Cannot resize logo images in CSS

I’m working on my product landing page but for some reasons I can’t get the images I’m using for logos to resize and I have no clue what I’m doing wrong. Please help.

You don’t have any CSS.

I had stuff but deleted it in frustration when it literally did nothing.

You can use max-width to make the image’s size responsive.

Not working, don’t know if the issue is how I wrote the HTML or what.

Hi, I have viewed your codepen. Try using the header-img id in your <img> instead of the logo class in your <div> that is:
#header-img {

Thank you so much, you have been of great help.