:root {
    --primary: #6366f1;
    --primary-hover: #4f46e5;
    --secondary: #64748b;
    --bg-main: #f8fafc;
    --bg-sidebar: #ffffff;
    --bg-card: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.5;
}

.app-container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background-color: var(--bg-sidebar);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    position: sticky;
    top: 0;
    height: 100vh;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 2rem;
}

nav {
    flex: 1;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    text-decoration: none;
    color: var(--text-muted);
    border-radius: 0.5rem;
    transition: all 0.2s;
    margin-bottom: 0.5rem;
}

.nav-item:hover, .nav-item.active {
    background-color: #f1f5f9;
    color: var(--primary);
}

.nav-item.active {
    font-weight: 600;
    background-color: #eef2ff;
}

.sidebar-footer {
    padding-top: 1rem;
    border-top: 1px solid var(--border);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.avatar {
    width: 40px;
    height: 40px;
    background-color: var(--primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
}

.user-info p {
    font-size: 0.875rem;
}

.user-info .name {
    font-weight: 600;
}

.user-info .role {
    color: var(--text-muted);
    font-size: 0.75rem;
}

/* Main Content */
.main-content {
    flex: 1;
    padding: 2rem;
    max-width: 1400px;
    margin: 0 auto;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.search-container {
    display: flex;
    background: white;
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    padding: 0.25rem;
    width: 400px;
}

.search-container input {
    border: none;
    padding: 0.5rem 1rem;
    flex: 1;
    outline: none;
}

.search-container button {
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
}

.btn {
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
}

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

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

/* Dashboard Stats */
.view {
    display: none;
}

.view.active {
    display: block;
}

.view-title {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--bg-card);
    padding: 1.5rem;
    border-radius: 1rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    box-shadow: var(--shadow);
    transition: transform 0.2s;
}

.stat-card:hover {
    transform: translateY(-4px);
}

.stat-icon {
    width: 48px;
    height: 48px;
    border-radius: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.stat-icon.books { background: #e0e7ff; color: var(--primary); }
.stat-icon.available { background: #dcfce7; color: var(--success); }
.stat-icon.active-borrow { background: #fef9c3; color: var(--warning); }
.stat-icon.overdue { background: #fee2e2; color: var(--danger); }

.stat-details h3 {
    font-size: 1.5rem;
    font-weight: 700;
}

.stat-details p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Cards & Tables */
.card {
    background: white;
    border-radius: 1rem;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.card-header {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.card-header h2 {
    font-size: 1.25rem;
}

.view-all {
    color: var(--primary);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
}

.card-body {
    padding: 0;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
}

.data-table th, .data-table td {
    padding: 1rem 1.5rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.data-table th {
    background: #f8fafc;
    font-size: 0.75rem;
    text-transform: uppercase;
    font-weight: 600;
    color: var(--text-muted);
}

.data-table tr:last-child td {
    border-bottom: none;
}

.badge {
    padding: 0.25rem 0.5rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 600;
}

.badge-success { background: #dcfce7; color: #166534; }
.badge-warning { background: #fef9c3; color: #854d0e; }
.badge-danger { background: #fee2e2; color: #991b1b; }

@media (max-width: 768px) {
    .sidebar { width: 80px; padding: 1rem 0.5rem; }
    .sidebar .text, .sidebar .user-info { display: none; }
    .search-container { width: 200px; }
}