The navbar, when 'stuck' at the top, mixes up with the middle column which is also white. A border-bottom or a box-shadow would add a line of contrast and make it easy on the eye. I tried box-shadow, and it worked fine while the navbar was 'stuck' at the top, but it looked bad when in its normal position. You could play around to see what works best. But as of now, I think a line of contrast is clearly needed at the bottom of the navbar.
The navbar, when 'stuck' at the top, mixes up with the middle column which is also white. A border-bottom or a box-shadow would add a line of contrast and make it easy on the eye. I tried box-shadow, and it worked fine while the navbar was 'stuck' at the top, but it looked bad when in its normal position. You could play around to see what works best. But as of now, I think a line of contrast is clearly needed at the bottom of the navbar.