-bottom: 12px; }

/* Buttons */
.btn { padding: 9px 18px; border: none; border-radius: 8px; cursor: pointer; font-size: 14px; font-weight: 500; transition: var(--transition); display: inline-flex; align-items: center; gap: 6px; }
.btn-primary { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; }
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 4px 12px rgba(102,126,234,0.3); }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { background: #059669; }
.btn-danger { background: #fff; color: var(--danger); border: 1px solid var(--danger); }
.btn-danger:hover { background: #fef2f2; }
.btn-ghost { background: transparent; color: var(--gray-600); border: 1px solid var(--gray-200); }
.btn-ghost:hover { background: var(--gray-100); border-color: var(--gray-300); }
.btn-sm { padding: 6px 12px; font-size: 13px; }
.btn-round { border-radius: 20px; }

/* Forms */
.form-group { margin-bottom: 18px; }
.form-group label { display: block; font-size: 13px; font-weight: 600; color: var(--gray-600); margin-bottom: 6px; text-transform: uppercase; letter-spacing: 0.3px; }
.form-group input, .form-group select { width: 100%; padding: 10px 14px; border: 1.5px solid var(--gray-200); border-radius: 8px; font-size: 14px; transition: var(--transition); background: var(--gray-50); }
.form-group input:focus, .form-group select:focus { outline: none; border-color: var(--primary); background: #fff; box-shadow: 0 0 0 3px rgba(102,126,234,0.1); }
.form-row { display: flex; gap: 12px; }
textarea { width: 100%; border: 1.5px solid var(--gray-200); border-radius: 8px; padding: 12px 14px; font-size: 14px; font-family: inherit; resize: vertical; transition: var(--transition); background: var(--gray-50); }
textarea:focus { outline: none; border-color: var(--primary); background: #fff; box-shadow: 0 0 0 3px rgba(102,126,234,0.1); }
.input-sm { padding: 8px 12px; border: 1.5px solid var(--gray-200); border-radius: 8px; font-size: 14px; background: var(--gray-50); }
.input-sm:focus { outline: none; border-color: var(--primary); }
.add-form { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-bottom: 16px; }

/* Search */
.search-bar { display: flex; gap: 8px; margin-bottom: 16px; align-items: center; }
.search-input-wrap { flex: 1; position: relative; }
.search-input-wrap svg { position: absolute; left: 12px; top: 50%; transform: translateY(-50%); }
.search-input-wrap input { width: 100%; padding: 10px 14px 10px 38px; border: 1.5px solid var(--gray-200); border-radius: 8px; font-size: 14px; background: var(--gray-50); transition: var(--transition); }
.search-input-wrap input:focus { outline: none; border-color: var(--primary); background: #fff; box-shadow: 0 0 0 3px rgba(102,126,234,0.1); }

/* Student chips */
.student-list { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 16px; }
.student-chip { padding: 6px 14px; border-radius: 20px; background: var(--gray-100); cursor: pointer; font-size: 13px; border: 1.5px solid var(--gray-200); transition: var(--transition); font-weight: 500; }
.student-chip:hover { border-color: var(--primary); color: var(--primary); }
.student-chip.active { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; border-color: transparent; }

/* Record list */
.record-list { list-style: none; }
.record-item { padding: 16px 0; border-bottom: 1px solid var(--gray-100); display: flex; align-items: center; justify-content: space-between; cursor: pointer; transition: var(--transition); border-radius: 8px; }
.record-item:hover { background: var(--gray-50); margin: 0 -16px; padding: 16px; }
.record-item:last-child { border-bottom: none; }
.record-item .info { flex: 1; }
.record-item .title { font-size: 15px; font-weight: 600; color: var(--gray-800); }
.record-item .meta { font-size: 12px; color: var(--gray-400); margin-top: 4px; }
.record-item .status-tags { display: flex; gap: 6px; margin-top: 6px; }
.list-subtitle { font-size: 13px; color: var(--gray-400); font-weight: 500; margin-bottom: 8px; }
.empty-state { color: var(--gray-400); padding: 40px 0; text-align: center; font-size: 14px; }

/* Tags */
.tag { font-size: 11px; padding: 3px 8px; border-radius: 12px; font-weight: 500; }
.tag-comment { background: #fef3c7; color: #d97706; }
.tag-summary { background: #d1fae5; color: #059669; }
.tag-student { background: var(--primary-light); color: var(--primary); }

/* Detail */
.detail-header { display: flex; align-items: center; gap: 12px; margin-bottom: 20px; }
.back-btn { width: 36px; height: 36px; border-radius: 8px; border: 1px solid var(--gray-200); background: #fff; cursor: pointer; display: flex; align-items: center; justify-content: center; transition: var(--transition); }
.back-btn:hover { background: var(--gray-100); border-color: var(--primary); color: var(--primary); }
.detail-header h2 { font-size: 20px; font-weight: 700; }
.detail-meta { font-size: 13px; color: var(--gray-400); margin-bottom: 20px; padding-bottom: 16px; border-bottom: 1px solid var(--gray-100); }
.detail-actions { margin-top: 24px; padding-top: 16px; border-top: 1px solid var(--gray-100); display: flex; gap: 10px; }

