BUG: [please help] 5 columns structure layout bug

I tried to add 5 columns to display part of the contents of my webpage, as I have 5 reading plan groups that I want to show to our members. The first four columns are display normally, but the fifth column texts are shrunk into width of 40, while other columns are divided equally with a width of 200.

I checked and tried to change the padding / margin values for the fifth column, but it made no change. Please help.

The page I need help with: [log in to see the link]