The Infinite Marquee

Posted on August 6, 2022
Takes about 6 minutes to read

The deprecated tag

The HTML <marquee> element had blessed (cursed?) the early days of the internet with the ability to insert scrolling text onto a webpage. It even included options to control text behavior once it reached the end of its container with a handful of attributes. Review them here on MDN if you're curious. Also, when visiting that MDN link, notice the page starts with a deprecation warning that this feature is no longer recommended:

Avoid using it, and update existing code if possible [...] Be aware that this feature may cease to work at any time.

A handful of usability concerns led to <marquee> eventually being nixed. They can be too distracting, don't respect reduced-motion preferences, and in most cases render text unreadable. Things get really out of hand if there are multiple <marquee> visible on screen like this example from MDN.

Fun? Maybe. But maybe don't do that.

A modern approach

Now that we've gleaned a tiny slice of web history, it's arguable that a marquee-style animation can inject some pop to a page when done responsibly. Developers have discovered a few ways of reimagining the concept, the most popular accomplished with HTML and CSS. In this scenario, content is duplicated to create the illusion of it looping indefinitely. Here's a stripped-down example:

<div class="marquee">
  <ul class="marquee__content">
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>
  <!-- Mirrors the content above -->
  <ul class="marquee__content" aria-hidden="true">
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>

The marquee concept has been done plenty of times and may seem old hat. However, most of the examples I came across weren't fully responsive. Many rely on a fixed-width parent or having enough elements to overflow the container for a seamless loop. What if, when the parent container is wider than the content overflow, the items spread themselves out so that the loop works at any size? I experimented with a few ideas to see what's possible in making this concept more flexible.

Here are the responsive styles that correspond to the HTML code block above:

.marquee {
  --gap: 1rem;
  display: flex;
  overflow: hidden;
  user-select: none;
  gap: var(--gap);

.marquee__content {
  flex-shrink: 0;
  display: flex;
  justify-content: space-around;
  min-width: 100%;
  gap: var(--gap);

To get a better sense of what's happening, open up this CodePen demo. Try turning each CSS rule off and on to see how it affects the marquee. Adjust the amount of items in the marquee's HTML. Watch how they spread out as the viewport widens or naturally overflow as it narrows.

Allow me to explain what this CSS is doing.

As items begin to overflow, gaps can be set to create room between each item. Gap values for the parent and child containers will need to match; Well that's a perfect case for defining a new CSS custom property! The gap: var(--gap) declaration supplies the space between each item when content overflows the parent plus space between the two child containers. This variable also comes in handy to offset the end position in the animation precisely:

@keyframes scroll {
  from {
    transform: translateX(0);
  to {
    transform: translateX(calc(-100% - var(--gap)));

Without including var(--gap) in this calculation, there would be a visible misalignment when the animation loops. Try updating the value to translateX(-100%) to see the issue.

The appearance of an infinite loop happens by animating the first child container completely out into the overflow while simultaneously pulling the duplicate container all the way into view. When the animation restarts, the first container picks up where the last left off. The illusion is complete! Yet it's also neverending... 😮

Important considerations

Really examine the use case for a marquee. They can be incredibly distracting and disorienting when implemented poorly.

Welcome to the demo zone

Here are a couple of CodePen ideas I had thrown together while experimenting with marquee animations. The logo wall is especially fun, introducing reverse animations and the ability to toggle the axis for a vertical marquee.

Explore more resources

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