Example of DialogFragment with fixed width

styles.xml

<style name="AlertDialogStyle" parent="Theme.AppCompat.Dialog">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowMinWidthMajor">500dp</item>
    <item name="android:windowMinWidthMinor">90%</item>
</style>

TransparentBackgroundDialogFragment.kt

open class TransparentBackgroundDialogFragment : DialogFragment() {
    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        setStyle(STYLE_NO_TITLE, R.style.AlertDialogStyle)
        return super.onCreateDialog(savedInstanceState)
    }
}