{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Colors */
    --primary: #667eea;
    --primary-light: #8b9fef;
    --primary-dark: #5568d3;
    --secondary: #764ba2;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --info: #3b82f6;

    /* Light Theme */
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --border: #e5e7eb;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.2);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;

    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;

    /* Sidebar */
    --sidebar-width: 280px;
    --topbar-height: 70px;
}

[data-theme="dark"] {
    --bg-primary: #1f2937;
    --bg-secondary: #111827;
    --bg-tertiary: #374151;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-tertiary: #9ca3af;
    --border: #4b5563;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.6);
}

html, body {
    font-family: var(--font-family);
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    transition: background-color var(--transition-base), color var(--transition-base);
    height: 100%;
    overflow: hidden;
}

#app {
    display: grid;
    grid-template-columns: var(--sidebar-width) 1fr;
    grid-template-rows: var(--topbar-height) 1fr;
    height: 100vh;
    width: 100vw;
    background-color: var(--bg-secondary);
}

/* ============ SIDEBAR ============ */
.sidebar {
    grid-column: 1;
    grid-row: 1 / -1;
    background-color: var(--bg-primary);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    box-shadow: 2px 0 8px rgba(0, 0, 0, 0.1);
    z-index: 100;
    transition: transform var(--transition-base);
}

.logo {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    cursor: pointer;
}

.logo-icon {
    font-size: 2rem;
    animation: bounce 2s infinite;
}

.logo-text h1 {
    font-size: var(--font-size-lg);
    font-weight: 700;
    margin: 0;
    line-height: 1.2;
}

.logo-text p {
    font-size: var(--font-size-xs);
    color: var(--text-secondary);
    margin: 0;
}

.main-nav {
    flex: 1;
    padding: var(--spacing-lg) 0;
    display: flex;
    flex-direction: column;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    color: var(--text-secondary);
    text-decoration: none;
    transition: all var(--transition-base);
    border-left: 3px solid transparent;
    position: relative;
}

.nav-item:hover {
    background-color: var(--bg-tertiary);
    color: var(--primary);
    padding-left: calc(var(--spacing-lg) + 4px);
}

.nav-item.active {
    background-color: var(--bg-tertiary);
    color: var(--primary);
    border-left-color: var(--primary);
    font-weight: 600;
}

.nav-item .icon {
    font-size: 1.25rem;
    min-width: 1.5rem;
}

.nav-item .label {
    flex: 1;
    font-size: var(--font-size-sm);
}

.sidebar-footer {
    padding: var(--spacing-lg);
    border-top: 1px solid var(--border);
    display: flex;
    gap: var(--spacing-md);
}

.theme-toggle,
.sidebar-collapse {
    flex: 1;
    padding: var(--spacing-md);
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    transition: all var(--transition-base);
    color: var(--text-primary);
    font-size: var(--font-size-lg);
}

.theme-toggle:hover,
.sidebar-collapse:hover {
    background-color: var(--primary);
    color: white;
    transform: scale(1.05);
}

/* ============ TOP BAR ============ */
.top-bar {
    grid-column: 2;
    grid-row: 1;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    padding: 0 var(--spacing-xl);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    z-index: 99;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    margin-right: var(--spacing-lg);
}

.mobile-menu-toggle span {
    width: 24px;
    height: 3px;
    background-color: var(--text-primary);
    transition: all var(--transition-base);
}

.top-bar-content {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-xl);
}

.search-box {
    flex: 1;
    max-width: 400px;
}

.search-box input {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 8px;
    font-family: var(--font-family);
    color: var(--text-primary);
    transition: all var(--transition-base);
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    background-color: var(--bg-primary);
}

.top-bar-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: 8px;
    transition: background-color var(--transition-base);
}

.user-profile:hover {
    background-color: var(--bg-tertiary);
}

.avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: white;
}

.user-info {
    display: flex;
    flex-direction: column;
}

.user-name {
    font-weight: 600;
    font-size: var(--font-size-sm);
    color: var(--text-primary);
}

.user-role {
    font-size: var(--font-size-xs);
    color: var(--text-secondary);
}

