message: fix(masthead): ensure overlay does not scroll
  A fix to `<dds-left-nav-overlay>` to ensure that it won't move upon
  `<body>`'s scroll.
diff: &[active] {
  @extend .#{$prefix}--side-nav__overlay-active;
  + position: fixed;
  +
  // Makes the trigger button work without making it floated. In this way, we don't have to adjust the position of the logo
  top: 0;
  left: 0;
  