Imagine the situation you want to change the color of the element you can't inspect the right way because of the script execution goes on the background of the website. So you can't catch it and find the correct Class or ID of the element that you wish to change the color for.
The solution would be to pause script execution. Press F12 or Control+Shift+I and use the following screenshots showing you the workaround =
After when you know the correct class/ID, go to your LiveAgent account dashboard -> Chat -> Chat buttons -> edit the desired chat button -> Chat window -> set custom CSS (the below one is an example but can be used)
.MessageNotification.MessageNotification-Unread.MessageNotificationTypeM {
background: #ffff00;
}
.chatMessagesGroupAgent .messagesPanel .MessageNotification.MessageNotification-Unread:first-child:before {
border-left-color: #ffff00;
}
And see the result below here ->
These instructions you can follow in case you have a similar case.