Thanks for the fix, but I should mention if anyone else has this problem that the CSS property to look for is different to the one provided.

You will find the CSS property to change inside the general.css file inside:

/components/com_booking/assets/css/general.css

Then the CSS property to look for is:

.payments .payment {}

There is no #adminForm in front.

Once I added the float property it worked fine.

Hope this helps.