/* ============================================================
   FILE: assets/css/style.css
   EduConnect Virtual Classroom - Complete Stylesheet
   ============================================================ */

/* ---- CSS Variables ---- */
:root {
    --primary: #1a3a8f;
    --primary-light: #e8eeff;
    --primary-dark: #0f2461;
    --secondary: #2952c8;
    --secondary-light: #edf1fc;
    --accent: #3b6ce7;
    --accent-light: #f0f4fd;
    --bg: #f3f5fa;
    --bg-card: #ffffff;
    --text: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --border: #dde3ef;
    --danger: #dc3545;
    --danger-light: #fef2f2;
    --success: #198754;
    --success-light: #ecfdf5;
    --warning: #e68a00;
    --warning-light: #fff8eb;
    --sidebar-width: 260px;
    --radius: 12px;
    --radius-sm: 8px;
    --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 10px 30px rgba(0,0,0,0.1);
    --transition: 0.2s ease;
    --font: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-heading: 'Plus Jakarta Sans', 'DM Sans', sans-serif;
}

/* ---- Reset & Base ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 15px; scroll-behavior: smooth; }
body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}
a { color: var(--primary); text-decoration: none; }
img { max-width: 100%; display: block; }
input, select, textarea, button { font-family: inherit; font-size: inherit; }

/* ---- App Layout ---- */
.app-layout { display: flex; min-height: 100vh; }
.main-content {
    flex: 1;
    margin-left: var(--sidebar-width);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}
.content-area { padding: 24px; flex: 1; }

/* ---- Sidebar ---- */
.sidebar {
    position: fixed; top: 0; left: 0; bottom: 0;
    width: var(--sidebar-width);
    background: #0d1b4a;
    color: #fff;
    display: flex;
    flex-direction: column;
    z-index: 1000;
    transition: transform var(--transition);
    overflow-y: auto;
}
.sidebar-header {
    padding: 20px 18px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}
.logo { display: flex; align-items: center; gap: 10px; }
.logo-icon {
    width: 36px; height: 36px;
    background: var(--secondary);
    border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
}
.logo-icon svg { width: 20px; height: 20px; color: #fff; }
.logo-text { font-family: var(--font-heading); font-weight: 700; font-size: 1.05rem; }
.sidebar-close { display: none; background: none; border: none; color: #fff; font-size: 24px; cursor: pointer; }

.sidebar-user {
    padding: 18px;
    display: flex; align-items: center; gap: 12px;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}
.user-avatar {
    width: 40px; height: 40px;
    border-radius: 10px;
    background: var(--primary);
    display: flex; align-items: center; justify-content: center;
    font-weight: 700; font-size: 1rem;
    color: #fff;
}
.user-info { display: flex; flex-direction: column; }
.user-name { font-weight: 600; font-size: 0.9rem; }
.user-role {
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    opacity: 0.7;
    padding: 2px 8px;
    border-radius: 4px;
    display: inline-block;
    width: fit-content;
    margin-top: 2px;
}
.user-role.admin { background: rgba(239,68,68,0.2); color: #fca5a5; }
.user-role.teacher { background: rgba(16,185,129,0.2); color: #6ee7b7; }
.user-role.student { background: rgba(59,130,246,0.2); color: #93c5fd; }

.sidebar-nav { padding: 12px 10px; flex: 1; }
.nav-group-label {
    font-size: 0.68rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: rgba(255,255,255,0.35);
    padding: 16px 12px 6px;
    font-weight: 600;
}
.nav-item {
    display: flex; align-items: center; gap: 10px;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    color: rgba(255,255,255,0.7);
    font-size: 0.88rem; font-weight: 500;
    transition: all var(--transition);
    margin-bottom: 2px;
    cursor: pointer;
    border: none; background: none; width: 100%;
    text-align: left;
}
.nav-item svg { width: 18px; height: 18px; flex-shrink: 0; }
.nav-item:hover { background: rgba(255,255,255,0.1); color: #fff; }
.nav-item.active { background: rgba(255,255,255,0.15); color: #fff; font-weight: 600; }
.badge-pro {
    margin-left: auto;
    background: var(--accent);
    color: #000;
    font-size: 0.6rem;
    font-weight: 700;
    padding: 2px 6px;
    border-radius: 4px;
    text-transform: uppercase;
}

