bug: Dark Theme: Toolbar and item-background colors doesn't follow the MD

[al1991i]

Bug Report

Ionic version: [x] 5.x

Current behavior:

1. The toolbar on MD uses --ion-background-color: #121212.
2. The value of --ion-item-background is #1A1B1E

Expected behavior:

Based on MD documentation

1. The toolbar on MD should use --ion-item-background instead of --ion-background-color: #121212.
2. The value of --ion-item-background should be #1d1d1d instead of #1A1B1E

Steps to reproduce: Check the MD CSS provided in Ionic Dark Theme section from this Ionic Documentation

Thanks.