Simple Lightbox

A simple lightbox made from HTML, CSS, and Javascript. No jQuery or plugins.
Video below demonstrates functionality.

1. Click an image to open its lightbox
2. Click left and right arrows to traverse images, X to escape
3. Press left and right arrow keys to traverse images, ESC to escape
4. While scrolling through page, lightbox stays fixed to centre

Visit Simple Lightbox here.
Visit Github Directory to see code.