The billing web page has a technical issue.

There is a css section that says:
.content {
margin-bottom:0;
margin-left:auto;
margin-right:auto;
margin-top:0;
min-height:556px;
width:780px;
}

Width 780 fails if I have font size 17 in firefox (turns out to be 17 pixel, not 17 point), and force my font size. (It works at 16).

While the 16 pixel (default) font size on the button is readable, the smaller (14) pixel font text really is not.

I don't know if you can actually get it to work with any user-preference font size, without forcing a specific one. I really don't like tiny fonts.