I like to keep all the instance form colours different from each other so that I can easily tell them apart. Set the following profile option to any colour of your choice.
Set the Java Look and Feel profile option value to oracle. If you set it to generic, it will take the default values and you won’t be able to set your own color.
Nav : System Administrator àProfile àSystem à Java Look and Feel
2. Then set Java Color Scheme profile option value to any of the LOVs as per your choice.
Navi : System Administrator àProfile àSystem à Java Color Scheme
The different colours are,