/* Preview table */
.preview-table { width: 100%; border-collapse: collapse; margin: 16px 0; border-radius: 8px; overflow: hidden; border: 1px solid var(--gray-200); }
.preview-table th, .preview-table td { border: 1px solid var(--gray-200); padding: 10px 14px; text-align: left; font-size: 14px; }
.preview-table th { background: var(--gray-50); width: 140px; font-weight: 600; color: var(--gray-600); }
.preview-table .section-header { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; font-weight: 600; text-align: center; font-size: 14px; }
.preview-table .highlight-header { background: linear-gradient(135deg, #f59e0b, #ef4444); color: #fff; font-weight: 600; text-align: center; }

/* Comments */
.comment-section { margin-top: 24px; padding-top: 20px; border-top: 1px solid var(--gray-100); }
.comment-section h3 { font-size: 15px; margin-bottom: 12px; display: flex; align-items: center; gap: 8px; color: var(--gray-700); }
.comment-box { background: var(--gray-50); border-radius: 8px; padding: 16px; margin-bottom: 10px; white-space: pre-wrap; font-size: 14px; line-height: 1.7; min-height: 44px; border: 1px solid var(--gray-100); }
.comment-box.empty { color: var(--gray-400); font-style: italic; }

/* AI Chat */
.ai-chat { border: 1.5px solid var(--gray-200); border-radius: var(--radius-lg); margin-top: 12px; display: flex; flex-direction: column; height: 480px; overflow: hidden; background: var(--gray-50); }
.ai-messages { flex: 1; overflow-y: auto; padding: 20px; scroll-behavior: smooth; }
.ai-msg { margin-bottom: 16px; padding: 14px 18px; border-radius: 16px; font-size: 14px; line-height: 1.7; white-space: pre-wrap; max-width: 82%; word-break: break-word; animation: fadeIn 0.3s ease; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }
.ai-msg.user { background: linear-gradient(135deg, #667eea, #764ba2); color: #fff; margin-left: auto; border-bottom-right-radius: 4px; }
.ai-msg.assistant { background: #fff; margin-right: auto; border-bottom-left-radius: 4px; box-shadow: var(--shadow-sm); border: 1px solid var(--gray-100); }
.ai-msg.system-hint { background: #fffbeb; color: #92400e; font-size: 12px; text-align: center; margin: 8px auto; max-width: 90%; padding: 8px 14px; border-radius: 8px; }
.ai-msg .save-btn { margin-top: 10px; font-size: 12px; cursor: pointer; color: var(--primary); display: inline-flex; align-items: center; gap: 4px; padding: 4px 10px; border: 1px solid var(--primary); border-radius: 6px; transition: var(--transition); }
.ai-msg .save-btn:hover { background: var(--primary-light); }
.ai-msg .typing { color: var(--gray-400); }
.ai-input { display: flex; gap: 8px; padding: 14px 16px; border-top: 1px solid var(--gray-200); background: #fff; }
.ai-input input { flex: 1; padding: 10px 16px; border: 1.5px solid var(--gray-200); border-radius: 24px; font-size: 14px; outline: none; transition: var(--transition); }
.ai-input input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(102,126,234,0.1); }

/* Insights */
.insight-list { list-style: none; }
.insight-item { padding: 14px 0; border-bottom: 1px solid var(--gray-100); display: flex; justify-content: space-between; align-items: flex-start; gap: 12px; }
.insight-item:last-child { border-bottom: none; }
.insight-item .content { flex: 1; font-size: 14px; line-height: 1.6; white-space: pre-wrap; }

/* Import */
.import-row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.file-input { font-size: 13px; }
.import-result { margin-top: 10px; font-size: 13px; }
.hint-text { font-size: 13px; color: var(--gray-400); margin-bottom: 12px; }

/* Utilities */
.hidden { display: none !important; }

/* Responsive */
@media (max-width: 768px) {
  .sidebar { display: none; }
  .main-content { padding: 16px; }
  .app-header { padding: 0 16px; }
  .card { padding: 16px; }
  .ai-msg { max-width: 92%; }
}

/* Print */
@media print {
  .app-header, .sidebar, .btn, textarea, .no-print, .ai-chat, .search-bar, .student-list, .detail-actions { display: none !important; }
  .app-body { display: block; }
  .main-content { margin: 0; padding: 0; max-width: 100%; }
  .card { box-shadow: none; border: none; padding: 10px 0; }
  .preview-table th, .preview-table td { font-size: 12px; padding: 6px 8px; }
}