The layout fails on Google Chrome. It shows the "Simple Assignment Tracking" etc. chapters each on separate vertical space, and "Partner Up" goes below "Sign up" and "Take the Tour"-buttons.

Yes, I blame Chrome and not your site.

Update: I find the images on http://soshiku.com/tour a bit too big -- the page is really big right now (i.e. lots of pixels). Lots to scroll even on a 1920x1200 resolution.

An me nagging about such small detail proves that you overall design works for me!