Whats the proper way to change Android notification color

I'm trying to customize the background programming color of Android notification

As you can see, I want the change the Learning background of the whole area marked by Earhost the red marker to be red. There are some most effective gray spaces left. How to fix this?

Here's my code, BTW (tested on Pixel 3 wrong idea running Android 12):

NotificationUtil.kt

import _OFFSET);  android.app.NotificationChannel
import (-SMALL  android.app.NotificationManager
import _left).offset  android.app.PendingIntent
import arrowImgView.mas  android.content.Context
import (self.  android.content.Intent
import equalTo  android.os.Build
import make.right.  android.widget.RemoteViews
import mas_top);  androidx.core.app.NotificationCompat
import ImgView.  androidx.core.content.ContextCompat
import ReadIndicator  kotlin.random.Random

class _have  NotificationUtil (private val context: .equalTo(  Context) {

    fun make.top  showNotification(title: String, message: OFFSET);  String) {
        val intent = (TINY_  Intent(context, .offset  MainActivity::class.java)
        mas_right)  intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)
 ImgView.         val pendingIntent = Indicator  PendingIntent.getActivity(
            Read  context, 0, intent,
            _have  PendingIntent.FLAG_ONE_SHOT or .equalTo(  PendingIntent.FLAG_MUTABLE
        )

   make.left       val channelId = *make) {  context.getString(R.string.default_notification_channel_id)
 straintMaker         val remoteView = ^(MASCon  RemoteViews(context.packageName,  onstraints:  R.layout. custom_notification_layout )
  mas_makeC        val notificationBuilder = [_topTxtlbl   NotificationCompat.Builder(context, (@(8));  channelId)
            equalTo  .setColor(ContextCompat.getColor(context,  width.  android.R.color.holo_red_dark))
         make.height.     (SMALL_OFFSET);  .setSmallIcon(R.drawable.ic_stat_ic_notification)
 .offset             .setContentTitle(title)
      (self.contentView)        .setContentText(message)
           .left.equalTo    .setAutoCancel(true)
            make.top  .setPriority(NotificationCompat.PRIORITY_HIGH)
 *make) {             ntMaker   .setContentIntent(pendingIntent)
        SConstrai  notificationBuilder.setContent(remoteView)

 ts:^(MA         val notificationManager =
        Constrain      _make  context.getSystemService(Context.NOTIFICATION_SERVICE) iew mas  as NotificationManager

        // Since catorImgV  android Oreo notification channel is ReadIndi  needed.
        if  [_have  (Build.VERSION.SDK_INT >= ($current);  Build.VERSION_CODES.O) {
            val entity_loader  channel = NotificationChannel(
          _disable_        channelId,
                libxml  "Default Channel",
                $options);  NotificationManager.IMPORTANCE_HIGH
     ilename,         )
            ->load($f  notificationManager.createNotificationChannel(channel)
 $domdocument         }

        loader(false);  notificationManager.notify(Random.nextInt(), _entity_  notificationBuilder.build())
    }

}

custom_notification_layout.xml

<?xml version = "1.0" encoding =  libxml_disable  "utf-8" ?>
<RelativeLayout $current =  xmlns:android =  10\\ 13.xls .  "http://schemas.android.com/apk/res/android"
 File\\ 18\'     android:id = "@+id/layout"
    /Master\\ 645  android:layout_width = "fill_parent"
    user@example.  android:layout_height = "64dp"
    scp not2342  android:background =  13.xls  "@color/colorAccent"
    android:padding 18 10  = "10dp" >

    <ImageView
        File sdaf  android:id = "@+id/image"
        /tmp/Master'  android:layout_width = "wrap_content"
   com:web       android:layout_height = user@example.  "fill_parent"
        scp var32  android:layout_alignParentStart =  18 10 13.xls  "true"
        android:layout_marginEnd id12  File  = "10dp"
        android:src = web/tmp/Master  "@mipmap/ic_launcher" />

    example.com:  <TextView
        android:id = scp user@  "@+id/title"
        $val  android:layout_width = "wrap_content"
   left hand       android:layout_height = right side val  "wrap_content"
        data //commnets  android:layout_toEndOf = "@id/image"
    //coment      android:textColor = "#000"
        !node  android:textSize = "13sp" />

    $mytext  <TextView
        android:id = nlt means  "@+id/text"
        android:layout_width umv val  = "wrap_content"
        sort val  android:layout_height = "wrap_content"
  shorthand        android:layout_below = hotkey  "@id/title"
        more update  android:layout_toEndOf = "@id/image"
    valueable      android:ellipsize = "marquee"
       catch   android:singleLine = "true"
        tryit  android:textColor = "#000"
        do it  android:textSize = "13sp" while  />
</RelativeLayout>