body{font-family:Arial,sans-serif;background-color:#f8f9fa}header{background-color:#004085;color:#fff;padding:10px 0;text-align:center}footer{background-color:#004085;color:#fff;padding:10px 0;text-align:center}.container{width:80%;margin:0 auto}.sidebar{background-color:#e9ecef;padding:10px}.product-listing{display:flex;flex-wrap:wrap}.product-item{width:30%;margin:10px;padding:10px;border:1px solid #dee2e6;background-color:#fff;text-align:center}