CSS display: inline-block drops to next line

Question

I have a simple grid that I am testing out.

I decided to change something from float: left to display: inline-block in the attribute select

Answer 1

@Thielicious's answer has a fine solution. Here's the explanation, and the answer to your

I am wondering why when using float: left there is enough space for col-9 and everything works fine but, when using display: inline-block the element drops down to the next line.

Whitespace between inline-block elements takes up space on the rendered page.

Chris Coyier gives a run down of different ways to get around this (includes the method of html comments, as in Thielicious's answer, as well as some other HTML tricks and CSS methods)