Please tell me, with the help of which you can implement the blur effect. You must implement so that under the block content menu blurred. The menu let's say your background: rgba(32, 32, 32, 0.6), and all that under the unit is another content. And need to the fact that under the menu block eroded.
Need such as pages, where the header bar https://iamvdo.me/en/blog/advanced-css-filters:
This is not an option because of bad support