@sacummings91 This looks good, but I have a few comments.

(1)

There may be a few more packages we can safely upgrade (i.e., w/o breaking changes). I put an arrow next to the ones I think can be upgraded safely based on the fact that we updated the same package a few months back or the CHANGELOG seems backward compatible.

$ npm outdated
Package                 Current  Wanted   Latest  Location
copy-webpack-plugin       5.1.1   5.1.1    6.0.3  mineral-ui <==
css-loader                3.4.2   3.4.2    4.1.1  mineral-ui <==
flow-bin                 0.89.0  0.89.0  0.130.0  mineral-ui
flow-typed                2.5.1   2.5.1    3.2.1  mineral-ui
focus-trap-react          3.1.2   3.1.2    7.0.1  mineral-ui
fs-extra                  8.1.0   8.1.0    9.0.1  mineral-ui <==
happo-plugin-puppeteer    1.1.1   1.1.1    1.3.2  mineral-ui
happo.io                  3.6.2   3.6.2    5.6.1  mineral-ui
html-webpack-plugin       3.2.0   3.2.0    4.3.0  mineral-ui <==
husky                     1.2.0   1.2.0    4.2.5  mineral-ui
jest                     24.5.0  24.5.0   26.2.1  mineral-ui <==
memoize-one               4.0.3   4.0.3    5.1.1  mineral-ui <==
polished                  2.3.0   2.3.0    3.6.5  mineral-ui
prettier                 1.19.1  1.19.1    2.0.5  mineral-ui
react                    16.6.3  16.6.3  16.13.1  mineral-ui
react-dom                16.6.3  16.6.3  16.13.1  mineral-ui
react-helmet              5.2.1   5.2.1    6.1.0  mineral-ui <==
react-live               1.12.0  1.12.0    2.2.2  mineral-ui
react-popper              1.3.3   1.3.3    2.2.3  mineral-ui
react-router-dom          4.3.1   4.3.1    5.2.0  mineral-ui
react-transition-group    2.3.0   2.3.0    4.4.1  mineral-ui

(2)

When I do a clean install (rm -r node_modules; npm install or npm list), I see the following peer dependency errors:

npm ERR! peer dep missing: react@^16.13.1, required by [email protected]
npm ERR! peer dep missing: acorn@^6.0.0, required by [email protected]

react-test-renderer is a dependency of enzyme-adapter-react-16. Since we've chosen not to upgrade React at this time, we may need to explicitly pin the version of react-test-renderer that works with React 16.6.x.

acorn-dynamic-import is a dependency of buble, which is a dependency of react-live, which I believe is used on the Mineral-UI website (not library). To resolve this issue, I think we just need to install acorn explicitly.

Can you look into these two and update the PR, if it makes sense to do so?