:root {
    /* Primary Palette - Premium Vibrant Colors */
    --primary: #10b981;
    --primary-rgb: 16, 185, 129;
    --secondary: #059669;
    --accent: #34d399;
    
    /* Neutral Palette - Ultra Clean */
    --bg-main: #f8fafc;
    --bg-card: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    
    /* Glassmorphism - Premium */
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-border: rgba(255, 255, 255, 0.2);
    --glass-blur: 20px;
    
    --sidebar-bg: #ffffff;
    --sidebar-text: #64748b;
    --sidebar-text-active: #ffffff;
    --sidebar-border: rgba(0,0,0,0.05);
    --sidebar-item-hover: #f1f5f9;
    
    /* Gradients - Smooth & Modern */
    --grad-primary: linear-gradient(135deg, var(--primary), var(--secondary));
    --grad-accent: linear-gradient(135deg, var(--accent), var(--primary));
    --grad-dark: linear-gradient(135deg, #0f172a, #1e293b);
    
    /* Shadows - Layered & Soft */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.07), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-premium: 0 15px 30px -10px rgba(var(--primary-rgb), 0.3);
    
    --radius-sm: 10px;
    --radius-md: 16px;
    --radius-lg: 24px;
    --radius-xl: 32px;
    --radius-full: 9999px;
    
    --sidebar-width: 280px;
    --header-height: 70px;
    --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme='dark'] {
    --bg-main: #020617;
    --bg-card: #0f172a;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #1e293b;
    --glass-bg: rgba(15, 23, 42, 0.85);
    --glass-border: rgba(255, 255, 255, 0.05);
    --sidebar-bg: #0f172a;
    --sidebar-text: #94a3b8;
    --sidebar-border: rgba(255,255,255,0.05);
    --sidebar-item-hover: rgba(255,255,255,0.05);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    transition: background-color 0.4s ease;
    overflow-x: hidden;
    min-height: 100vh;
}

/* Premium Scrollbar */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 10px; }
::-webkit-scrollbar-thumb:hover { background: var(--primary); }

/* Layout Structure */
.app-layout {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    border-right: 1px solid var(--sidebar-border);
    display: flex;
    flex-direction: column;
    height: 100vh;
    position: sticky;
    top: 0;
    transition: var(--transition);
    z-index: 1000;
}

.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
    background: var(--bg-main);
    position: relative;
}

.top-header {
    height: var(--header-height);
    background: var(--glass-bg);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    position: sticky;
    top: 0;
    z-index: 900;
}

/* Premium Components */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 20px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 0;
    background: var(--grad-primary);
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.card:hover::before {
    height: 100%;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    text-decoration: none;
    font-size: 0.95rem;
    letter-spacing: 0.3px;
}

.btn-primary {
    background: var(--grad-primary);
    color: white;
    box-shadow: var(--shadow-premium);
}

.btn-primary:hover {
    filter: brightness(1.1);
    transform: scale(1.02);
}

.btn-icon {
    width: 42px;
    height: 42px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-main);
    color: var(--text-main);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.btn-icon:hover {
    background: var(--grad-primary);
    color: white;
    border-color: transparent;
}

/* Native-Like Mobile Navigation */
.mobile-nav {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: calc(70px + env(safe-area-inset-bottom));
    background: var(--glass-bg);
    backdrop-filter: blur(25px);
    -webkit-backdrop-filter: blur(25px);
    border-top: 1px solid var(--border-color);
    z-index: 2000;
    justify-content: space-around;
    align-items: center;
    padding: 0 10px calc(env(safe-area-inset-bottom) + 5px);
    box-shadow: 0 -10px 40px rgba(0,0,0,0.08);
}

.mobile-nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 5px;
    text-decoration: none;
    color: var(--text-muted);
    font-size: 0.7rem;
    font-weight: 700;
    transition: var(--transition);
    padding: 10px;
    border-radius: 20px;
    min-width: 65px;
    position: relative;
}

.mobile-nav-item i {
    font-size: 1.5rem;
    transition: transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.mobile-nav-item.active {
    color: var(--primary);
}

.mobile-nav-item.active i {
    transform: translateY(-8px) scale(1.2);
    color: var(--primary);
}

.mobile-nav-item.active::after {
    content: '';
    position: absolute;
    bottom: 8px;
    width: 6px;
    height: 6px;
    background: var(--primary);
    border-radius: 50%;
    box-shadow: 0 0 10px var(--primary);
}

/* Full Responsive Overrides */
@media (max-width: 1024px) {
    .sidebar { width: 80px; }
    .sidebar-header h3, .nav-links span, .nav-label { display: none; }
}

@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -100%;
        width: 85% !important;
        max-width: 320px;
        height: 100vh;
        box-shadow: 30px 0 60px rgba(0,0,0,0.2);
    }

    .sidebar.active {
        left: 0;
    }

    .sidebar-header h3, .nav-links span { display: block !important; }

    .top-header {
        padding: 0 16px;
        height: 65px;
    }

    .mobile-nav { display: flex; }

    .content-wrapper {
        padding: 16px !important;
        padding-bottom: 100px !important;
    }

    .grid-2, .grid-3, .grid-4 {
        grid-template-columns: 1fr !important;
        gap: 16px;
    }
}

/* Dynamic Grid System */
.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1200px) {
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

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

@media (max-width: 768px) {
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr !important; }
    .dashboard-container { padding: 10px !important; }
}

.dashboard-grid { grid-template-columns: 2fr 1fr; }

@media (max-width: 1024px) {
    .dashboard-grid { grid-template-columns: 1fr; }
}
    /* Premium Mobile Lists */
    .mobile-list-item {
        background: var(--bg-card);
        border-radius: var(--radius-md);
        padding: 16px;
        margin-bottom: 12px;
        border: 1px solid var(--border-color);
        display: flex;
        align-items: center;
        gap: 15px;
        box-shadow: var(--shadow-sm);
    }

    .mobile-list-icon {
        width: 50px;
        height: 50px;
        border-radius: 14px;
        background: var(--grad-primary);
        color: white;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 1.4rem;
        flex-shrink: 0;
    }
}

/* Online Class & Task Specific Styles */
.class-status-badge {
    padding: 4px 10px;
    border-radius: 8px;
    font-size: 0.7rem;
    font-weight: 800;
    text-transform: uppercase;
}

.status-live { background: #fee2e2; color: #ef4444; animation: pulse 2s infinite; }
.status-upcoming { background: #dcfce7; color: #10b981; }

@keyframes pulse {
    0% { opacity: 1; }
    50% { opacity: 0.5; }
    100% { opacity: 1; }
}

.progress-container {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin: 10px 0;
}

.progress-bar {
    height: 100%;
    background: var(--grad-primary);
    transition: width 1s ease-in-out;
}

/* Animations */
.animate-in {
    animation: slideUp 0.5s ease forwards;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Utility */
.glass {
    background: var(--glass-bg);
    backdrop-filter: blur(var(--glass-blur));
    border: 1px solid var(--glass-border);
}