Applying CSS Glass/Blur Effect to an Overlay

Q: Implementing a blur effect on a semi-transparent overlay

A web developer is facing difficulties in applying a blur effect to an overlay div, making the content behind the div appear blurred.

Previous Attempt:

The developer attempted to implement the effect using the following CSS:

#overlay {
    filter:blur(4px);
    -o-filter:blur(4px);
    -ms-filter:blur(4px);
    -moz-filter:blur(4px);
    -webkit-filter:blur(4px);
}

However, this approach was unsuccessful.

Revised Solution:

For a simpler and more modern solution, the developer can utilize the backdrop-filter property:

#overlay {
    backdrop-filter: blur(6px);
}

Browser Support:

Note that browser support for backdrop-filter is not comprehensive. However, for many use cases, a blur effect is not critical.