[nitrogen]

Just a heads up, I saw no datepickers in Firefox 26. Here are the JS errors from the console:

    Blocked loading mixed active content "http://jonthornton.github.io/jquery-timepicker/jquery.timepicker.js"[Learn More] Datepair.js
    Blocked loading mixed active content "http://jonthornton.github.io/jquery-timepicker/jquery.timepicker.css"[Learn More] Datepair.js
    Blocked loading mixed active content "http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/themes/ui-lightness/jquery-ui.css"[Learn More] Datepair.js
    TypeError: $(...).timepicker is not a function Datepair.js:95
    TypeError: $(...).timepicker is not a function Datepair.js:153
    TypeError: $(...).timepicker is not a function Datepair.js:205
    TypeError: $(...).timepicker is not a function Datepair.js:248
    TypeError: $(...).timepicker is not a function Datepair.js:403

It looks like HTTPS Everywhere is switching to https://, so you just need to change some http:// URLs to protocol-relative URLs (starting with "//").

Hope this helps.