Install gnome-accessibility-themes by entering the following commands in the terminal:
sudo apt update sudo apt install gnome-accessibility-themes
Description:
High Contrast GTK+ 2 theme and icons
This is the version of GNOME's standard HighContrast theme, for the GTK+ 2.x toolkit. An icon theme is also included. . The GTK+ 3.x version is already included in libgtk-3-0.
Version: 3.28-1ubuntu1
Section: gnome