I really like material-ui but am constantly bummed about their use of inline styles.

Each component has multiple style props, lest you resort to "div > div > div:nth-child(2)" in your own CSS.

Each "style" prop now has to be diffed by React too.

Doing things like hover on mouse/touch events seems like it will never be as efficient as using ":hover".

And when doing universal rendering, the amount of markup you send is huge. And you have to disable the browser-prefixing of style props.

Having said all that, the material-ui library is still great.

We just wrote all our own inline styles to override their stuff. It turned out to be not that bad. We just set up a context object like theirs, and wrapped all the components we used.