.sidebar-footer {
    padding: 10px;
    border-top: 1px solid rgba(255,255,255,0.08);
}
.logout-btn:hover { background: rgba(239,68,68,0.2) !important; color: #fca5a5 !important; }

/* ---- Top Bar ---- */
.top-bar {
    background: var(--bg-card);
    padding: 16px 24px;
    display: flex;
    align-items: center;
    gap: 16px;
    border-bottom: 1px solid var(--border);
    position: sticky; top: 0; z-index: 100;
}
.page-title { font-family: var(--font-heading); font-size: 1.15rem; font-weight: 700; }
.top-bar-right { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.free-badge {
    background: var(--warning-light);
    color: #b45309;
    padding: 4px 10px;
    border-radius: 6px;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.5px;
}
.hamburger {
    display: none; background: none; border: none; cursor: pointer;
    width: 28px; height: 20px; position: relative;
}
.hamburger span {
    display: block; width: 100%; height: 2px; background: var(--text);
    position: absolute; left: 0; transition: var(--transition);
}
.hamburger span:nth-child(1) { top: 0; }
.hamburger span:nth-child(2) { top: 9px; }
.hamburger span:nth-child(3) { top: 18px; }

/* ---- Auth Layout (Login/Register) ---- */
.auth-layout {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #0d1b4a;
    padding: 20px;
    position: relative;
}
.auth-layout::before {
    content: '';
    position: absolute; inset: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.03'%3E%3Ccircle cx='30' cy='30' r='2'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}
.auth-card {
    background: var(--bg-card);
    border-radius: 20px;
    padding: 40px;
    width: 100%;
    max-width: 440px;
    box-shadow: var(--shadow-lg);
    position: relative;
    z-index: 1;
}
.auth-logo {
    display: flex; align-items: center; justify-content: center; gap: 10px;
    margin-bottom: 8px;
}
.auth-logo .logo-icon {
    width: 44px; height: 44px;
    background: var(--primary);
}
.auth-logo .logo-text { color: var(--text); font-size: 1.2rem; }
.auth-subtitle { text-align: center; color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 30px; }
.auth-card h2 { text-align: center; font-family: var(--font-heading); margin-bottom: 4px; font-size: 1.25rem; }
.auth-footer { text-align: center; margin-top: 20px; color: var(--text-secondary); font-size: 0.88rem; }
.auth-footer a { font-weight: 600; }

/* ---- Alerts ---- */
.alert {
    padding: 14px 18px;
    border-radius: var(--radius-sm);
    margin-bottom: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    display: flex; align-items: center; gap: 10px;
}
.alert-success { background: var(--success-light); color: #065f46; border-left: 4px solid var(--success); }
.alert-error { background: var(--danger-light); color: #991b1b; border-left: 4px solid var(--danger); }
.alert-warning { background: var(--warning-light); color: #92400e; border-left: 4px solid var(--warning); }
.alert-info { background: var(--primary-light); color: var(--primary-dark); border-left: 4px solid var(--primary); }

/* ---- Form Elements ---- */
.form-group { margin-bottom: 18px; }
.form-group label {
    display: block; font-weight: 600; font-size: 0.85rem;
    margin-bottom: 6px; color: var(--text);
}
.form-control {
    width: 100%; padding: 11px 14px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 0.92rem;
    transition: border-color var(--transition), box-shadow var(--transition);
    background: #fff;
    color: var(--text);
}
.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(26,115,167,0.1);
}
.form-control::placeholder { color: var(--text-muted); }
select.form-control { cursor: pointer; }
textarea.form-control { resize: vertical; min-height: 100px; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-hint { font-size: 0.78rem; color: var(--text-muted); margin-top: 4px; }

