Scrollable CSS overlay

Apr 1, 2017 15:49 · 229 words · 2 minutes read css overlay scrolling

I recently had the need to create a CSS overlay for the search function on this site. My requirements were that the overlay should be scrollable, whilst the overlay was visible the body should not be scrollable, and any HTML for the overlay should be after the main content.

I first tried adding overflow: hidden to the body when the overlay was shown using JavaScript but this has the effect of scrolling the body and main content immediately to the top, giving a jarring user experience when the overlay is dismissed.

Then I hit upon this solution which was almost what I wanted, except that the overlay had to come before the content in the HTML.

Adding z-index:1 to the overlay style gave me the perfect solution for my use-case.

HTML

<body>
  <div id="main"></div>
  <div id="overlay">
    <div class="overlay-content"></div>
  </div>
</body>

CSS

html, body {
  height: 100%;
}

#main {
  height: 100%;
  overflow: auto;
  -webkit-overflow-scroll: touch;
}
               
#overlay {
  position: fixed;
  top: 0px;
  left: 0px;
  right: 0px;
  bottom: 0px;
  z-index: 1;
  background-color: rgba(0, 0, 0, 0.8);
}

.overlay-content {
  height: 100%;
  overflow-y: scroll;
}

I don’t particularly like having the extra .overlay-content div or having to wrap my content in a div, but it’s probably the best I’m going to get with CSS for now.

You can see the overlay in action by using the search functionality on this site.

© Copyright 2017 Joseph Earl

Search