Background / text color input field

[ubuntutest]

Hello,
even though this project is a bit old, i managed to implement it in my android app.
The other projects on github are too complex or are developed in kotlin, I needed a simple search written in java.

I can't change the menu background color and the input field text color, I also removed the name to the left of the magnifying glass icon, but it doesn't take up all the menu space. , remains centered: