Overflow problem

[applibs]

When I use in browser zoom to 125% for example on some items I see part of another item on last pixel line. Its due sprite is calculated in percent like this: background-position: 15.384615384615385% 97.29729729729729%; and browser will wrong recalculate it. I tried use this config:

shape: {
            spacing: {
                padding: 2
            }

        },

but it is also problem because items are bigger of 4 pixels. When I used png sprites in the past I used margin to 4px and it was fixed well.
Can you improve this tool to generate spite with margin?