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HTML

              
                <h1>Pure CSS scrolling shadows with <code>background-attachment: local;</code></h1>

<p><em><a href="http://lea.verou.me/2012/04/background-attachment-local/" target="_blank">Lea's approach</a>, but also applied to a horizontal scroll container (and using CSS Custom Properties)</em></p>

<h2>Vertical Scroll Container</h2>

<div class="scrollcontainer scrollcontainer--vertical">
  <div class="scrollcontainer__content">
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin consectetur sit amet ipsum eget aliquet. Suspendisse vitae lacinia ligula. Donec fringilla, nisl non pharetra ornare, metus nibh sagittis eros, vel porta mauris leo sodales quam. Nulla nec diam cursus, suscipit mauris quis, scelerisque felis. Duis sollicitudin nulla at libero porttitor, ut efficitur elit consequat. Morbi fringilla gravida ullamcorper. Cras vehicula sapien ac tellus scelerisque vehicula. Phasellus rhoncus sem eu ultricies aliquet. Suspendisse non justo at eros lacinia congue. Donec laoreet ultrices ultrices. Nulla velit velit, aliquet quis blandit sodales, suscipit scelerisque tortor. Donec non aliquet ipsum, sit amet tempus lorem. Pellentesque euismod suscipit ultricies.</p>
    <p>Nunc in blandit metus, sit amet iaculis nulla. Pellentesque lacinia diam sed enim gravida vehicula. Praesent ac nisi sit amet nisl sodales elementum. Etiam vitae nunc at nibh condimentum finibus non convallis mauris. Fusce pretium dui eu est fringilla, ut ultricies nunc euismod. Aliquam elementum cursus urna nec vehicula. Sed ac ligula velit. Morbi leo nulla, efficitur ut leo eget, porttitor egestas ex. Pellentesque viverra ligula interdum, fringilla magna eu, ultrices mi. Proin nulla quam, malesuada fringilla vulputate sit amet, condimentum et mauris. Etiam ante dolor, ultrices at lobortis in, iaculis sit amet eros.</p>
  </div>
</div>

<h2>Horizontal Scroll Container</h2>

<div class="scrollcontainer scrollcontainer--horizontal">
    <div class="scrollcontainer__content">
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin consectetur sit amet ipsum eget aliquet. Suspendisse vitae lacinia ligula. Donec fringilla, nisl non pharetra ornare, metus nibh sagittis eros, vel porta mauris leo sodales quam. Nulla nec diam cursus, suscipit mauris quis, scelerisque felis. Duis sollicitudin nulla at libero porttitor, ut efficitur elit consequat. Morbi fringilla gravida ullamcorper. Cras vehicula sapien ac tellus scelerisque vehicula. Phasellus rhoncus sem eu ultricies aliquet. Suspendisse non justo at eros lacinia congue. Donec laoreet ultrices ultrices. Nulla velit velit, aliquet quis blandit sodales, suscipit scelerisque tortor. Donec non aliquet ipsum, sit amet tempus lorem. Pellentesque euismod suscipit ultricies.</p>
    <p>Nunc in blandit metus, sit amet iaculis nulla. Pellentesque lacinia diam sed enim gravida vehicula. Praesent ac nisi sit amet nisl sodales elementum. Etiam vitae nunc at nibh condimentum finibus non convallis mauris. Fusce pretium dui eu est fringilla, ut ultricies nunc euismod. Aliquam elementum cursus urna nec vehicula. Sed ac ligula velit. Morbi leo nulla, efficitur ut leo eget, porttitor egestas ex. Pellentesque viverra ligula interdum, fringilla magna eu, ultrices mi. Proin nulla quam, malesuada fringilla vulputate sit amet, condimentum et mauris. Etiam ante dolor, ultrices at lobortis in, iaculis sit amet eros.</p></div>
</div>

<p><em>Source: <a href="https://www.bram.us/2019/10/24/pure-css-scroll-shadows-vertical-horizontal/" target="_top">https://www.bram.us/2019/10/24/pure-css-scroll-shadows-vertical-horizontal/</a></em></p>
              
            
!

CSS

              
                body {
  background: white;
  font-family: sans-serif;
  text-align: center;
  padding: 1em;
}

.scrollcontainer {
  margin: 0 auto;
  height: 10em;
  width: 40em;
  border: 1px solid #ccc;
  
  --background-color: rgba(255, 255, 255, 1);
  --shadow-color: rgba(34,34,34, 0.5);
  --shadow-size: 0.75em;
  --transparent: rgba(255, 255, 255, 0); /* We can't use "transparent" directly, because Safari would interpret the color as "transparent black" (see https://css-tricks.com/thing-know-gradients-transparent-black/). Using this workaround, it works fine. */
}

.scrollcontainer__content {
  padding: 0 1em;
  text-align: left;
}

.scrollcontainer--vertical {
  overflow-y: scroll;

  background: 
    linear-gradient(var(--background-color), var(--background-color), var(--transparent) calc(var(--shadow-size) * 2)),
    radial-gradient(farthest-side at 50% 0, var(--shadow-color), var(--transparent)),
    linear-gradient(to top, var(--background-color), var(--background-color), var(--transparent) calc(var(--shadow-size) * 2)),
    radial-gradient(farthest-side at 50% 100%, var(--shadow-color), var(--transparent)) 0 100%;
  background-color: var(--background-color);
  background-repeat: no-repeat;
  background-attachment: local, scroll,local,  scroll;
  background-size: 100% 100%, 100% var(--shadow-size), 100% 100%, 100% var(--shadow-size);
}

.scrollcontainer--horizontal {
  overflow-x: scroll;

  background:
    linear-gradient(to right, var(--background-color), var(--background-color), var(--transparent) calc(var(--shadow-size) * 2)),
    radial-gradient(farthest-side at 0 50%, var(--shadow-color), var(--transparent)),
    linear-gradient(to left, var(--background-color), var(--background-color), var(--transparent) calc(var(--shadow-size) * 2)),
    radial-gradient(farthest-side at 100% 50%, var(--shadow-color), var(--transparent)) 100%;
  background-color: var(--background-color);
  background-repeat: no-repeat;
  background-attachment: local, scroll, local, scroll;
  background-size: 100% 100%, var(--shadow-size) 100%, 100% 100%, var(--shadow-size) 100%;
  height: 100%;
}

.scrollcontainer--horizontal .scrollcontainer__content {
  white-space: nowrap;
}



h2, div + p {
  margin-top: 4em;
}
              
            
!

JS

              
                // Fix for Mobile Safari that doesn't correctly re-render backgrounds during scroll
// @ref https://bugs.webkit.org/show_bug.cgi?id=181048
// Alternative fix, using only CSS: https://codepen.io/bramus/pen/RwgXxJv
if (CSS.supports("-webkit-overflow-scrolling: touch")) {
  document.querySelectorAll(".scrollcontainer").forEach((scroller) => {
    scroller.addEventListener("scroll", () => {
      scroller.style.setProperty("--force-paint", Date.now());
    });
  });
}

              
            
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