The site works in Firefox.
I thought that might be the case.
I think you have a custome css file in your colors theme (mystyle.css). Add the following lines to it, then clear your browser cache and refresh the page.
This ‘might’ help in Safari, but may also break Firefox. If so I can find a better solution at next release.
/* flex adjustments */
body {
height: initial;
min-height: initial;
display: block;
}
#content {
flex: none;
ms-flex: none;
-webkit-flex: none;
}