The only suggestions I'd have for you is using semantic HTML. For example, you used a div and gave it the class "main-container", but you could just use the <main> tags and that also helps the browser understand where the main information is.
The only other thing I noticed is that you didn't use heading hierarchy, so you used h4 and h5 without using any of the higher hierarchy headings. It's good practice to have an h1 always and then follow the chain of headings. This was weird for me at the beginning, but it's more about the HTML structure than the styling.
Other than that, I think you did really good on this project!
Try to use an organized heading structure, you used an h4 here for the title, but it would be better to use an h1 and style it as you need.
Look up text size guides, in this case the text could be a bit small (I know, I know, one pixel is a bit too naggy). I think a good starting point is that paragraph texts are usually 16px or 1rem, from there you can also give your headings bigger size depending on their hierarchy.
I checked up your code, you seem to have left the styling for the links under the box on the HTML file, maybe that's why it's pulling the styles from there instead of the CSS.
Other than that I think you did pretty good!
Maybe my one suggestion would be to try and use semantic HTML, replacing divs with main, container, figure, etc.
Hopefully this can help you fix the links color. You're doing great, keep it up!