you could place the background circles as background images in the body, since they're not content but decorative elements.
the positioning of the card itself could be done with display: flex; justify-content: center; and align items: center; I think this would be a better (or easier) solution, than the use of positioning absolute (my opinion 🤷♀️)
as you can see the report mentioned some html issues. You can use this validator to check your html and css: https://validator.w3.org/ I think it's pretty helpful because you not only see issues but the cause.