On browser running on Mac, as well as mobil browsers, you can overscroll (aka the pulling down the top motion on mobile). This leads to an artefact where you have some extra white on the top (or the bottom, as you can also overscroll downward).

Luckily this is trivial to fix! Simply set the background color for the html tag:

html {
    body: black;
}

You can read more about it at: https://peter.coffee/htmls-background-color

It is easier to click that selecting comby.dev and opening it with a context menu.