/* ============================================================
   CLASSROOM STAR — Layout CSS
   Sidebar, Header, Content area, Responsive
   ============================================================ */

/* ── App Shell ───────────────────────────────────────────── */
.app-shell {
    display: flex;
    min-height: 100vh;
    background: var(--clr-bg-primary);
}

/* ── Sidebar ─────────────────────────────────────────────── */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--sidebar-width);
    height: 100vh;
    background: var(--grad-sidebar);
    border-right: 1px solid var(--clr-border);
    display: flex;
    flex-direction: column;
    z-index: 100;
    transition: var(--transition-base);
    overflow: hidden;
}

/* Sidebar Brand */
.sidebar-brand {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-5) var(--space-5);
    border-bottom: 1px solid var(--clr-border);
    text-decoration: none;
    min-height: var(--header-height);
    flex-shrink: 0;
}
.sidebar-brand-icon {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-md);
    background: var(--grad-gold);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    flex-shrink: 0;
    box-shadow: var(--shadow-gold);
}
.sidebar-brand-text {
    display: flex;
    flex-direction: column;
    overflow: hidden;
}
.sidebar-brand-name {
    font-size: var(--fs-md);
    font-weight: 800;
    color: var(--clr-text-primary);
    white-space: nowrap;
    letter-spacing: -0.03em;
}
.sidebar-brand-tagline {
    font-size: var(--fs-xs);
    color: var(--clr-text-muted);
    white-space: nowrap;
}

/* Sidebar Navigation */
.sidebar-nav {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    padding: var(--space-4) 0;
}
.sidebar-nav::-webkit-scrollbar { width: 4px; }

.nav-section-label {
    font-size: var(--fs-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--clr-text-muted);
    padding: var(--space-4) var(--space-5) var(--space-2);
}

.nav-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3) var(--space-5);
    color: var(--clr-text-secondary);
    text-decoration: none;
    font-size: var(--fs-sm);
    font-weight: 500;
    border-radius: 0;
    transition: var(--transition-fast);
    position: relative;
    white-space: nowrap;
    border-left: 3px solid transparent;
    margin: 1px 0;
}
.nav-item:hover {
    color: var(--clr-text-primary);
    background: rgba(255, 255, 255, 0.05);
    text-decoration: none;
}
.nav-item.active {
    color: var(--clr-gold-400);
    background: rgba(255, 193, 7, 0.08);
    border-left-color: var(--clr-gold-400);
    font-weight: 600;
}
.nav-item .nav-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
    opacity: 0.7;
}
.nav-item.active .nav-icon { opacity: 1; color: var(--clr-gold-400); }
.nav-item .nav-badge {
    margin-left: auto;
    background: var(--clr-gold-500);
    color: var(--clr-text-inverse);
    font-size: 10px;
    font-weight: 700;
    padding: 1px 6px;
    border-radius: var(--radius-full);
}

/* Sidebar Footer */
.sidebar-footer {
    padding: var(--space-4);
    border-top: 1px solid var(--clr-border);
    flex-shrink: 0;
}
.sidebar-user {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3);
    border-radius: var(--radius-md);
    background: rgba(255,255,255,0.04);
    text-decoration: none;
    transition: var(--transition-fast);
}
.sidebar-user:hover {
    background: rgba(255,255,255,0.08);
    text-decoration: none;
}
.sidebar-user-info {
    flex: 1;
    min-width: 0;
    overflow: hidden;
}
.sidebar-user-name {
    font-size: var(--fs-sm);
    font-weight: 600;
    color: var(--clr-text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.sidebar-user-role {
    font-size: var(--fs-xs);
    color: var(--clr-text-muted);
}

/* ── Main Content ─────────────────────────────────────────── */
.main-content {
    flex: 1;
    margin-left: var(--sidebar-width);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: var(--transition-base);
    min-width: 0;
}

