I have no really info why HN guys decided to go thirty but... I bet it's because gives the screen a great height. I believe that with 30 you have to scroll dow

I have no really info why HN guys decided to go thirty but... I bet it's because gives the screen a great height. I believe that with 30 you have to scroll down only once on most monitors, and still 30 is a great number of content in single page.