.product-detail-wrapper { max-width: 1200px; margin: 30px auto; padding: 0 15px; }
    
    /* Bố cục tổng thể dạng 2 cột: Cột chính (trái) và Cột Sidebar (phải) */
    .ecommerce-layout { display: grid; grid-template-columns: 1fr 320px; gap: 25px; align-items: start; }
    
    .product-main-grid { display: grid; grid-template-columns: 1fr 1.2fr; gap: 30px; background: #fff; padding: 25px; border-radius: 12px; border: 1px solid #e2e8f0; box-shadow: 0 4px 20px rgba(0,0,0,0.03); }
    
    /* Gallery ảnh phụ */
    .gallery-thumbs { display: flex; gap: 10px; margin-top: 12px; overflow-x: auto; padding-bottom: 5px; }
    .gallery-thumb-item { width: 65px; height: 65px; border-radius: 6px; overflow: hidden; border: 2px solid #cbd5e1; cursor: pointer; flex-shrink: 0; transition: 0.2s; }
    .gallery-thumb-item:hover, .gallery-thumb-item.active { border-color: #eb1838; }
    .gallery-thumb-item img { width: 100%; height: 100%; object-fit: cover; }

    .product-info-box h1 { font-size: 22px; font-weight: 800; color: #0f172a; margin: 6px 0 10px 0; line-height: 1.4; }
    .product-price-box { font-size: 24px; font-weight: 800; color: #eb1838; margin-bottom: 12px; }
    .product-attr-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; background: #f8fafc; padding: 12px; border-radius: 8px; border: 1px solid #e2e8f0; margin-bottom: 15px; font-size: 13px; color: #334155; }
    
    /* Cụm tăng giảm số lượng chuyên nghiệp */
    .quantity-selector {
        display: flex;
        align-items: center;
        background: #f8fafc;
        border: 1px solid #cbd5e1;
        border-radius: 8px;
        overflow: hidden;
        height: 46px;
        flex-shrink: 0;
    }
    .quantity-btn {
        background: transparent;
        border: none;
        width: 34px;
        height: 100%;
        font-size: 13px;
        font-weight: 700;
        color: #475569;
        cursor: pointer;
        transition: 0.2s;
        display: flex;
        align-items: center;
        justify-content: center;
    }
    .quantity-btn:hover { background: #e2e8f0; color: #0f172a; }
    .quantity-input {
        width: 40px;
        height: 100%;
        border: none;
        background: transparent;
        text-align: center;
        font-size: 14px;
        font-weight: 700;
        color: #0f172a;
        outline: none;
    }
    .quantity-input::-webkit-outer-spin-button,
    .quantity-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }

    /* Sidebar Styles */
    .ecommerce-sidebar { display: flex; flex-direction: column; gap: 20px; }
    .sidebar-card { background: #fff; border: 1px solid #e2e8f0; border-radius: 12px; padding: 20px; box-shadow: 0 4px 15px rgba(0,0,0,0.02); }
    .sidebar-title { font-size: 15px; font-weight: 800; color: #0f172a; margin-bottom: 15px; padding-bottom: 8px; border-bottom: 2px solid #f1f5f9; display: flex; align-items: center; gap: 8px; }

    /* Lưới sản phẩm liên quan & sản phẩm mới */
    .products-grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 15px; }
    .product-card-item { background: #fff; border: 1px solid #e2e8f0; border-radius: 10px; overflow: hidden; display: flex; flex-direction: column; transition: 0.2s; text-decoration: none; }
    .product-card-item:hover { transform: translateY(-3px); box-shadow: 0 6px 20px rgba(0,0,0,0.06); border-color: #cbd5e1; }

    @media screen and (max-width: 1024px) {
        .ecommerce-layout { grid-template-columns: 1fr; }
        .product-main-grid { grid-template-columns: 1fr; gap: 20px; }
        .products-grid-4 { grid-template-columns: repeat(2, 1fr); }
    }
    @media screen and (max-width: 768px) {
        .product-detail-wrapper { margin: 15px auto; }
        .product-main-grid { padding: 15px; }
        .product-price-box { font-size: 20px; }
        .product-attr-grid { grid-template-columns: 1fr; }
        .product-action-buttons { flex-direction: column; width: 100%; }
        .product-action-buttons button { width: 100% !important; }
        #productForm { flex-direction: column; align-items: stretch !important; }
        .quantity-selector { width: 100%; justify-content: center; }
        .products-grid-4 { grid-template-columns: 1fr; }
    }