Getting 404 on sites assets

One of my sub-site is located here:
https://site-name.test/kb/

But it's getting 404 on all assets. Here's an example URL.
https://site-name.test/kb/wp-content/themes/twentytwelve/style.css

My main WP site is located in the root `https://site-name.test/`, while the rest are located in sub-directories.

Any ideas?
