The problem is with the image height.
if you set
#content .category_grid_view li a.post_img img { height: 97px }
the Grid View will display good, but the image will look distorted.
try to resize the image to make it look good and keep the height to 97px.
EDIT
@Bdalte's comment
try to put each element/product into a div (let's say with the class wrapper) and set the height with the max height you get from your elements/products. based on Find out divs height and setting div height you can use this script
var maxHeight = 0;
$('div.wrapper')
.each(function() { maxHeight = Math.max(maxHeight, $(this).height()); })
.height(maxHeight);
it should look like this