Blueprint CSS
A CSS framework that aims to cut down on your CSS development time
...Because it’s designed as a structural foundation rather than a themed UI kit, it’s easy to layer branding and custom design on top without fighting the base styles. The framework includes mixins, modifier classes, and responsive breakpoints so layouts adapt fluidly across screen sizes. By starting with a consistent baseline, Blueprint CSS reduces cross-browser quirks and gives designers confidence in spacing, proportion, and element alignment. Teams often use it as the “CSS backbone” of internal tools, web products, or component libraries.