Dual focus b/wn sticky header score gauge + highlighter

[connorjclark]

From: https://bugs.chromium.org/p/chromium/issues/detail?id=972504#c1

[brendankenny]

It seems like the focus ring is revealing the underlying problem of our dom structure being weird (having the highlighter be a child of the first score gauge instead of the sticky header). We put it there for convenience, but I wonder if we can fix it on that level, independent of styling changes?

[paulirish]

fixed by #9186