:root {
  --bg: #f0f2f5;
  --surface: #fff;
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-light: #eef2ff;
  --danger: #dc2626;
  --danger-hover: #b91c1c;
  --success: #16a34a;
  --warning: #f59e0b;
  --text: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,.06),0 1px 2px rgba(0,0,0,.04);
  --shadow-lg: 0 4px 14px rgba(0,0,0,.08);
  --sidebar-w: 240px;
  --header-h: 56px;
  --font: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Noto Sans SC",sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: var(--font); background: var(--bg); color: var(--text); min-height: 100vh; }

/* ===== Login ===== */
.login-page { display: flex; align-items: center; justify-content: center; min-height: 100vh; background: linear-gradient(135deg, #1e1b4b, #312e81, #4f46e5); }
.login-card { background: var(--surface); border-radius: 16px; padding: 40px; width: 400px; max-width: 90vw; box-shadow: 0 25px 50px rgba(0,0,0,.25); }
.login-card h1 { font-size: 24px; text-align: center; margin-bottom: 4px; }
.login-card .subtitle { text-align: center; color: var(--text-secondary); font-size: 13px; margin-bottom: 24px; }
.login-card .form-group { margin-bottom: 16px; }
.login-card label { display: block; font-size: 13px; font-weight: 600; margin-bottom: 6px; color: var(--text); }
.login-card input { width: 100%; padding: 10px 14px; border: 1.5px solid var(--border); border-radius: var(--radius); font-size: 14px; font-family: var(--font); transition: border-color .2s; }
.login-card input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-light); }
.login-card .btn-login { width: 100%; padding: 11px; background: var(--primary); color: #fff; border: none; border-radius: var(--radius); font-size: 15px; font-weight: 600; cursor: pointer; transition: .2s; }
.login-card .btn-login:hover { background: var(--primary-hover); }
.login-card .error-msg { color: var(--danger); font-size: 13px; text-align: center; margin-top: 8px; min-height: 20px; }

/* ===== Layout ===== */
.admin-layout { display: flex; min-height: 100vh; }
.sidebar { width: var(--sidebar-w); background: #1e1b4b; color: #fff; position: fixed; top: 0; left: 0; bottom: 0; z-index: 100; display: flex; flex-direction: column; }
.sidebar-brand { padding: 18px 20px; font-size: 18px; font-weight: 700; border-bottom: 1px solid rgba(255,255,255,.1); display: flex; align-items: center; gap: 10px; }
.sidebar-brand .icon { width: 32px; height: 32px; background: var(--primary); border-radius: 8px; display: flex; align-items: center; justify-content: center; font-size: 16px; }
.sidebar-nav { flex: 1; padding: 12px 0; }
.sidebar-nav a { display: flex; align-items: center; gap: 10px; padding: 10px 20px; color: rgba(255,255,255,.65); text-decoration: none; font-size: 14px; transition: .2s; border-left: 3px solid transparent; }
.sidebar-nav a:hover { color: #fff; background: rgba(255,255,255,.06); }
.sidebar-nav a.active { color: #fff; background: rgba(255,255,255,.1); border-left-color: var(--primary); }
.sidebar-nav a .nav-icon { width: 20px; text-align: center; font-size: 15px; }
.sidebar-footer { padding: 12px 20px; border-top: 1px solid rgba(255,255,255,.1); font-size: 13px; color: rgba(255,255,255,.5); }
.sidebar-footer .user-info { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; }
.sidebar-footer .user-avatar { width: 28px; height: 28px; border-radius: 50%; background: var(--primary); display: flex; align-items: center; justify-content: center; font-size: 12px; font-weight: 600; }
.sidebar-footer .btn-logout { width: 100%; padding: 7px; background: rgba(255,255,255,.1); color: #fff; border: none; border-radius: 6px; font-size: 12px; cursor: pointer; transition: .2s; }
.sidebar-footer .btn-logout:hover { background: rgba(255,255,255,.2); }

