Displaying/not displaying a banner
Uncomment/comment line 3 of _includes/header.html.
Update $promo-banner-height in _sass/variables/dimensions.scss, see inlined comment in file.
In css/main.css, inside selector body header.bootstrap, update top. See inlined comment in file.
Make sure that the div with class promo-banner in _includes-promo-banner.html has attributes data-date and data-time, and that these are set in UTC+0.
There are countdowns in the banner that use the date and time above.