/* ---- Buttons ---- */
.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 8px;
    padding: 11px 22px;
    border-radius: var(--radius-sm);
    font-weight: 600; font-size: 0.9rem;
    cursor: pointer; border: 2px solid transparent;
    transition: all var(--transition);
    white-space: nowrap;
}
.btn svg { width: 18px; height: 18px; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-secondary { background: var(--secondary); color: #fff; }
.btn-secondary:hover { background: #239469; }
.btn-outline {
    background: transparent; color: var(--primary);
    border-color: var(--border);
}
.btn-outline:hover { border-color: var(--primary); background: var(--primary-light); }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { background: #dc2626; }
.btn-sm { padding: 7px 14px; font-size: 0.82rem; }
.btn-lg { padding: 14px 28px; font-size: 1rem; }
.btn-block { width: 100%; }
.btn-group { display: flex; gap: 10px; flex-wrap: wrap; }

/* ---- Cards ---- */
.card {
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    padding: 24px;
    transition: box-shadow var(--transition);
}
.card:hover { box-shadow: var(--shadow-md); }
.card-header {
    display: flex; align-items: center; justify-content: space-between;
    margin-bottom: 20px; padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
}
.card-header h3 { font-family: var(--font-heading); font-size: 1.1rem; }
.card-grid { display: grid; gap: 20px; }
.card-grid-2 { grid-template-columns: repeat(auto-fill, minmax(340px, 1fr)); }
.card-grid-3 { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }
.card-grid-4 { grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); }

/* ---- Stat Cards ---- */
.stat-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    padding: 22px;
    display: flex; align-items: flex-start; gap: 16px;
}
.stat-icon {
    width: 48px; height: 48px;
    border-radius: 12px;
    display: flex; align-items: center; justify-content: center;
    flex-shrink: 0;
}
.stat-icon svg { width: 24px; height: 24px; }
.stat-icon.blue { background: var(--primary-light); color: var(--primary); }
.stat-icon.green { background: var(--secondary-light); color: var(--secondary); }
.stat-icon.amber { background: var(--accent-light); color: #b45309; }
.stat-icon.red { background: var(--danger-light); color: var(--danger); }
.stat-info h4 { font-size: 0.8rem; color: var(--text-secondary); font-weight: 500; text-transform: uppercase; letter-spacing: 0.5px; }
.stat-info .stat-value { font-family: var(--font-heading); font-size: 1.5rem; font-weight: 800; line-height: 1.2; }

/* ---- Tables ---- */
.table-wrapper { overflow-x: auto; border-radius: var(--radius); border: 1px solid var(--border); }
.data-table { width: 100%; border-collapse: collapse; }
.data-table th {
    background: var(--bg);
    padding: 12px 16px;
    text-align: left;
    font-size: 0.78rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border);
}
.data-table td {
    padding: 12px 16px;
    border-bottom: 1px solid var(--border);
    font-size: 0.88rem;
}
.data-table tr:last-child td { border-bottom: none; }
.data-table tr:hover td { background: rgba(26,115,167,0.02); }

/* ---- Status Badges ---- */
.status {
    display: inline-flex; align-items: center; gap: 6px;
    padding: 4px 10px; border-radius: 6px;
    font-size: 0.76rem; font-weight: 600;
}
.status::before {
    content: ''; width: 6px; height: 6px; border-radius: 50%;
}
.status-active { background: var(--success-light); color: #065f46; }
.status-active::before { background: var(--success); }
.status-live { background: var(--danger-light); color: #991b1b; }
.status-live::before { background: var(--danger); animation: pulse 1.5s infinite; }
.status-ended, .status-expired { background: var(--bg); color: var(--text-muted); }
.status-ended::before, .status-expired::before { background: var(--text-muted); }
.status-scheduled { background: var(--primary-light); color: var(--primary-dark); }
.status-scheduled::before { background: var(--primary); }
.status-pending { background: #fef3c7; color: #92400e; }
.status-pending::before { background: #f59e0b; }
.status-cancelled { background: #fee2e2; color: #991b1b; }
.status-cancelled::before { background: #ef4444; }

