This property sets the canvas to a full window size acting like a background, the most common configuration. The default value is false since many already have different configurations.
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.
If the z-index is less than 0 the mouse interactions works only with the interactivity.detectsOn set to window.
The options to set the particles in the background using CSS
fixedposition The IFullScreen.zIndex property sets the background CSSz-indexproperty [[include:Options/FullScreen.md]]