i think it may be an issue specific to the browser you're using. when i look at your page on my phone with chrome, i see the two columns stacked on top of each other with blank space to the right, but no blank space before the images. when i use firefox, the columns are side by side with no blank space below, which is what you want.
browsers have some default css, so there's probably some difference in margins or padding thats causing your problem. you can overwrite the browser defaults by specifying a value in your own css!