Set single '1' in inline div with Arial font-family and 16px font size. The offset width of div is 9px. When I insert '11' in that same div, it should give me 18px offset width. It gives me 17px offset width. So i think it is due to overlapping of digit '1'. And this happens only for digit '1'. Div gives me proper offset width for all other digit in Arial font-family. Div gives me proper offset width for other font family too. This bug is with only '1' digit in Arial font-family. JsFiddle link to test. http://jsfiddle.net/De6Ru/3/

This is not a bug. The Arial font includes a kern pair that reduces the spacing between adjacent "1" glyphs. See more detailed discussion in bug 931029.

Thanks for reply, Jonathan. I've got a solution from comment( John Daggett (:jtd) Comment 8 ) of bug 931029. Explicitly disable kerning works like charm for me.