K7: Lightweight Vanilla JS Gallery Lightbox

K7 is a lightweight vanilla JavaScript gallery lightbox at ~7.7 KB, bundling JS and CSS in a single file with no dependencies. It supports fullscreen overlay, keyboard and swipe navigation, autoplay, image download, high-res loading, and CSS custom properties for theming. It activates with a single script tag, making it ideal for portfolios, product galleries, and documentation sites.