:root {
    --bg-main: #090e17; /* Deep midnight blue */
    --sidebar-bg: rgba(15, 23, 42, 0.6);
    --card-bg: rgba(30, 41, 59, 0.4);
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --accent: #8b5cf6; /* Vibrant Purple */
    --accent-hover: #7c3aed;
    --accent-gradient: linear-gradient(135deg, #8b5cf6, #3b82f6);
    --success: #10b981;
    --danger: #ef4444;
    --glass-border: rgba(255, 255, 255, 0.08);
    --shadow: 0 10px 40px -10px rgba(0,0,0,0.5);
    --sidebar-width: 260px;
    
    --stat-bg: rgba(255, 255, 255, 0.03);
    --input-bg: rgba(0,0,0,0.2);
}

body.light-theme {
    --bg-main: #f8fafc;
    --sidebar-bg: rgba(255, 255, 255, 0.9);
    --card-bg: rgba(255, 255, 255, 0.8);
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --glass-border: rgba(0, 0, 0, 0.1);
    --shadow: 0 10px 40px -10px rgba(0,0,0,0.1);
    
    --stat-bg: rgba(0, 0, 0, 0.02);
    --input-bg: #ffffff;
    color-scheme: light;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    overflow-x: hidden;
    position: relative;
    transition: background-color 0.3s, color 0.3s;
    color-scheme: dark;
}

/* Background atmospheric glows */
body::before {
    content: '';
    position: fixed;
    top: -20%; left: -10%;
    width: 50vw; height: 50vw;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.15) 0%, transparent 60%);
    z-index: -1;
}
body::after {
    content: '';
    position: fixed;
    bottom: -20%; right: -10%;
    width: 60vw; height: 60vw;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.1) 0%, transparent 60%);
    z-index: -1;
}

/* Layout */
.app-container {
    display: flex;
    width: 100%;
}

/* Sidebar Navigation */
.sidebar {
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    backdrop-filter: blur(20px);
    border-right: 1px solid var(--glass-border);
    display: flex;
    flex-direction: column;
    position: fixed;
    height: 100vh;
    left: 0;
    top: 0;
    z-index: 100;
}

.brand {
    padding: 2rem;
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    border-bottom: 1px solid var(--glass-border);
}

.nav-links {
    padding: 1.5rem 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    flex: 1;
    overflow-y: auto;
}

.nav-item {
    padding: 0.85rem 1.2rem;
    border-radius: 12px;
    color: var(--text-secondary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 1rem;
    font-weight: 500;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.nav-item i { font-size: 1.1rem; width: 20px; text-align: center; }

.nav-item:hover {
    color: var(--text-primary);
    background: rgba(125, 125, 125, 0.1);
}

.nav-item.active {
    background: var(--accent-gradient);
    color: white;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.3);
}
body.light-theme .nav-item.active { color: white; }

/* Main Content Area */
.main-wrapper {
    flex: 1;
    margin-left: var(--sidebar-width);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Top Header */
.top-header {
    height: 80px;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: transparent;
}

.search-bar {
    position: relative;
    width: 300px;
}
.search-bar input {
    width: 100%;
    background: var(--card-bg);
    border: 1px solid var(--glass-border);
    padding: 0.6rem 2.5rem;
    border-radius: 20px;
    color: var(--text-primary);
    backdrop-filter: blur(10px);
}
.search-bar i {
    position: absolute;
    left: 1rem; top: 50%; transform: translateY(-50%);
    color: var(--text-secondary);
    z-index: 2;
    pointer-events: none;
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}
.avatar {
    width: 40px; height: 40px;
    border-radius: 50%;
    background: var(--accent-gradient);
    display: flex; justify-content: center; align-items: center;
    font-weight: bold;
    color: white;
}

main {
    padding: 1rem 2.5rem 3rem;
    flex: 1;
}

/* Page Headers */
.page-header {
    margin-bottom: 2rem;
}
.page-header h2 {
    font-size: 1.8rem;
    font-weight: 600;
    letter-spacing: -0.5px;
}

