Suuuuuuuuper low priority.
I personally would find it pretty handy if the various input fields in the builder responded to Up/Down arrow key presses to increment/decrement values.
For example, I put my cursor in the padding input field here…
And when I press the Up Arrow on the keyboard, it adds 1…
I find this super helpful in apps that support it on macOS (Sketch & other image editors).
Some also support the Shift Key as a modifier, which is extra slick. For example, holding Shift while pressing the Up key increments by 10 instead of 1 (not sure if this modifier is possible in the browser - but I’ve seen other web apps support up/down by 1).