Hover Styling Error on Selected Chapter with Dropdown Menu

[mikeengland]

In the Handbook on pages that have chapter menus I noticed that while hovering over an active chapter, that has a drop down, the top level menu item white text on a white background while hovering.

Example Page:
​https://make.wordpress.org/docs/handbook/developer-resources/
If you select "Developer Resources" in the chapters menu and then hover over it the effect should be recreated.

Current Styling

.menu-table-of-contents-container > ul > li.open > div > a:hover {
    color: #fff;
}

Simple Fix

.menu-table-of-contents-container > ul > li.open > div > a:hover {
    color: #fff;
    background-color: #0073aa;
}

[mikeengland]

Example hover state on menu item with children.

[coffee2code]

In 6430:

Breathe: Fix chapters menu item background color on hover.

Props mikeengland.
Fixes #3400.