older browsers

[jmbott]

testing for compatability
warning of incompatability

Refs:
https://www.browserstack.com/
https://stackoverflow.com/questions/830383/need-help-with-ie-6/6847170#6847170
https://www.garmahis.com/ie6-update-warning/
https://github.com/browser-update/browser-update/
https://stackoverflow.com/questions/15056620/jquery-check-if-browser-is-ie

[jmbott]

https://docs.travis-ci.com/user/browserstack/
https://docs.travis-ci.com/user/deployment/pages/
https://help.github.com/en/github/authenticating-to-github/creating-a-personal-access-token-for-the-command-line

[jmbott]

https://github.com/micahgodbolt/travis-browserstack-demo
https://jekyllrb.com/docs/continuous-integration/travis-ci/

[jmbott]

notify of outdated browser detect,
ie comments:
https://www.quirksmode.org/css/condcom.html