You don’t have a button called ‘donate’ but you do have an image in an anchor and the image has a filename called donate.png. is this the donate button you mention?
However you do have an actual button element on the page but that button is not called donate but has text that says “See The Project”.
Which one are you referring to and which one should be aligned with which :?
Note that the donate.png is an image and you can’t change the background color of that image because its an image. You’d have to swap it for another image.
Also note (and I have mentioned this before) that the following is invalid and unlikely to work cross browser.
<a href="https://test.be/"><button>See the Project</button></a>
You cannot nest a button element inside an anchor (or vice versa). Both have distinct purposes. It would be like nesting a link inside a link or a button inside a button. It’s nonsense as far as html is concerned.
Lastly note that the center tag was deprecated about 20 years ago and should not be used (theoretically (although unlikely) it could stop working at any time). You should instead use CSS to centre elements as required.
e.g. remove the center tag and centre the anchor holding the image.
.blockoPayBtn{
display:table;
margin:auto;
}
If you can clarify all the above then I will be glad to advise a course of action