Responsive Uniform Image Boxes CSS

I am providing CSS and HTML....

I have a gallery where the first pic in each row currently needs to be the size of the other two images of each row. I need the CSS rewritten so each image is the same size, and scales fluidly with the viewport, yet still preserves the photo’s original aspect ratio.

The job is purely front-end: update the style sheet and, if necessary, adjust the container markup so the solution works across modern browsers and common breakpoints without relying on JavaScript. A quick code comment explaining any key declarations will be enough documentation for me.

Deliverables
• Updated CSS (or SCSS) file ready to drop in
• One demo HTML snippet showing the gallery in action
• Brief note on the technique you used (e.g. flexbox, grid, object-fit) so I can maintain it later

I’ll test by resizing the browser and confirming every image box remains the same responsive size while each photo keeps its natural proportions and stays centered.

For Reference here is the website - https://trivantage.com/resource-center

* click on the PRODUCT INFO DOCUMENTS TAB

Also please see image for how it looks now.