For now the project is badly covered by the tests. It can be greatly improved.

Is your feature request related to a problem? Please describe.
I use theme-ui on daily basis on personal and work projects. The documentation is quite large and I just want to remember something that I used before so I navigate the whole docs to get it.

Adding search in docs page will make it easy to remember things fast instead of navigating the documentation.

**Describe the solution

References

• https://gitter.im/colour-science/colour?at=5f622c705fde567ffa4f66f5