Not all blues and grays have been updated

[helen]

We seem to have missed some spots outside of the admin, like media and wp_die(). Previously: #31234

[helen]

I'm already knee-deep in this, just using this for tracking.

[helen]

In 35327:

wp_die(): Update colors and button styling.

see #34388, #31459.

[helen]

In 35330:

Media: Update colors to match the times.

This bikeshed is a real nice blue.

props afercia.
fixes #34244. see #34388.

[helen]

In 35340:

RIP #21759b, the old WordPress Blue.

The final lingering instances were all for hidden accessibility helper text.

fixes #34388.