These images may be overlapping.

In this demo, the height of each item in the grid depends on the image. If Shuffle is initialized before the images load, the heights it calculates will be incorrect.

Go to this images demo for a solutions.

Shuffle will call layout() again once the window's load event fires to resolve this and other async assets (like fonts) which could affect the size of your items. Resizing the window would also fix it.

A deep blue lake sits in the middle of vast hills covered with evergreen trees
Lake Walchen
Looking down over one of the pillars of the Golden Gate Bridge to the roadside and water below
Golden Gate Bridge
A close, profile view of a crocodile looking directly into the camera
Crocodile
SpaceX launches a Falcon 9 rocket from Cape Canaveral Air Force Station
SpaceX
A multi-level highway stack interchange in Puxi, Shanghai
Crossroads
Dimly lit mountains give way to a starry night showing the Milky Way
Milky Way
NASA Satellite view of Earth
Earth
A close up of a turtle underwater
Turtle
Many trees stand alonside a hill which overlooks a pedestrian path, next to the ocean at Stanley Park in Vancouver, Canada
Stanley Park
An intrigued cat sits in grass next to a flag planted in front of it with an astronaut space kitty sticker on beige fabric.
Astronaut Cat
Pier 14 at night, looking towards downtown San Francisco's brightly lit buildings
San Francisco
Looking down on central park and the surrounding builds from the Rockefellar Center
Central Park