center column is pushing right column down

On a 3 column format, the center column is pushing the right column down and below the center column.

This seems to be especially true, if using shorter Post Settings like 600 to 800 chars and there is an image or table.

Setting the Post setting to "unlimited" clears this issue.

I have seen this before with other themes, but I can't recall how to fix the issue.

Please advise and thanks