.main-content { margin-left: var(--sidebar-w); flex: 1; min-height: 100vh; }
.topbar { background: var(--surface); height: var(--header-h); border-bottom: 1px solid var(--border); display: flex; align-items: center; padding: 0 24px; position: sticky; top: 0; z-index: 50; }
.topbar h2 { font-size: 17px; font-weight: 600; }
.page-body { padding: 24px; max-width: 1400px; }

/* ===== Cards ===== */
.card { background: var(--surface); border-radius: var(--radius); box-shadow: var(--shadow); margin-bottom: 20px; }
.card-header { padding: 16px 20px; border-bottom: 1px solid var(--border); display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 12px; }
.card-header h3 { font-size: 15px; font-weight: 600; }
.card-body { padding: 20px; }
.card-body.no-pad { padding: 0; }

/* ===== Stats Grid ===== */
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; margin-bottom: 20px; }
.stat-card { background: var(--surface); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.stat-card .stat-icon { width: 40px; height: 40px; border-radius: 10px; display: flex; align-items: center; justify-content: center; font-size: 18px; margin-bottom: 12px; }
.stat-card .stat-value { font-size: 28px; font-weight: 700; }
.stat-card .stat-label { font-size: 13px; color: var(--text-secondary); margin-top: 4px; }

/* ===== Buttons ===== */
.btn { display: inline-flex; align-items: center; gap: 6px; padding: 8px 16px; border-radius: var(--radius); font-size: 13px; font-weight: 600; cursor: pointer; border: 1.5px solid transparent; font-family: var(--font); transition: .2s; white-space: nowrap; }
.btn-primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn-primary:hover { background: var(--primary-hover); }
.btn-outline { background: transparent; color: var(--text); border-color: var(--border); }
.btn-outline:hover { background: var(--bg); }
.btn-danger { background: var(--danger); color: #fff; border-color: var(--danger); }
.btn-danger:hover { background: var(--danger-hover); }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { background: #15803d; }
.btn-sm { padding: 5px 10px; font-size: 12px; }
.btn-xs { padding: 3px 8px; font-size: 11px; }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn-group { display: flex; gap: 8px; flex-wrap: wrap; }

/* ===== Forms ===== */
.form-group { margin-bottom: 14px; }
.form-group label { display: block; font-size: 13px; font-weight: 600; margin-bottom: 5px; }
.form-group input, .form-group select, .form-group textarea { width: 100%; padding: 8px 12px; border: 1.5px solid var(--border); border-radius: 6px; font-size: 13px; font-family: var(--font); transition: .2s; }
.form-group input:focus, .form-group select:focus, .form-group textarea:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-light); }
.form-group textarea { resize: vertical; min-height: 80px; }
.form-inline { display: flex; gap: 10px; align-items: flex-end; flex-wrap: wrap; }
.form-inline .form-group { margin-bottom: 0; }

/* ===== Tables ===== */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: 13px; }
th { background: #f8fafc; padding: 10px 14px; text-align: left; font-weight: 600; border-bottom: 2px solid var(--border); white-space: nowrap; font-size: 12px; color: var(--text-secondary); text-transform: uppercase; letter-spacing: .3px; }
td { padding: 10px 14px; border-bottom: 1px solid var(--border); }
tr:hover td { background: #f8fafc; }
tr.selected td { background: var(--primary-light); }
.check-col { width: 40px; text-align: center; }
.check-col input { width: 16px; height: 16px; cursor: pointer; }

/* ===== Badges ===== */
.badge { display: inline-block; padding: 3px 10px; border-radius: 20px; font-size: 11px; font-weight: 600; }
.badge-admin { background: #fef2f2; color: var(--danger); }
.badge-librarian { background: #fefce8; color: #a16207; }
.badge-user { background: #f0fdf4; color: var(--success); }
.badge-borrowed { background: #eff6ff; color: #2563eb; }
.badge-overdue { background: #fef2f2; color: var(--danger); }
.badge-returned { background: #f0fdf4; color: var(--success); }

