Hi there,
I'm just previewing on mobile, but the css grid stuff looks fine to me. If you want to improve it, I'd look into area and line names next, as all the numbers (especially written in shorthand) are difficult to read. If you used grid line or area names, other developers would be able to see where everything is placed on your grid at an easy glance.
I also think your layouts would be easier if you went mobile first with css / media queries.
Only other point for improvement is on alt text. As an assistive technology user, it wouldn't tell me anything to hear 'user 1 read out as an image description. Better to use the person's name or leave alt intentionally blank.
That's all from me. Well done on. This and keep going! 👏 ☺