Z-index CSS top widget area toolbar bug.

[paaljoachim]

Description

In the widgets screen when no widgets are present the widget toolbar is partly below the top toolbar.

Step-by-step reproduction instructions

Widgets screen.

1. Go to the widgets screen
2. Remove all widgets also inside the Inactive widgets area. Update/Save. Refresh.
3. Click the first widget area.
4. Notice the CSS index issue in the first widget area. The widget area toolbar is partly hidden by the top toolbar.

Expected behaviour

Having the widgets area pushed far enough down the page so the widget area toolbar would not be partly below the top toolbar.

WordPress information

• WordPress version: 5.6
• Gutenberg version: 9.8 RC.
• Are all plugins except Gutenberg deactivated? Yes
• Are you using a default theme (e.g. Twenty Twenty-One)? Yes

Device information

• Device: Desktop
• Operating system: OSX 10.15.6
• Browser: Chrome

Ps
Somewhat associated issue: #28186

[draganescu]

I'll close this in favor of #26261 as that toolbar should now show up.