message: feat(theme): update navbarHeight
diff: /* layout */
  // navbar
  -$navbarHeight: 4.5rem !default;
  +$navbarHeight: 4rem !default;
  $navbarHorizontalPadding: 1.5rem !default;
  $navbarVerticalPadding: 0.7rem !default;
  $navbarMobileHeight: 3.25rem !default;
  