/* =====================================================
   LMS SaaS Platform — Professional UI
   ===================================================== */

/* =================== VARIABLES =================== */
:root {
    --primary:        #2563eb;
    --primary-dark:   #1d4ed8;
    --primary-light:  rgba(37,99,235,0.12);
    --sidebar-bg:     #0f172a;
    --sidebar-width:  256px;
    --header-h:       60px;
    --radius:         10px;
    --radius-sm:      6px;
    --card-bg:        #ffffff;
    --page-bg:        #f1f5f9;
    --border:         #e2e8f0;
    --text:           #0f172a;
    --text-muted:     #64748b;
    --success:        #16a34a;
    --danger:         #dc2626;
    --warning:        #d97706;
    --shadow-sm:      0 1px 3px rgba(0,0,0,0.08);
    --shadow:         0 4px 16px rgba(0,0,0,0.10);
    --transition:     0.15s ease;
}

/* =================== RESET =================== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background: var(--page-bg);
    color: var(--text);
    font-size: 14px;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}
a { text-decoration: none; color: var(--primary); }
img { max-width: 100%; }

/* =================== APP LAYOUT =================== */
.app-wrapper { display: flex; min-height: 100vh; }

/* =================== SIDEBAR =================== */
.sidebar {
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    position: fixed;
    inset: 0 auto 0 0;
    display: flex;
    flex-direction: column;
    z-index: 1000;
    transition: transform var(--transition);
    overflow: hidden;
}

/* Scrollable nav area */
.sidebar-nav {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    padding: 8px 0 12px;
    scrollbar-width: thin;
    scrollbar-color: rgba(255,255,255,0.08) transparent;
}
.sidebar-nav::-webkit-scrollbar { width: 3px; }
.sidebar-nav::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.08); border-radius: 4px; }

/* Logo / header */
.sidebar-header {
    height: var(--header-h);
    display: flex;
    align-items: center;
    padding: 0 16px;
    border-bottom: 1px solid rgba(255,255,255,0.06);
    flex-shrink: 0;
}
.sidebar-header .logo {
    display: flex;
    align-items: center;
    gap: 10px;
    color: #fff;
    font-size: 16px;
    font-weight: 700;
    letter-spacing: -0.3px;
    white-space: nowrap;
}
.sidebar-header .logo i {
    width: 34px; height: 34px;
    background: var(--primary);
    border-radius: 8px;
    display: flex; align-items: center; justify-content: center;
    font-size: 16px;
    flex-shrink: 0;
}

/* Section headings */
.nav-section {
    padding: 20px 16px 4px;
    font-size: 10px;
    font-weight: 700;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: rgba(255,255,255,0.25);
    user-select: none;
}
.nav-section-label {
    padding: 12px 16px 2px;
    font-size: 9.5px;
    font-weight: 700;
    letter-spacing: 0.8px;
    text-transform: uppercase;
    color: rgba(255,255,255,0.16);
    user-select: none;
}

/* Nav links */
.nav-link {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 16px;
    margin: 1px 8px;
    border-radius: var(--radius-sm);
    color: rgba(255,255,255,0.6);
    font-size: 13px;
    font-weight: 400;
    transition: background var(--transition), color var(--transition);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    cursor: pointer;
}
.nav-link i {
    width: 16px;
    font-size: 13px;
    text-align: center;
    flex-shrink: 0;
    opacity: 0.75;
    transition: opacity var(--transition);
}
.nav-link:hover {
    background: rgba(255,255,255,0.07);
    color: rgba(255,255,255,0.9);
}
.nav-link:hover i { opacity: 1; }
.nav-link.active {
    background: var(--primary-light);
    color: #60a5fa;
    font-weight: 500;
}
.nav-link.active i { color: #60a5fa; opacity: 1; }

/* Sidebar footer */
.sidebar-footer {
    border-top: 1px solid rgba(255,255,255,0.06);
    padding: 8px 0;
    flex-shrink: 0;
}
.sidebar-footer .nav-link { font-size: 12.5px; margin: 1px 8px; }
.sidebar-footer .nav-link[href*="logout"] { color: rgba(248,113,113,0.7); }
.sidebar-footer .nav-link[href*="logout"]:hover {
    background: rgba(239,68,68,0.1);
    color: #f87171;
}

/* Overlay (mobile) */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 999;
    backdrop-filter: blur(2px);
}
.sidebar-overlay.show { display: block; }

/* =================== MAIN CONTENT =================== */
.main-content {
    margin-left: var(--sidebar-width);
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    min-width: 0;
}

