Is this a random number, 56.25%? Or what is it based on? Because the container div for a youtube iframe is 1 px too heigh (in desktop mode - havent tried other devices) thus revealing youtubes black background with 1 px. Setting it to 56.10% shrinks the container div in height but I don't know what other effects this will have?

Is this a known issue? Will/can it be fixed? Or is it by design? Can someone please clarify with some more details?