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.3; }
}

/* ---- Class Card ---- */
.class-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
    transition: all var(--transition);
}
.class-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.class-card-banner {
    height: 8px;
    background: var(--primary);
}
.class-card-body { padding: 20px; }
.class-card-body h3 { font-family: var(--font-heading); font-size: 1.05rem; margin-bottom: 6px; }
.class-card-body p { color: var(--text-secondary); font-size: 0.85rem; margin-bottom: 14px; }
.class-card-meta {
    display: flex; align-items: center; gap: 16px;
    color: var(--text-muted); font-size: 0.8rem;
    margin-bottom: 16px;
}
.class-card-meta span { display: flex; align-items: center; gap: 4px; }
.class-card-meta svg { width: 14px; height: 14px; }
.class-code {
    display: inline-block;
    background: var(--primary-light);
    color: var(--primary);
    padding: 4px 10px;
    border-radius: 6px;
    font-family: monospace;
    font-weight: 600;
    font-size: 0.85rem;
    letter-spacing: 1px;
}
.class-card-actions { display: flex; gap: 8px; margin-top: 14px; }

/* ---- Empty State ---- */
.empty-state {
    text-align: center; padding: 60px 20px;
    color: var(--text-secondary);
}
.empty-state svg { width: 64px; height: 64px; margin: 0 auto 16px; opacity: 0.3; }
.empty-state h3 { font-family: var(--font-heading); color: var(--text); margin-bottom: 8px; }
.empty-state p { margin-bottom: 20px; font-size: 0.9rem; }

/* ---- Modal ---- */
.modal-overlay {
    position: fixed; inset: 0;
    background: rgba(0,0,0,0.5);
    display: flex; align-items: center; justify-content: center;
    z-index: 2000; padding: 20px;
    opacity: 0; visibility: hidden;
    transition: all 0.25s;
}
.modal-overlay.active { opacity: 1; visibility: visible; }
.modal {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 32px;
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    transform: translateY(20px);
    transition: transform 0.25s;
}
.modal-overlay.active .modal { transform: translateY(0); }
.modal h3 { font-family: var(--font-heading); margin-bottom: 20px; }

/* ============================================================
   LIVE CLASSROOM
   ============================================================ */
.classroom-layout {
    display: grid;
    grid-template-columns: 1fr 340px;
    grid-template-rows: 1fr auto;
    height: calc(100vh - 64px);
    gap: 0;
}
.classroom-main {
    display: flex;
    flex-direction: column;
    background: #0a0e17;
    overflow: hidden;
}
.classroom-sidebar {
    background: var(--bg-card);
    border-left: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* Video Grid */
.video-grid {
    flex: 1;
    display: grid;
    gap: 8px;
    padding: 12px;
    align-content: center;
}
.video-grid.grid-1 { grid-template-columns: 1fr; }
.video-grid.grid-2 { grid-template-columns: 1fr 1fr; }
.video-grid.grid-3-plus { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }

.video-tile {
    position: relative;
    background: #1a1f2e;
    border-radius: var(--radius);
    overflow: hidden;
    aspect-ratio: 16/9;
    display: flex;
    align-items: center;
    justify-content: center;
}
.video-tile video {
    width: 100%; height: 100%;
    object-fit: cover;
}
.video-tile .avatar-placeholder {
    width: 72px; height: 72px;
    border-radius: 50%;
    background: var(--primary);
    display: flex; align-items: center; justify-content: center;
    font-size: 1.8rem; font-weight: 700; color: #fff;
}
.video-tile-name {
    position: absolute; bottom: 8px; left: 8px;
    background: rgba(0,0,0,0.6);
    color: #fff;
    padding: 4px 10px;
    border-radius: 6px;
    font-size: 0.78rem;
    font-weight: 500;
}
.video-tile-status {
    position: absolute; top: 8px; right: 8px;
    display: flex; gap: 4px;
}
.video-tile-status span {
    width: 28px; height: 28px;
    border-radius: 50%;
    background: rgba(0,0,0,0.5);
    display: flex; align-items: center; justify-content: center;
}
.video-tile-status svg { width: 14px; height: 14px; color: #fff; }
.video-tile-status .muted svg { color: var(--danger); }

