CSS Opacity

The opacity property specifies the opacity/transparency of an element.

Transparent Image

The opacity property can take a value from 0.0 to 1.0. The lower value, the more transparent.

Transparent Hover Effect

The opacity property is often used together with the :hover pseudo-class to change the opacity on mouse-over.

Transparency using RGBA

When using the opacity property to add transparency to the background of an element, all of its child elements inherit the same transparency. This can make the text inside a fully transparent element hard to read. If you do not want to apply opacity to child elements, use RGBA color values instead.