> "The `opacity` property in CSS defines the transparency level of an element. A value of `1` means fully visible; a value of `0` makes it completely transparent. When used in a hover state, such as `a:hover { opacity:
0; }`, it causes the element to fade out when hovered over."
>
> "Unlike `visibility: hidden`, which hides the element but retains its space in the layout, `opacity` allows for smooth visual transitions in transparency." References:
* MDN Web Docs: opacity
* CSS Visual Effects Module Level 1
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