:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --success: #16a34a;
    --bg-light: #f3f4f6;
    --text-main: #1f2937;
    --text-muted: #6b7280;
    --border-color: #e5e7eb;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-light);
    color: var(--text-main);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    width: 100%;
    max-width: 900px;
    padding: 20px;
}

.layout-wrapper {
    display: flex;
    gap: 24px;
    align-items: flex-start;
}

.left-panel {
    flex: 1.8;
}

.right-panel {
    flex: 1;
    min-width: 280px;
    position: sticky;
    top: 20px;
}

.card {
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 40px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

.header {
    text-align: center;
    margin-bottom: 30px;
}

.header h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 8px;
    color: #111827;
}

.header p {
    color: var(--text-muted);
    font-size: 1rem;
}

/* Upload Area */
.upload-area {
    border: 2px dashed #cbd5e1;
    border-radius: 12px;
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
    background: #fafafa;
}

.upload-area:hover, .upload-area.dragover {
    border-color: var(--primary);
    background: #eff6ff;
}

.upload-icon {
    color: var(--text-muted);
    margin-bottom: 16px;
    transition: color 0.2s ease;
}

.upload-area:hover .upload-icon, .upload-area.dragover .upload-icon {
    color: var(--primary);
}

.upload-area h3 {
    font-size: 1.125rem;
    margin-bottom: 8px;
    font-weight: 600;
    color: #334155;
}

.upload-area p {
    color: var(--text-muted);
    margin-bottom: 16px;
}

.browse-btn {
    color: var(--primary);
    font-weight: 500;
    cursor: pointer;
}

.browse-btn:hover {
    text-decoration: underline;
}

.supported-files {
    font-size: 0.85rem;
    color: #94a3b8;
}

.success-notification {
    background: #dcfce7;
    color: #166534;
    padding: 8px 16px;
    border-radius: 6px;
    display: inline-block;
    margin-top: 12px;
    font-size: 0.9rem;
    font-weight: 500;
    opacity: 1;
    transition: opacity 0.3s ease;
}

.success-notification.hidden {
    opacity: 0;
    pointer-events: none;
}

/* Sidebar Styles */
.sidebar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: #111827;
}

.file-count {
    background: #e2e8f0;
    color: #475569;
    padding: 2px 8px;
    border-radius: 9999px;
    font-size: 0.85rem;
    font-weight: 600;
}

.empty-state {
    color: var(--text-muted);
    font-size: 0.95rem;
    text-align: center;
    padding: 20px 0;
    font-style: italic;
}

.empty-state.hidden {
    display: none;
}

.sidebar-file-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.sidebar-file-item {
    background: #f8fafc;
    border: 1px solid var(--border-color);
    padding: 12px;
    border-radius: 8px;
    font-size: 0.9rem;
    color: var(--text-main);
    word-break: break-all;
    display: flex;
    align-items: flex-start;
    gap: 8px;
}

.sidebar-file-item::before {
    content: "📄";
    font-size: 1.1rem;
}

/* Responsive */
@media (max-width: 768px) {
    .layout-wrapper {
        flex-direction: column;
    }
    .right-panel {
        width: 100%;
    }
}

@media (max-width: 480px) {
    .card {
        padding: 30px 20px;
    }
    .header h1 {
        font-size: 1.25rem;
    }
    .upload-area {
        padding: 30px 15px;
    }
}