You are alone in having this problem.
Probably, your browser did not fetch the appropriate stylesheet or javascript.
Try these in order:
Check your 8ch.net options (upper right corner) and make sure the theme selected is board-specific.
If that doesn't help, try forced refresh (CTRL F5).
If that doesn't fix it, close your browser and restart the browser.
If that doesn't fix it, use your browser's tools and delete site's offline data for 8ch.net then restart browser.
Good luck.
That's all I will say.