/* =================== TOPBAR =================== */
.topbar {
    height: var(--header-h);
    background: var(--card-bg);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
    position: sticky;
    top: 0;
    z-index: 900;
    gap: 12px;
    box-shadow: var(--shadow-sm);
}

.topbar-left { display: flex; align-items: center; gap: 12px; min-width: 0; }

.menu-toggle {
    display: none;
    font-size: 20px;
    color: var(--text-muted);
    cursor: pointer;
    padding: 4px;
    border-radius: 6px;
    flex-shrink: 0;
    transition: color var(--transition);
}
.menu-toggle:hover { color: var(--text); }

.page-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.topbar-right {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}

/* Notification bell */
.topbar-icon-btn {
    position: relative;
    width: 36px; height: 36px;
    border-radius: 8px;
    display: flex; align-items: center; justify-content: center;
    color: var(--text-muted);
    font-size: 16px;
    cursor: pointer;
    transition: background var(--transition), color var(--transition);
}
.topbar-icon-btn:hover { background: var(--page-bg); color: var(--text); }
.badge-dot {
    position: absolute;
    top: 5px; right: 5px;
    background: var(--danger);
    color: #fff;
    font-size: 9px;
    font-weight: 700;
    border-radius: 10px;
    min-width: 14px; height: 14px;
    display: flex; align-items: center; justify-content: center;
    padding: 0 3px;
    border: 2px solid #fff;
}

/* User menu */
.user-menu {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    padding: 4px 8px 4px 4px;
    border-radius: 8px;
    transition: background var(--transition);
}
.user-menu:hover { background: var(--page-bg); }
.user-avatar {
    width: 34px; height: 34px;
    border-radius: 8px;
    background: var(--primary);
    color: #fff;
    display: flex; align-items: center; justify-content: center;
    font-weight: 700;
    font-size: 14px;
    flex-shrink: 0;
    overflow: hidden;
}
.user-avatar img { width: 100%; height: 100%; object-fit: cover; }
.user-info { line-height: 1.3; }
.user-info strong { display: block; font-size: 13px; font-weight: 600; color: var(--text); }
.user-info small { font-size: 11px; color: var(--text-muted); }

/* =================== PAGE CONTENT =================== */
.page-content { padding: 20px 24px; flex: 1; }

/* =================== CARDS =================== */
.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: var(--shadow-sm);
}
.card-title {
    font-size: 14px;
    font-weight: 600;
    margin: 0 0 14px;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 8px;
}
.card-title i { color: var(--primary); font-size: 14px; }

/* =================== STAT CARDS =================== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
    margin-bottom: 20px;
}
.stat-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    padding: 18px 20px;
    display: flex;
    align-items: center;
    gap: 14px;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), transform var(--transition);
    text-decoration: none;
    color: inherit;
}
.stat-card:hover { box-shadow: var(--shadow); transform: translateY(-1px); }
.stat-icon {
    width: 46px; height: 46px;
    border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
    font-size: 20px;
    color: #fff;
    flex-shrink: 0;
}
.stat-info h3 { font-size: 22px; font-weight: 700; line-height: 1; color: var(--text); }
.stat-info p { font-size: 12px; color: var(--text-muted); margin-top: 3px; }

/* =================== TABLES =================== */
.table-wrap { overflow-x: auto; border-radius: var(--radius-sm); }
table.data-table { width: 100%; border-collapse: collapse; font-size: 13px; }
table.data-table th {
    padding: 10px 14px;
    text-align: left;
    background: var(--page-bg);
    font-weight: 600;
    font-size: 11.5px;
    text-transform: uppercase;
    letter-spacing: 0.4px;
    color: var(--text-muted);
    border-bottom: 1px solid var(--border);
    white-space: nowrap;
}
table.data-table td {
    padding: 11px 14px;
    border-bottom: 1px solid var(--border);
    vertical-align: middle;
}
table.data-table tbody tr:last-child td { border-bottom: none; }
table.data-table tbody tr:hover td { background: #f8fafc; }

/* =================== BUTTONS =================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    border: 1px solid transparent;
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: opacity var(--transition), background var(--transition), box-shadow var(--transition);
    white-space: nowrap;
    line-height: 1;
}
.btn:hover { opacity: 0.88; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); opacity: 1; }
.btn-success { background: var(--success); color: #fff; }
.btn-danger  { background: var(--danger); color: #fff; }
.btn-warning { background: var(--warning); color: #fff; }
.btn-secondary {
    background: var(--card-bg);
    color: var(--text);
    border-color: var(--border);
}
.btn-secondary:hover { background: var(--page-bg); opacity: 1; }
.btn-sm { padding: 5px 11px; font-size: 12px; border-radius: 5px; }
.btn-lg { padding: 11px 22px; font-size: 14px; }
.w-100 { width: 100%; justify-content: center; }

