app/src/main/res/drawable/theme_gradient.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape>
<gradient android:angle="90" android:endColor="#e4bc1b" android:startColor="#ecd05f" android:type="linear" />
</shape>
</item>
</selector>