Everything should be 100% responsive
Your website should work regardless of a users device or screensize. Don't break the functionality of HTML with CSS.
Principles
Everything should be readable on any device
Just because it's readable to you on your laptop, doesn't mean it is readable by your users on their device. Make sure your type is big. Make sure your contrast is high.
Everything should be as performant as possible
Code isn't for making a developers life easier. It's for improving the lives of our users. If it's not doing that, why write it. A developer's time is not precious. A user's time is.
Designing in the browser should be easy
If a computer can do it, you shouldn't have to.
Doing one thing extremely well promotes reusability
Single purpose classes that are easy to grock.
Modules > Monoliths
Tachyons isn't a monolithic framework. It's a collection of 48 self contained modules that can be mixed and matched or used independently. Pick what you want, leave the rest.
Features
Built on Rework
A flexible plugin framework for preprocessing css. View on Github
Mobile-first css architecture
Base classes are mobile by default. Can be overridden by namespaced classes targeting larger breakpoints.
Default colors for rapid theming
Who cares about colors. Unless you're painting a bikeshed.
CSS layout debugging utilities.
Small css modules for debugging stacking and layout issues. Can easily be turned on or off during development.
Composable classes
Construct anything from complex layouts to responsive components with a series of single purpose classes.
Ratio-based scale design systems
Powers of two. Starting at .25
Easy to customize and extend
Take what you need. Leave the rest. Small and flat css modules make it easy to grab only what you need without needing to figure out dependencies.
Responsive Grid
Infinitely nestable. Fully fluid. Extremely light-weight.
Gulp based build system
Minification, auto-prefixing, and so much more.
Testimonials
"It seems silly at first to write code that looks like inline HTML styling but Tachyons works. Instead of wasting time hunting down and dealing with CSS overrides, I now spend time iterating on the design... which is what we're supposed to be doing in the first place :)"
"CSS frameworks shouldn't be one-size-fits-all. Tachyons nails it with its modular approach, eliminating bloat from day one."
Tachyons on NPM
Tachyons is just a series of css modules. They are available on npm and github so that you can mix and match to suit your project's needs. Since tachyons module architecture optimizes for gzip compression most of them are extremely small (well under a kilobyte) so you can start using them without adding bloat to your css.
npm install --save-dev tachyons-module-name