Gecko has supported fractional pixel values for years in general, though for borders in particular the width is clamped to integer _device_ (not CSS) pixels.
WebKit has been rounding them at parse time (even in cases when 1 CSS px is multiple device pixels) for a while, but they're about to fix that.
I believe that IE also supports subpixel layout. Not sure about Opera, offhand.
Gecko has supported fractional pixel values for years in general, though for borders in particular the width is clamped to integer _device_ (not CSS) pixels.
WebKit has been rounding them at parse time (even in cases when 1 CSS px is multiple device pixels) for a while, but they're about to fix that.
I believe that IE also supports subpixel layout. Not sure about Opera, offhand.