Mar 28, 2019 - 06:36 AM
Thank you for contacting Biobidet Support.
This particular unit will yes lay on top of your toilet porcelain. The white rubber o-rings are simply to protect the toilet again possible scratches. These o-rings are layed down first then the bidet with the mounting brackets, the existing toilet seat ring and lids after that and secure those bolts and tighten down.
You can try and remove the rubber white o-rings as you will more than likely not get any screatches to your toilet to see if this helps close the gap a bit. You can also purchase if you wish "shims" from any local hardware store if you wish. These can be placed under the back of the bidet body between where the squares that hold the mounting brackets are located. I have provided a link to a home depot for :shims" for your reference.
Source: A3 Mounting