As for the shape of the "shield", it is SVG that is placed in file rife\header-variants\horizontal-one-line.php line ~63, there you can find code: <svg version="1.1"
Yes, you overwrite default bg-color of marked items and that is why it happening. You will have to add such custom CSS .top-menu li:hover > a, .top-menu li.current-menu-item > a, .top-m