/* ── Top Header ──────────────────────────────────────────── */
.top-header {
    position: sticky;
    top: 0;
    z-index: 50;
    height: var(--header-height);
    background: rgba(13, 15, 26, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--clr-border);
    display: flex;
    align-items: center;
    padding: 0 var(--space-8);
    gap: var(--space-4);
}
.header-menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--clr-text-secondary);
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--radius-sm);
    transition: var(--transition-fast);
}
.header-menu-toggle:hover { color: var(--clr-text-primary); background: rgba(255,255,255,0.07); }

.header-title {
    font-size: var(--fs-lg);
    font-weight: 700;
    color: var(--clr-text-primary);
    flex: 1;
}
.header-subtitle {
    font-size: var(--fs-xs);
    color: var(--clr-text-muted);
    font-weight: 400;
}
.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

/* ── Page Content ─────────────────────────────────────────── */
.page-content {
    flex: 1;
    padding: var(--space-8);
    max-width: var(--content-max-width);
    width: 100%;
    animation: fadeIn 0.35s ease;
}

/* ── Page Header ─────────────────────────────────────────── */
.page-header {
    margin-bottom: var(--space-8);
}
.page-header h1 {
    font-size: var(--fs-2xl);
    margin-bottom: var(--space-1);
}
.page-header p {
    font-size: var(--fs-sm);
    color: var(--clr-text-muted);
}
.page-header-row {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: var(--space-4);
    flex-wrap: wrap;
}

/* ── Overlay for mobile sidebar ──────────────────────────── */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.6);
    z-index: 99;
    backdrop-filter: blur(2px);
}
.sidebar-overlay.active { display: block; }

/* ── Responsive ──────────────────────────────────────────── */
@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
    }
    .sidebar.open {
        transform: translateX(0);
    }
    .main-content {
        margin-left: 0;
    }
    .header-menu-toggle {
        display: flex;
    }
    .page-content {
        padding: var(--space-6);
    }
}

@media (max-width: 768px) {
    .page-content {
        padding: var(--space-4);
    }
    .top-header {
        padding: 0 var(--space-4);
    }
    .page-header-row {
        flex-direction: column;
        align-items: stretch;
    }
}

@media (max-width: 480px) {
    .page-content { padding: var(--space-3); }
}

/* ── Auth Layout (login page) ────────────────────────────── */
.auth-layout {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-6);
    background: var(--clr-bg-primary);
    position: relative;
    overflow: hidden;
}
/* Decorative background blobs */
.auth-layout::before,
.auth-layout::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    pointer-events: none;
    z-index: 0;
}
.auth-layout::before {
    width: 500px; height: 500px;
    background: radial-gradient(circle, rgba(255,193,7,0.12) 0%, transparent 70%);
    top: -150px; right: -100px;
}
.auth-layout::after {
    width: 400px; height: 400px;
    background: radial-gradient(circle, rgba(124,77,255,0.1) 0%, transparent 70%);
    bottom: -100px; left: -100px;
}

.auth-card {
    position: relative;
    z-index: 1;
    width: 100%;
    max-width: 420px;
    background: var(--clr-bg-card);
    border: 1px solid var(--clr-border);
    border-radius: var(--radius-xl);
    padding: var(--space-10) var(--space-8);
    box-shadow: var(--shadow-lg), inset 0 1px 0 rgba(255,255,255,0.07);
    animation: fadeIn 0.5s ease;
}

/* ── Grid utilities ───────────────────────────────────────── */
.grid { display: grid; }
.grid-2 { grid-template-columns: repeat(2, 1fr); gap: var(--space-4); }
.grid-3 { grid-template-columns: repeat(3, 1fr); gap: var(--space-4); }
.grid-4 { grid-template-columns: repeat(4, 1fr); gap: var(--space-4); }

@media (max-width: 1024px) {
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

/* ── Flex utilities ───────────────────────────────────────── */
.flex        { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.flex-between { display: flex; align-items: center; justify-content: space-between; }
.flex-wrap   { flex-wrap: wrap; }
.gap-2       { gap: var(--space-2); }
.gap-3       { gap: var(--space-3); }
.gap-4       { gap: var(--space-4); }
.gap-6       { gap: var(--space-6); }