Revert to Unity's old looks

The Unity version 7.6 changelog says that Unity now has new, more “modern” looks. For example, the HUD now doesn’t have gradient effects. I don’t like the changes. Is there any way to revert to how Unity used to look?

Hello,
Open a terminal and paste this line:
gsettings set org.gnome.desktop.interface gtk-theme Ambiance

Disconnect and reconnect your session.After that, you will find the classic theme.

That did change the taskbar, but the HUD still doesn’t change. I want it to look like this:
unity_ubuntu18.04-830x380

,but it looks like this:
Снимка от 2022-10-26 23-30-57