* Adding base styles for collapsed nav menu.
* Handling varying behaviour on mobile-sized screens, with the menu overlaying content instead of shrinking the content area.
* Folding the menu by default on screen sizes less than 960px, and if that condition is met after an orientation change
* Refactoring logic from Header/index.js to flag if user has scrolled to apply shadow to folded navigation as well.
* Refactoring styles in navigation feature to allow them to be loaded properly with webpack (with imports/etc).
Fixeswoocommerce/woocommerce-admin#4732
This updates `@wordpress/base-styles`, and because `@wordpress/components` depends on variables from it, that must be updated as well.
There are 3 major changes required as part of updating:
1. The $theme-color variable is no longer exposed by base-styles. Instead there are 3 css vars exposed. These are made available by use of a provided mixin. Situations where $theme-color was darkened using scss have been mapped as best as possible to the 2 other darkened shades of the css var that are available such as `--wp-admin-theme-color-darker-20` and `--wp-admin-theme-color-darker-10`. In some cases this means the colors are not exactly the same as before.
2. The post css `theme()` call is no longer available. All uses of this have been consolidated to use of the main theme css var `--wp-admin-theme-color`. This means that calls like `theme(secondary)` or `theme(outline)` etc have all been consolidated to the one color.
3. Many of the variables used for different shades of gray have been deprecated. These have been mapped across to the new gray variables. (Mapped according to the list described in woocommerce/woocommerce-admin#4732)
* Add base nav component
* Check if current screen is WC registered page
* Add core menu items
* Add param for menu items to migrate and hide old menu items
* Add body classes for wc navigation
* Check capability before adding menu items
* Add submenu items to frontend component
* Hide wc nav behind option
Co-authored-by: Joshua Flowers <joshuatf@gmail.com>
Joel Thiessen
Joshua T Flowers
Sam Seay
Ron Rennick