1px white-space horizontal line appearing above/below various elements

[NeoGenet1c]

Mostly noticeable in IE11 where this sometimes happens between a homepage banner AND header strip.

It's always dependent on the height of content images (~ banner image) combined with the thickness of borders.

The most probable cause is the em/rem -> pixel fractions rounding that is implemented differently in every browser. And in some browsers, IE including, this rounding leaves a white 1px space line between an element and a border (instead of re-rendering the UI and positioning the element right behind/before a border).

Because of this, there's a chance to possibly find a hack that would enforce the correct rendering and removed the obsolete 1px space.