/* Classroom Controls */
.classroom-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 16px;
    background: #0a0e17;
}
.control-btn {
    width: 48px; height: 48px;
    border-radius: 50%;
    border: none;
    background: #2a2f3e;
    color: #fff;
    display: flex; align-items: center; justify-content: center;
    cursor: pointer;
    transition: all var(--transition);
}
.control-btn svg { width: 22px; height: 22px; }
.control-btn:hover { background: #3a3f4e; }
.control-btn.active { background: var(--primary); }
.control-btn.danger { background: var(--danger); }
.control-btn.danger:hover { background: #dc2626; }
.control-btn.off { background: var(--danger); }

/* Session Timer */
.session-timer {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #fff;
    font-family: monospace;
    font-size: 1.1rem;
    font-weight: 600;
    padding: 8px 16px;
    background: rgba(255,255,255,0.1);
    border-radius: 8px;
}
.session-timer.warning { color: var(--warning); background: rgba(245,158,11,0.15); }
.session-timer.danger { color: var(--danger); background: rgba(239,68,68,0.15); animation: pulse 1s infinite; }

/* Sidebar Tabs */
.sidebar-tabs {
    display: flex;
    border-bottom: 2px solid var(--border);
}
.sidebar-tab {
    flex: 1;
    padding: 12px;
    text-align: center;
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text-secondary);
    background: none;
    border: none;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    margin-bottom: -2px;
    transition: all var(--transition);
}
.sidebar-tab:hover { color: var(--primary); }
.sidebar-tab.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}
.tab-content { display: none; flex: 1; flex-direction: column; overflow: hidden; }
.tab-content.active { display: flex; }

/* Chat */
.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 12px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.chat-msg {
    max-width: 85%;
}
.chat-msg.own { align-self: flex-end; }
.chat-msg-name { font-size: 0.72rem; font-weight: 600; color: var(--primary); margin-bottom: 2px; }
.chat-msg.own .chat-msg-name { color: var(--secondary); text-align: right; }
.chat-msg-bubble {
    background: var(--bg);
    padding: 8px 12px;
    border-radius: 12px 12px 12px 4px;
    font-size: 0.85rem;
    line-height: 1.4;
}
.chat-msg.own .chat-msg-bubble {
    background: var(--primary-light);
    border-radius: 12px 12px 4px 12px;
}
.chat-msg-time { font-size: 0.65rem; color: var(--text-muted); margin-top: 2px; }
.chat-input-area {
    display: flex; gap: 8px;
    padding: 12px;
    border-top: 1px solid var(--border);
}
.chat-input-area input {
    flex: 1;
    padding: 10px 14px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
}
.chat-input-area input:focus { outline: none; border-color: var(--primary); }
.chat-input-area button {
    padding: 10px 16px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-weight: 600;
}

/* Participants */
.participant-list { padding: 12px; overflow-y: auto; flex: 1; }
.participant-item {
    display: flex; align-items: center; gap: 10px;
    padding: 8px 0;
    border-bottom: 1px solid var(--border);
}
.participant-item:last-child { border: none; }
.participant-avatar {
    width: 34px; height: 34px;
    border-radius: 50%;
    background: var(--primary-light);
    color: var(--primary);
    display: flex; align-items: center; justify-content: center;
    font-weight: 700; font-size: 0.8rem;
}
.participant-name { font-size: 0.85rem; font-weight: 500; }
.participant-role { font-size: 0.7rem; color: var(--text-muted); }

/* Files Panel */
.files-panel { padding: 12px; overflow-y: auto; flex: 1; }
.file-item {
    display: flex; align-items: center; gap: 10px;
    padding: 10px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    margin-bottom: 8px;
    transition: all var(--transition);
}
.file-item:hover { background: var(--bg); }
.file-icon {
    width: 36px; height: 36px;
    border-radius: 8px;
    display: flex; align-items: center; justify-content: center;
    font-size: 0.7rem; font-weight: 700; color: #fff;
}
.file-icon.pdf { background: var(--danger); }
.file-icon.doc { background: var(--primary); }
.file-icon.img { background: var(--secondary); }
.file-icon.other { background: var(--text-muted); }
.file-info { flex: 1; min-width: 0; }
.file-info .name { font-size: 0.82rem; font-weight: 500; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.file-info .meta { font-size: 0.7rem; color: var(--text-muted); }

