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HTML

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CSS

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CSS Base

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JavaScript

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Babel includes JSX processing.

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HTML 

              
                <!-- odpowiedź na https://forum.pasja-informatyki.pl/499608/nakladanie-blur-na-elementy-css -->

<div class="blured-wrapper"></div>

<!-- Treść strony -->

<article>
  <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit. Magni suscipit sed soluta alias eos quo possimus, fugit molestias ratione, laudantium autem ullam commodi tempora fuga id tenetur quidem. Neque, recusandae!</p>
  <p>A recusandae distinctio fuga dicta obcaecati explicabo? Eaque dicta quod nam, distinctio voluptas eveniet. Fugit magnam sed quia harum consectetur deserunt nesciunt. Hic possimus perspiciatis omnis corrupti blanditiis sunt debitis.</p>
  <p>Consequatur eligendi libero sapiente aliquam culpa soluta quidem numquam illo nisi enim, debitis delectus? Necessitatibus est quisquam optio vitae provident dicta iure dolores vel saepe illum, autem molestias, expedita sint.</p>
  <p>Earum autem labore recusandae, sequi debitis quo quisquam ad mollitia omnis tempora error cupiditate quae atque accusamus qui exercitationem quaerat non enim in esse itaque culpa laboriosam. Numquam, rerum odit.</p>
  <section class="content-without-blur">
  Ten element jest bez blura :)
</section>
  <p>Vel, dolorem? Ratione, atque nihil dolorem libero temporibus in incidunt sit ex reiciendis quisquam praesentium, eligendi et odit labore illum quasi velit recusandae cupiditate, dolores blanditiis nemo quos alias? Mollitia!</p>
  <p>Illo perferendis cupiditate nulla, omnis voluptatibus deleniti magnam a recusandae minus necessitatibus ut earum odit in voluptatum corporis aperiam sunt, nemo eveniet autem voluptates. Ipsa recusandae nisi rem error. Quia?</p>
  <p>Commodi ipsum debitis laboriosam possimus cumque nam alias aperiam, accusamus libero veritatis minima dolorum veniam doloremque earum soluta magni voluptatem suscipit iure eveniet culpa. Beatae culpa quidem ratione sunt suscipit?</p>
  <p>Error voluptate repellendus adipisci magnam sapiente porro molestiae. Perferendis sit, voluptates provident atque quod similique quaerat tempora incidunt saepe, cumque eius commodi quae ad in. Blanditiis nesciunt itaque quam dicta.</p>
  <p>Aut suscipit a facere doloribus voluptatibus. Dicta laboriosam architecto officia illo reprehenderit eius at est, delectus ducimus veritatis sapiente! Autem expedita perspiciatis consequuntur, assumenda aperiam velit laborum nam dolor exercitationem!</p>
  <p>Voluptatibus enim, illum error ratione necessitatibus eveniet at debitis? Iste mollitia quidem corrupti quasi iusto ducimus accusantium, beatae deserunt velit nam culpa libero sunt, soluta vitae quos a incidunt repellat!</p>
  <p>Nam amet modi voluptate delectus similique pariatur vitae magnam, voluptates nemo iusto accusantium in consequatur neque cumque eius deserunt assumenda ut cum architecto omnis. Molestias quos dolorum eos aliquam accusantium!</p>
  <p>Rerum cum ipsam modi repudiandae itaque vel tempora adipisci nemo quam exercitationem nulla, ab eum velit iste corporis molestias at ullam quasi sed enim repellendus magnam nisi unde voluptatum. Aut?</p>
  <p>Quae esse, expedita hic perspiciatis ea dolore blanditiis reiciendis maxime asperiores ipsa aut a autem laborum rerum molestiae facere, numquam, molestias inventore ullam. Harum, provident dicta. Qui deserunt animi officiis?</p>
  <p>Molestiae facere adipisci placeat sapiente harum corporis? Consequuntur eaque quaerat numquam nihil ipsum neque modi repudiandae, deserunt, iste aspernatur quae labore expedita est eveniet dolor a. Ea mollitia facilis animi.</p>
  <p>Eligendi necessitatibus ut quidem! Reprehenderit laudantium iure eos iusto cum esse alias laborum sunt expedita illo. Quisquam ea dicta nisi laboriosam ipsum aliquid vel cumque necessitatibus optio deserunt. Consequuntur, facilis!</p>
  <p>Exercitationem, praesentium vitae vel, quia odio autem obcaecati beatae ut quis qui libero, distinctio aspernatur facilis voluptates! Itaque velit rem cum soluta nihil quod nostrum, blanditiis ullam modi porro qui!</p>
  <p>Eaque sapiente, repudiandae ut porro commodi aspernatur velit quas ad quaerat, aut iste maxime animi maiores sed dignissimos nostrum quisquam voluptatibus consequatur labore, vel tempore corporis. Aspernatur architecto explicabo autem.</p>
  <p>Cum enim sapiente voluptates ratione, maxime totam sed accusantium similique! Accusantium possimus voluptates natus. Eos, impedit dolore iste, aspernatur ipsam aliquam, magnam repellat laborum labore natus cumque quasi aliquid facere.</p>
  <p>Tenetur consequuntur quis fugit assumenda possimus? Iste dolor praesentium vel delectus dolorem ullam natus ducimus eius quasi? Atque, eaque. Veniam voluptatum aperiam ut! Ad ducimus ut eius excepturi facere saepe.</p>
  <p>Temporibus eos reiciendis aut maxime recusandae at voluptate natus doloremque deserunt repellendus! Pariatur ab itaque molestiae possimus aliquid, fuga dolorum, ipsa, at praesentium quam nam reiciendis sit repudiandae sed voluptatem?</p>
</article>
!

CSS 

              
                .blured-wrapper {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,.4);
  backdrop-filter: blur(4px);
  z-index: 9;
}

.content-without-blur {
  position: relative;
  z-index: 10;
  background: tomato;
  padding: 2rem;
}
!

JS
!
999px

Console