/* Premium Design System */
:root {
    --bg-color: #f8fafc;
    --sidebar-bg: #0f172a;
    --sidebar-text: #94a3b8;
    --sidebar-hover: #1e293b;
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --card-bg: #ffffff;
    --accent: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius: 12px;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-main);
    display: flex;
    height: 100vh;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background-color: var(--sidebar-bg);
    color: white;
    display: flex;
    flex-direction: column;
    transition: all 0.3s ease;
    box-shadow: 2px 0 10px rgba(0,0,0,0.1);
}

.sidebar-header {
    padding: 24px;
    font-size: 20px;
    font-weight: 700;
    letter-spacing: 0.5px;
    display: flex;
    align-items: center;
    gap: 12px;
    border-bottom: 1px solid rgba(255,255,255,0.05);
}

.nav-menu {
    flex: 1;
    padding: 20px 0;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.nav-item {
    padding: 12px 24px;
    color: var(--sidebar-text);
    text-decoration: none;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 12px;
    transition: all 0.2s ease;
    cursor: pointer;
}

.nav-item:hover, .nav-item.active {
    background-color: var(--sidebar-hover);
    color: white;
    border-right: 4px solid var(--primary-color);
}

/* Main Content */
.main-content {
    flex: 1;
    overflow-y: auto;
    padding: 32px 48px;
    position: relative;
}

.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 32px;
}

.page-title {
    font-size: 28px;
    font-weight: 700;
    color: var(--text-main);
}

.section {
    display: none;
    animation: fadeIn 0.4s ease forwards;
}

.section.active {
    display: block;
}

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

/* Cards & Layout */
.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 24px;
}

/* Tables */
.table-container {
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    overflow: hidden;
}

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

th {
    background-color: #f1f5f9;
    padding: 16px;
    text-align: left;
    font-size: 13px;
    text-transform: uppercase;
    color: var(--text-muted);
    font-weight: 600;
    border-bottom: 1px solid var(--border-color);
}

td {
    padding: 16px;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-main);
    font-size: 14px;
}

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

tr:hover td {
    background-color: #f8fafc;
}

/* Forms & Inputs */
.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-main);
}

input, select {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 15px;
    font-family: inherit;
    transition: all 0.2s ease;
    background-color: #f8fafc;
}

input:focus, select:focus {
    outline: none;
    border-color: var(--primary-color);
    background-color: white;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: 8px;
    font-weight: 600;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
    text-decoration: none;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.btn-outline {
    background-color: transparent;
    color: var(--primary-color);
    border: 1px solid var(--primary-color);
}

.btn-outline:hover {
    background-color: #eff6ff;
}

.btn-small {
    padding: 6px 12px;
    font-size: 12px;
}

/* Badge / Tags */
.badge {
    padding: 4px 10px;
    border-radius: 99px;
    font-size: 12px;
    font-weight: 600;
}
.badge.success { background: #dcfce7; color: #166534; }
.badge.warning { background: #fef9c3; color: #854d0e; }
.badge.danger { background: #fee2e2; color: #991b1b; }

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(15, 23, 42, 0.5);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
    z-index: 1000;
}

.modal-overlay.active {
    opacity: 1;
    pointer-events: auto;
}

.modal {
    background: white;
    border-radius: var(--radius);
    width: 100%;
    max-width: 500px;
    padding: 32px;
    transform: translateY(20px);
    transition: transform 0.3s ease;
    box-shadow: var(--shadow-lg);
}

.modal-overlay.active .modal {
    transform: translateY(0);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.modal-title {
    font-size: 20px;
    font-weight: 700;
}

.modal-close {
    cursor: pointer;
    color: var(--text-muted);
    font-size: 24px;
    background: none;
    border: none;
}

/* Utility */
.mb-4 { margin-bottom: 16px; }
.mb-6 { margin-bottom: 24px; }
.mt-4 { margin-top: 16px; }
.mt-6 { margin-top: 24px; }
.flex { display: flex; }
.gap-4 { gap: 16px; }
.gap-2 { gap: 8px; }
.w-full { width: 100%; }
.text-center { text-align: center; }
.empty-state {
    padding: 48px;
    text-align: center;
    color: var(--text-muted);
}