/* Subscription Page */
.pricing-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 24px; max-width: 800px; margin: 0 auto; }
.pricing-card {
    background: var(--bg-card);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    text-align: center;
    transition: all var(--transition);
}
.pricing-card.featured { border-color: var(--primary); position: relative; }
.pricing-card.featured::before {
    content: 'BEST VALUE';
    position: absolute; top: -12px; left: 50%; transform: translateX(-50%);
    background: var(--primary); color: #fff;
    padding: 4px 16px; border-radius: 20px;
    font-size: 0.7rem; font-weight: 700; letter-spacing: 1px;
}
.pricing-card h3 { font-family: var(--font-heading); font-size: 1.2rem; margin-bottom: 8px; }
.pricing-amount { font-family: var(--font-heading); font-size: 2.2rem; font-weight: 800; color: var(--primary); }
.pricing-period { color: var(--text-muted); font-size: 0.85rem; margin-bottom: 20px; }
.pricing-features { list-style: none; text-align: left; margin-bottom: 24px; }
.pricing-features li {
    padding: 8px 0;
    font-size: 0.88rem;
    color: var(--text-secondary);
    display: flex; align-items: center; gap: 8px;
}
.pricing-features li::before { content: '✓'; color: var(--success); font-weight: 700; }

/* Session Expired Modal */
.expired-overlay {
    position: fixed; inset: 0;
    background: rgba(0,0,0,0.8);
    display: flex; align-items: center; justify-content: center;
    z-index: 5000;
}
.expired-modal {
    background: var(--bg-card);
    border-radius: 20px;
    padding: 48px;
    text-align: center;
    max-width: 460px;
    width: 90%;
}
.expired-modal .icon {
    width: 72px; height: 72px;
    border-radius: 50%;
    background: var(--warning-light);
    margin: 0 auto 20px;
    display: flex; align-items: center; justify-content: center;
}
.expired-modal .icon svg { width: 36px; height: 36px; color: var(--warning); }
.expired-modal h2 { font-family: var(--font-heading); margin-bottom: 12px; }
.expired-modal p { color: var(--text-secondary); margin-bottom: 24px; font-size: 0.92rem; }
.expired-modal .btn-group { justify-content: center; }

/* ---- Responsive ---- */
@media (max-width: 1024px) {
    .classroom-layout { grid-template-columns: 1fr; }
    .classroom-sidebar { display: none; position: fixed; right: 0; top: 0; bottom: 0; width: 340px; z-index: 1000; }
    .classroom-sidebar.open { display: flex; }
}

@media (max-width: 768px) {
    .sidebar { transform: translateX(-100%); }
    .sidebar.open { transform: translateX(0); }
    .sidebar-close { display: block; }
    .hamburger { display: block; }
    .main-content { margin-left: 0; }
    .content-area { padding: 16px; }
    .form-row { grid-template-columns: 1fr; }
    .card-grid-2, .card-grid-3, .card-grid-4 { grid-template-columns: 1fr; }
    .stat-card { padding: 16px; }
    .stat-info .stat-value { font-size: 1.4rem; }
    .pricing-cards { grid-template-columns: 1fr; }
    .auth-card { padding: 28px; }
    .video-grid.grid-2 { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
    .top-bar { padding: 12px 16px; }
    .page-title { font-size: 1.05rem; }
    .auth-card { padding: 24px 20px; }
}

/* ---- Utility ---- */
.text-center { text-align: center; }
.text-right { text-align: right; }
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.gap-sm { gap: 8px; }
.d-flex { display: flex; }
.align-center { align-items: center; }
.justify-between { justify-content: space-between; }
.flex-wrap { flex-wrap: wrap; }
.w-100 { width: 100%; }
.hidden { display: none !important; }