/* =================== FORMS =================== */
.form-group { margin-bottom: 16px; }
.form-group label {
    display: block;
    margin-bottom: 5px;
    font-size: 13px;
    font-weight: 500;
    color: var(--text);
}
.form-control {
    width: 100%;
    padding: 9px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 13.5px;
    color: var(--text);
    background: #fff;
    transition: border-color var(--transition), box-shadow var(--transition);
    font-family: inherit;
}
.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
}
.form-control::placeholder { color: #94a3b8; }
textarea.form-control { resize: vertical; min-height: 80px; }
select.form-control { cursor: pointer; }
.form-row { display: flex; gap: 16px; flex-wrap: wrap; }
.form-row .form-group { flex: 1; min-width: 180px; }

/* =================== BADGES =================== */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 3px 9px;
    border-radius: 20px;
    font-size: 11px;
    font-weight: 600;
    line-height: 1.4;
}
.badge-success   { background: #dcfce7; color: #15803d; }
.badge-danger    { background: #fee2e2; color: #b91c1c; }
.badge-warning   { background: #fef3c7; color: #92400e; }
.badge-info      { background: #dbeafe; color: #1d4ed8; }
.badge-secondary { background: #f1f5f9; color: #475569; }

/* =================== ALERTS =================== */
.alert {
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    margin-bottom: 16px;
    font-size: 13.5px;
    display: flex;
    align-items: center;
    gap: 10px;
}
.alert-success { background: #dcfce7; color: #15803d; border: 1px solid #bbf7d0; }
.alert-danger   { background: #fee2e2; color: #b91c1c; border: 1px solid #fecaca; }
.alert-info     { background: #dbeafe; color: #1d4ed8; border: 1px solid #bfdbfe; }
.alert-warning  { background: #fef3c7; color: #92400e; border: 1px solid #fde68a; }

/* =================== FOOTER =================== */
.footer {
    text-align: center;
    padding: 14px 24px;
    font-size: 12px;
    color: var(--text-muted);
    border-top: 1px solid var(--border);
    background: var(--card-bg);
}

/* =================== AUTH PAGES =================== */
.auth-wrapper {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #1e40af 0%, #0f172a 100%);
    padding: 20px;
}
.auth-box {
    background: #fff;
    border-radius: 14px;
    padding: 36px;
    width: 100%;
    max-width: 420px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.2);
}
.auth-box .logo-area { text-align: center; margin-bottom: 24px; }
.auth-box .logo-area h2 { margin-top: 12px; font-size: 20px; color: var(--text); }
.auth-box h3 { text-align: center; margin-bottom: 22px; color: var(--text-muted); font-size: 14px; font-weight: 500; }

/* =================== MISC UTILITIES =================== */
.text-muted   { color: var(--text-muted) !important; }
.d-flex       { display: flex; }
.align-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-10 { gap: 10px; }
.mb-0   { margin-bottom: 0 !important; }
.mt-0   { margin-top: 0 !important; }

.progress { height: 6px; background: var(--border); border-radius: 4px; overflow: hidden; }
.progress-bar { height: 100%; background: var(--primary); border-radius: 4px; transition: width 0.4s; }

/* =================== MOBILE RESPONSIVE =================== */
@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
        box-shadow: none;
    }
    .sidebar.open {
        transform: translateX(0);
        box-shadow: 4px 0 24px rgba(0,0,0,0.25);
    }
    .main-content { margin-left: 0; }
    .menu-toggle { display: flex; }
}

@media (max-width: 768px) {
    .page-content { padding: 14px 14px; }
    .stats-grid { grid-template-columns: 1fr 1fr; gap: 10px; }
    .stat-card { padding: 14px; gap: 10px; }
    .stat-icon { width: 38px; height: 38px; font-size: 16px; }
    .stat-info h3 { font-size: 18px; }
    .topbar { padding: 0 14px; }
    .user-info { display: none; }
    .card { padding: 14px; }
    .form-row { flex-direction: column; gap: 0; }
    .form-row .form-group { min-width: unset; }
    table.data-table th, table.data-table td { padding: 8px 10px; }
}

@media (max-width: 480px) {
    .stats-grid { grid-template-columns: 1fr; }
    .auth-box { padding: 24px 18px; }
    .btn { padding: 7px 13px; font-size: 12px; }
}