How to get rid of scrolls?

Question

JavaScript

The chances that the same person will view the topic twice are very small,
so I did not update the previous one.
Here is a clear example of "non-residential scrolls" .
How to competently get rid of them without introducing elusive values ​​into the code, such as - here a little bit and there more?
UPD:
Do browsers have some kind of unspoken indent from the origin?
If so, how far does it retreat?

Answer 1

Set the canvas element to display: block

Answer 2

set width and height to 100% ?

Answer 3

In css to prescribe overflow:hiddenfor body?
But then part of the canvas will not be visible