:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-card: #1e293b;
    --bg-card-hover: #273549;
    --border-color: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --primary: #3b82f6;
    --primary-hover: #2563eb;
    --success: #10b981;
    --success-bg: rgba(16, 185, 129, 0.15);
    --warning: #f59e0b;
    --warning-bg: rgba(245, 158, 11, 0.15);
    --danger: #ef4444;
    --danger-bg: rgba(239, 68, 68, 0.15);
    --info: #06b6d4;
    --sidebar-width: 260px;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

[data-theme="light"] {
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --bg-card-hover: #f1f5f9;
    --border-color: #e2e8f0;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
}

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

.sidebar {
    width: var(--sidebar-width);
    background-color: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
}

.brand {
    padding: 1.5rem 1.25rem;
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.brand-badge {
    background: linear-gradient(135deg, #3b82f6, #8b5cf6);
    color: white;
    font-size: 0.7rem;
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-weight: 600;
}

.nav-menu {
    list-style: none;
    padding: 1rem 0.75rem;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    flex: 1;
}

.nav-item a {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.65rem 0.85rem;
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: 6px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.15s ease-in-out;
}

.nav-item a:hover {
    background-color: var(--bg-card-hover);
    color: var(--text-primary);
}

.nav-item.active a {
    background-color: var(--primary);
    color: white;
}

.sidebar-footer {
    padding: 1rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
}

.topbar {
    height: 60px;
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1.5rem;
    position: sticky;
    top: 0;
    z-index: 10;
}

.page-body {
    padding: 1.5rem;
    flex: 1;
}

/* Cards & Stats */
.grid-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.stat-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.25rem;
}

.stat-card .label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.stat-card .value {
    font-size: 1.85rem;
    font-weight: 700;
    margin: 0.35rem 0;
}

.stat-card .subtext {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 1.5rem;
    overflow: hidden;
}

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

.card-title {
    font-size: 1rem;
    font-weight: 600;
}

.card-body {
    padding: 1.25rem;
}

/* Badges */
.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.2rem 0.55rem;
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: 4px;
    text-transform: uppercase;
}

.badge-success { background: var(--success-bg); color: var(--success); }
.badge-warning { background: var(--warning-bg); color: var(--warning); }
.badge-danger { background: var(--danger-bg); color: var(--danger); }
.badge-info { background: rgba(6, 182, 212, 0.15); color: var(--info); }
.badge-muted { background: rgba(100, 116, 139, 0.2); color: var(--text-muted); }

/* Tables */
.table-responsive {
    width: 100%;
    overflow-x: auto;
}

.table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
    text-align: left;
}

.table th {
    padding: 0.75rem 1rem;
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    font-weight: 600;
    border-bottom: 1px solid var(--border-color);
}

.table td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
}

.table tbody tr:hover {
    background-color: var(--bg-card-hover);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 0.9rem;
    font-size: 0.85rem;
    font-weight: 500;
    border-radius: 6px;
    border: 1px solid transparent;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.15s ease;
}

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

.btn-secondary { background-color: transparent; border-color: var(--border-color); color: var(--text-primary); }
.btn-secondary:hover { background-color: var(--bg-card-hover); }

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

.btn-sm {
    padding: 0.3rem 0.6rem;
    font-size: 0.75rem;
}

/* Forms */
.form-group {
    margin-bottom: 1rem;
}

.form-label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 0.35rem;
    color: var(--text-secondary);
}

.form-control {
    width: 100%;
    padding: 0.55rem 0.75rem;
    font-size: 0.875rem;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-family: inherit;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
}

/* Drag & Drop Upload Zone */
.dropzone {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 2.5rem 1.5rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
    background-color: var(--bg-primary);
}

.dropzone:hover, .dropzone.dragover {
    border-color: var(--primary);
    background-color: rgba(59, 130, 246, 0.05);
}

/* Code & Pre */
pre, code {
    font-family: var(--font-mono);
}

pre {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    padding: 1rem;
    border-radius: 6px;
    overflow-x: auto;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        display: none;
    }
    .app-container {
        flex-direction: column;
    }
}