So honestly after using the site for a few days, a couple things stick out that could make this better.
>1. A couple additional themes.
>2. CSS tweaks to make things more symmetrical and easier to read.
>3. Native extension like 4chan has.
For the native extension, a floating quick-reply, auto-update by default, centering threads, enforcing HTTPS, etc.
For the CSS tweaks, having the font at 75% or 80% is kind of small, you would be better off setting it to 100% and changing default pixel values.
For additional themes, Photon would be good and possibly something like Lainchan's CyberPunk.