This property sets the canvas to a full window size acting like a background, the most common configuration. The default
value is true, so the canvas will be full screen acting like an animated background.
This is really helpful since there's no need to write CSS code to have a full size tsParticles instance.
This is the CSS z-index property set to the canvas, the default value is 0.
If the z-index is less than 0 the mouse interactions works only with the interactivity.detectsOn set to window.