Okay, let's create the structure and basic styling for your high-end engineering website with a marketplace section.

This sets up the basic HTML structure, CSS styling with an engineering aesthetic (dark theme, specific fonts, clean layout), and JavaScript to handle the marketplace icon clicks and display placeholder product data. The design is responsive and should adapt to different screen sizes.

Okay, I'll add an engineering-themed background specifically to the marketplace section and ensure the products are displayed as a clear, visually appealing list when an icon is clicked.

I've updated the style.css to add a subtle background pattern to the #marketplace section and refined the styles for the icons and the product display area. The product display now uses a ul (unordered list) with the class product-list for better semantic structure and styling, presenting the items clearly. I also added simple Font Awesome icons to the HTML for visual representation within the category circles and updated the JavaScript slightly to use the new list structure.