Since we first mentioned CSS-in-JS as an emerging technique in 2017, it has become much more popular, a trend we also see in our work. With some solid production experience under our belts, we can now recommend CSS-in-JS as a technique to trial. A good starting point is the styled components framework, which we mentioned in our previous Radar. Next to all the positives, though, there usually is a downside when using CSS-in-JS: the calculation of styles at runtime can cause a noticeable lag for end users. With Linaria we're now seeing a new class of frameworks that were created with this issue in mind. Linaria employs a number of techniques to shift most of the performance overhead to build time. Alas, this does come with its own set of trade-offs, most notably a lack of dynamic style support in IE11.