- Update the "Getting the Code" section to specifically mention Mozilla Firefox, since while the development viewer *works* it may look slightly "broken" in Chromium-based browsers. (This is caused by a lack of support for unprefixed CSS properties, e.g. `mask-image`, however this does *not* affect the built PDF.js viewer.)

 - Remove the Twitter-link, since that account has not been updated since 2016 (i.e. over seven years ago).