/* Buttons */
.btn {
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    border: none;
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s ease;
    font-size: 0.9rem;
}
.btn-primary {
    background: var(--accent-gradient);
    color: white;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.3);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(139, 92, 246, 0.4); }
.btn-default {
    background: var(--card-bg);
    color: var(--text-primary);
    border: 1px solid var(--glass-border);
}
.btn-default:hover { background: rgba(125,125,125,0.1); }

/* Glass Cards (Tables & Forms) */
.glass-card {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

/* Dashboard Specifics */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
    margin-bottom: 2rem;
}
.stat-card {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    box-shadow: var(--shadow);
}
.stat-icon {
    width: 50px; height: 50px;
    border-radius: 12px;
    display: flex; justify-content: center; align-items: center;
    font-size: 1.5rem;
    color: white;
}
.stat-info h4 {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    font-weight: 500;
}
.stat-info .value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}
.charts-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 1.5rem;
}
.chart-container {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
}
.chart-container h3 {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
    color: var(--text-primary);
}

/* Tables */
table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0 0.5rem;
}
th {
    padding: 1rem;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    text-align: left;
    border-bottom: 1px solid var(--glass-border);
}
td {
    padding: 1rem;
    background: var(--stat-bg);
    font-size: 0.9rem;
}
tr td:first-child { border-top-left-radius: 8px; border-bottom-left-radius: 8px; }
tr td:last-child { border-top-right-radius: 8px; border-bottom-right-radius: 8px; }
tr:hover td { background: rgba(125, 125, 125, 0.1); }

/* Forms */
.form-group { margin-bottom: 1.5rem; }
.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
}
.form-group input, .form-group select {
    width: 100%;
    background: var(--input-bg);
    border: 1px solid var(--glass-border);
    padding: 0.8rem 1rem;
    border-radius: 8px;
    color: var(--text-primary);
    transition: all 0.3s ease;
}
.form-group select option {
    background: var(--bg-main);
    color: var(--text-primary);
}
.form-group input:focus, .form-group select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 2px rgba(139, 92, 246, 0.2);
}

/* Action Buttons */
.action-btn {
    width: 32px; height: 32px;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    display: inline-flex; justify-content: center; align-items: center;
    color: white;
    transition: transform 0.2s;
}
.action-btn:hover { transform: scale(1.1); }
.action-btn.edit { background: rgba(59, 130, 246, 0.2); color: #3b82f6; }
.action-btn.delete { background: rgba(239, 68, 68, 0.2); color: #ef4444; }

/* Submenu */
.submenu { display: none; padding-left: 2.5rem; padding-top: 0.5rem; }
.submenu.active { display: flex; flex-direction: column; gap: 0.5rem; }
.submenu a { color: var(--text-secondary); text-decoration: none; font-size: 0.85rem; padding: 0.4rem 0; cursor: pointer; }
.submenu a:hover { color: var(--text-primary); }

/* Popups (Notifications, User Profile, Search) */
.popup-menu {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: 10px;
    background: var(--card-bg);
    backdrop-filter: blur(25px);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    min-width: 250px;
    box-shadow: var(--shadow);
    z-index: 1000;
    flex-direction: column;
}
.popup-menu.active {
    display: flex;
    animation: fadeIn 0.2s ease;
}
.popup-header {
    padding: 1rem;
    font-weight: 600;
    border-bottom: 1px solid var(--glass-border);
    color: var(--text-primary);
    font-size: 0.95rem;
}
.popup-item {
    padding: 0.8rem 1rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}
.popup-item:hover {
    background: rgba(125, 125, 125, 0.1);
    color: var(--text-primary);
}

/* Footer */
footer {
    text-align: center;
    padding: 1.5rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
    border-top: 1px solid var(--glass-border);
}

.flex-between { display: flex; justify-content: space-between; align-items: center; }
.toolbar { margin-bottom: 1.5rem; display:flex; gap:1rem; }