.btn-icon {
    position: relative;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: var(--bg-tertiary);
    border: none;
    font-size: 1.25rem;
    cursor: pointer;
    transition: all var(--transition-base);
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-icon:hover {
    background-color: var(--primary);
    transform: scale(1.1);
}

.notification-badge {
    position: absolute;
    top: -5px;
    right: -5px;
    background-color: var(--danger);
    color: white;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xs);
    font-weight: 700;
}

/* ============ MAIN CONTENT ============ */
.main-content {
    grid-column: 2;
    grid-row: 2;
    overflow-y: auto;
    background-color: var(--bg-secondary);
    padding: var(--spacing-xl);
}

.page-container {
    max-width: 1400px;
    margin: 0 auto;
    animation: fadeIn var(--transition-base);
}

/* ============ BUTTONS ============ */
.btn {
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: 8px;
    font-family: var(--font-family);
    font-size: var(--font-size-sm);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    white-space: nowrap;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

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

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

.btn-success:hover {
    filter: brightness(0.9);
}

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

.btn-danger:hover {
    filter: brightness(0.9);
}

.btn-sm {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-xs);
}

/* ============ FORMS ============ */
.form-group {
    margin-bottom: var(--spacing-lg);
}

label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
    font-size: var(--font-size-sm);
    color: var(--text-primary);
}

input,
textarea,
select {
    width: 100%;
    padding: var(--spacing-md);
    background-color: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: 8px;
    font-family: var(--font-family);
    color: var(--text-primary);
    font-size: var(--font-size-sm);
    transition: all var(--transition-base);
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

textarea {
    resize: vertical;
    min-height: 120px;
}

/* ============ CARDS ============ */
.card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
}

.card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--primary);
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border);
}

.card-header h3 {
    margin: 0;
    font-size: var(--font-size-lg);
    color: var(--text-primary);
}

.card-body {
    margin-bottom: var(--spacing-lg);
}

.card-footer {
    display: flex;
    gap: var(--spacing-md);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border);
}

/* ============ GRID ============ */
.grid {
    display: grid;
    gap: var(--spacing-lg);
}

.grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.grid-4 {
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

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

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-5px); }
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

@keyframes slideInLeft {
    from {
        transform: translateX(-100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* ============ LOADING SPINNER ============ */
.loading-spinner {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 9999;
}

.loading-spinner.active {
    display: flex;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.loading-spinner p {
    color: white;
    margin-top: var(--spacing-lg);
    font-weight: 600;
}

/* ============ MODAL ============ */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn var(--transition-base);
}

.modal.active {
    display: flex;
}

.modal-content {
    background-color: var(--bg-primary);
    border-radius: 12px;
    padding: var(--spacing-2xl);
    max-width: 500px;
    width: 90%;
    position: relative;
    animation: fadeIn var(--transition-base);
}

.modal-close {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    width: 40px;
    height: 40px;
    border: none;
    background: none;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-secondary);
    transition: color var(--transition-base);
}

.modal-close:hover {
    color: var(--text-primary);
}

/* ============ TOAST ============ */
.toast-container {
    position: fixed;
    top: var(--spacing-xl);
    right: var(--spacing-xl);
    z-index: 2000;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.toast {
    background-color: var(--bg-primary);
    border-left: 4px solid var(--primary);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: 8px;
    box-shadow: var(--shadow-lg);
    animation: slideInLeft var(--transition-base);
    max-width: 400px;
}

.toast.success {
    border-left-color: var(--success);
}

.toast.warning {
    border-left-color: var(--warning);
}

.toast.danger {
    border-left-color: var(--danger);
}

/* ============ UTILITIES ============ */
.flex {
    display: flex;
}

.flex-between {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.flex-center {
    display: flex;
    align-items: center;
    justify-content: center;
}

.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }

.text-center { text-align: center; }
.text-right { text-align: right; }

.text-sm { font-size: var(--font-size-sm); }
.text-base { font-size: var(--font-size-base); }
.text-lg { font-size: var(--font-size-lg); }

.font-bold { font-weight: 700; }
.font-600 { font-weight: 600; }

.opacity-50 { opacity: 0.5; }
.opacity-75 { opacity: 0.75; }

.hidden { display: none !important; }
.visible { display: block !important; }