That topic is outdated, so I’m going to archive it…
If you’d like to change the hover color for these filter buttons above the topic list:
You can do this, since we use some variables:
:root {
--d-nav-bg-color--hover: #fab1ed;
}
There are a whole set of variables for this nav that can be edited in the same way:
For general reference: Make CSS changes on Your Site