If you don't want to add a background colour to the body tag all you need to do is remove the padding from the featuredbg div and add a height value. You'll also need to add a height value to the main wrapper (holder) so that you maintain the height: 100% in css.
Code would be as follows:
#holder {
min-height: 100%;
height: 100%;
position: relative;
}
#featuredbg {
background: #453A7E;
border-top: 1px solid rgba(255, 255, 255, 0.2);
height: calc(100% - 110px);
}
The height value in featuredbg takes the 100% of the available space and minuses the height of your footer (menubg). If you just had 100% the footer would be ignored and the featuredbg would stretch past the footer.