gutter determines the space between columns. If the border setting is used, it must be less than or equal to the gutter. gutter is an integer value and defaults to 5 You can also go for a tight look by setting both gutter and margin to 0.
itemwidth The width for a grid item automatically defaults to the width of the image. You can set the width for the grid item. The caption and the excerpt will stretch to fit the grid item while the image will default to it’s native width and height unless specified otherwise. To stretch the image, set