:root {
    /* Colors */
    --bg-primary: #000000;
    --bg-secondary: #0a0a0a;
    --bg-gradient: linear-gradient(to bottom right, #000000, #0a0a0a, #141414);
    --surface-color: rgba(255, 255, 255, 0.05);
    --surface-color-hover: rgba(255, 255, 255, 0.08);
    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.7);
    --primary-color: #0099ff;
    --primary-gradient: linear-gradient(135deg, #0099ff, #0066ff);
    --error-color: #ff4444;
    --success-color: #00cc88;
    --border-color: rgba(255, 255, 255, 0.1);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;

    /* Border Radius */
    --border-radius-sm: 0.25rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 1rem;
    --border-radius-xl: 1.5rem;

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.3);
    --glow: 0 0 20px rgba(0, 153, 255, 0.3);
}

/* Global Styles */
body {
    margin: 0;
    padding: 0;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-gradient);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.5;
}

/* App Container */
.app-container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--surface-color);
    backdrop-filter: blur(10px);
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
    position: fixed;
    height: 100vh;
    transition: transform 0.3s ease;
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: 280px;
    padding: var(--spacing-xl);
    min-height: 100vh;
}

/* Logo */
.logo {
    font-size: 1.5rem;
    font-weight: 700;
    margin: 0 0 var(--spacing-xl);
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: glow 3s ease-in-out infinite alternate;
}

/* Navigation */
.nav-item {
    display: flex;
    align-items: center;
    padding: var(--spacing-md);
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: var(--border-radius-md);
    margin-bottom: var(--spacing-sm);
    transition: all 0.2s ease;
}

.nav-item:hover {
    background: var(--surface-color-hover);
    color: var(--text-primary);
    transform: translateX(4px);
}

.nav-item.active {
    background: var(--primary-gradient);
    color: var(--text-primary);
}

.nav-icon {
    margin-right: var(--spacing-md);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius-md);
    font-weight: 500;
    transition: all 0.2s ease;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: var(--primary-gradient);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--glow);
}

.btn-secondary {
    background: var(--surface-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--surface-color-hover);
}

.btn-danger {
    background: var(--error-color);
    color: white;
}

.w-100 {
    width: 100%;
}

/* Loading Animation */
@keyframes spin {
    to { transform: rotate(360deg); }
}

.loading {
    display: inline-block;
    width: 24px;
    height: 24px;
    border: 2px solid var(--text-secondary);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

/* Glow Animation */
@keyframes glow {
    from {
        text-shadow: 0 0 10px rgba(0, 153, 255, 0.5),
                     0 0 20px rgba(0, 153, 255, 0.3),
                     0 0 30px rgba(0, 153, 255, 0.2);
    }
    to {
        text-shadow: 0 0 20px rgba(0, 153, 255, 0.6),
                     0 0 30px rgba(0, 153, 255, 0.4),
                     0 0 40px rgba(0, 153, 255, 0.2);
    }
}

/* Fade In Animation */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.fade-in {
    animation: fadeIn 0.3s ease-out;
}

/* Mobile Navigation */
.mobile-nav-toggle {
    display: none;
    position: fixed;
    top: var(--spacing-md);
    right: var(--spacing-md);
    z-index: 1000;
    background: var(--surface-color);
    border: none;
    padding: var(--spacing-sm);
    border-radius: var(--border-radius-md);
    cursor: pointer;
}

/* Responsive Design */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
        z-index: 999;
    }

    .sidebar.active {
        transform: translateX(0);
    }

    .main-content {
        margin-left: 0;
        padding: var(--spacing-lg);
    }

    .mobile-nav-toggle {
        display: block;
    }

    .content-grid {
        grid-template-columns: 1fr;
    }
}

/* Logout Button */
.btn-logout {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    color: var(--text-secondary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s ease;
    width: 100%;
}

.btn-logout:hover {
    background: var(--surface-color-hover);
    color: var(--text-primary);
    border-color: var(--primary-color);
}

.btn-logout svg {
    transition: transform 0.2s ease;
}

.btn-logout:hover svg {
    transform: translateX(4px);
}

/* User Info */
.user-info {
    margin-top: auto;
    padding: var(--spacing-md);
    border-top: 1px solid var(--border-color);
}

.username {
    display: block;
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

/* Loading States */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(5px);
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--text-secondary);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

/* Forms */
.form-group {
    margin-bottom: var(--spacing-md);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
}

.form-input {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    font-size: 1rem;
    transition: border-color 0.2s ease;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Cards */
.card {
    background-color: var(--surface-color);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-lg);
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.3s ease forwards;
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }
.mt-5 { margin-top: var(--spacing-xl); }

.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }