JoomDonation - custom donation button

I didn't see in the documentation if it's possible to customize a donation button.
would like to create a Pledge Button for a marathon IE. $donation per mile... we would probably charge a donation of $5.00 then rebill for the difference of money owed...
Is this possible... can I do it with a special button class or override?
or just charge a flat fee - and create it as a one time recurring charge that we can edit the second payment for balance owing.
Not sure how to tackle this... every thing else seems like a perfect fit

Hi Ron,
Joom Donation has various modules, in your case, you can use module: "Donation", it will show how pre-definded amounts and "Donate" button. Thus, user will able to select donate amount and click on button: "Donate" to pay money.
You are also can use plugin: "Load Module" of Joomla to load content of this module to specific Joomla article.
If you have any further questions, please let me know.
Thanks
Dam