/* ===== Pagination ===== */
.pagination { display: flex; align-items: center; justify-content: center; gap: 6px; padding: 16px 0; }
.pagination button { padding: 6px 12px; border: 1px solid var(--border); border-radius: 6px; background: var(--surface); cursor: pointer; font-size: 13px; font-family: var(--font); transition: .2s; }
.pagination button:hover:not(:disabled) { background: var(--bg); }
.pagination button:disabled { opacity: .4; cursor: not-allowed; }
.pagination button.active { background: var(--primary); color: #fff; border-color: var(--primary); }
.pagination .page-info { font-size: 13px; color: var(--text-secondary); margin: 0 8px; }

/* ===== Modal ===== */
.modal-overlay { position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 200; display: flex; align-items: center; justify-content: center; padding: 20px; }
.modal { background: var(--surface); border-radius: 12px; width: 560px; max-width: 95vw; max-height: 80vh; overflow-y: auto; box-shadow: var(--shadow-lg); }
.modal-header { padding: 16px 20px; border-bottom: 1px solid var(--border); display: flex; align-items: center; justify-content: space-between; }
.modal-header h3 { font-size: 16px; }
.modal-close { background: none; border: none; font-size: 20px; cursor: pointer; color: var(--text-secondary); padding: 4px; line-height: 1; }
.modal-body { padding: 20px; }
.modal-footer { padding: 12px 20px; border-top: 1px solid var(--border); display: flex; justify-content: flex-end; gap: 8px; }

/* ===== Toast ===== */
.toast-container { position: fixed; top: 20px; right: 20px; z-index: 300; display: flex; flex-direction: column; gap: 8px; }
.toast { padding: 12px 20px; border-radius: var(--radius); color: #fff; font-size: 13px; font-weight: 500; box-shadow: var(--shadow-lg); animation: slideIn .3s ease; max-width: 380px; }
.toast-success { background: var(--success); }
.toast-error { background: var(--danger); }
.toast-warning { background: var(--warning); color: #1e293b; }
@keyframes slideIn { from { transform: translateX(100%); opacity: 0; } to { transform: translateX(0); opacity: 1; } }

/* ===== Toolbar ===== */
.toolbar { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 10px; margin-bottom: 16px; }
.toolbar-left { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.toolbar-right { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.search-input { padding: 7px 12px; border: 1.5px solid var(--border); border-radius: 6px; font-size: 13px; font-family: var(--font); width: 240px; }
.search-input:focus { outline: none; border-color: var(--primary); }
.batch-bar { background: var(--primary-light); border: 1px solid var(--primary); border-radius: var(--radius); padding: 10px 16px; margin-bottom: 16px; display: none; align-items: center; gap: 12px; flex-wrap: wrap; }
.batch-bar.show { display: flex; }
.batch-bar .batch-count { font-size: 13px; font-weight: 600; color: var(--primary); }

/* ===== Empty State ===== */
.empty { text-align: center; padding: 40px 20px; color: var(--text-secondary); }
.empty .empty-icon { font-size: 40px; margin-bottom: 12px; }

/* ===== Loading ===== */
.loading { text-align: center; padding: 40px 20px; 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 .7s linear infinite; margin-bottom: 8px; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); transition: .3s; }
  .sidebar.open { transform: translateX(0); }
  .main-content { margin-left: 0; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .search-input { width: 160px; }
}

/* ===== File Input ===== */
.file-input-wrap { position: relative; display: inline-block; }
.file-input-wrap input[type="file"] { position: absolute; opacity: 0; width: 100%; height: 100%; cursor: pointer; }

/* ===== Select All ===== */
.select-all-label { display: flex; align-items: center; gap: 6px; font-size: 12px; color: var(--text-secondary); cursor: pointer; }