To show a load image while we address, save or update, we have the CSS styles that we can give according to our taste and need.
So in this example I would be applying it within a blank application, which will contain a style with animations inside it.
So, what we are going to do first is create a style for a class that is going to be called preloader_3, that inside it to start we will define the initial location within the screen.
Once the class or object is created, and when giving it a style, then we proceed to indicate the same class but in the Before event we will be indicating the format that our object will have with the animation that should be created with the @keyframes:
Finally we created the last event that would be "After":
With its respective animation: