animation-range-start

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

The animation-range-start CSS property sets the point on the timeline where an animation should start.

Syntax

css

/* Keyword or length percentage value */
animation-range-start: normal;
animation-range-start: 20%;
animation-range-start: 100px;
/* Named timeline range value */
animation-range-start: cover;
animation-range-start: contain;
animation-range-start: cover 20%;
animation-range-start: contain 100px;
/* Global values */
animation-range-start: inherit;
animation-range-start: initial;
animation-range-start: revert;
animation-range-start: revert-layer;
animation-range-start: unset;

Values

normal: Represents the start of the timeline. This is the default value.
<length-percentage>: Specifies a length or percentage value measured from the beginning of the timeline.
<timeline-range-name>: Specifies a named timeline range within the overall timeline. The range starts at 0%.
<timeline-range-name> <length-percentage>: Specifies a length or percentage value measured from the beginning of the specified named timeline range.

Allowed values for the animation-range-start property are normal, a <length-percentage>, a <timeline-range-name>, or a <timeline-range-name> followed by a <length-percentage>. If the <timeline-range-name> value does not include a <length-percentage>, the percentage defaults to 0%. See animation-range for a detailed description of the available values. Also check out the View progress timeline visualizer, which shows what the different values mean in an easy-to-follow visual format.

The animation-range-start is included in the animation shorthand as a reset-only value. This means that using the animation shorthand resets any previously declared animation-range-start value of equal or lower specificity to normal; the shorthand cannot be used to set a new animation-range-start value. When creating CSS scroll-driven animations, you should declare animation-range-start after declaring any animation shorthand to avoid resetting the value to normal.

The animation-range-start, along with the animation-range-end property, can also be set using the animation-range shorthand.

Formal definition

Initial value	`normal`
Applies to	all elements
Inherited	no
Percentages	Relative to the specified named timeline range if specified, otherwise relative to the entire timeline
Computed value	A list where each item may be 'normal', a length percentage, or a timeline range name and a length percentage
Animation type	Not animatable

Formal syntax

animation-range-start = 
 [ normal | <length-percentage> | <timeline-range-name> <length-percentage>? ] # 

<length-percentage> = 
 <length> | 
 <percentage>

Examples

Creating a scroll view progress timeline with range start

In this example, the animation-range-start is applied to an element animated via a scroll progress timeline. This makes the animation start well before the element enters the scrollport.

HTML

<div class="content">
 <h1>Content</h1>
 <p>
 Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
 tempor incididunt ut labore et dolore magna aliqua. Risus quis varius quam
 quisque id. Et ligula ullamcorper malesuada proin libero nunc consequat
 interdum varius. Elit ullamcorper dignissim cras tincidunt lobortis feugiat
 vivamus at augue.
 </p>
 <p>
 Dolor sed viverra ipsum nunc aliquet. Sed sed risus pretium quam vulputate
 dignissim. Tortor aliquam nulla facilisi cras. A erat nam at lectus urna
 duis convallis convallis. Nibh ipsum consequat nisl vel pretium lectus.
 Sagittis aliquam malesuada bibendum arcu vitae elementum. Malesuada bibendum
 arcu vitae elementum curabitur vitae nunc sed velit.
 </p>

In the middle of a long block of text, we've included an element that we'll animate. We've added a lot of text to ensure that the content overflows its container; the extra text is hidden here for brevity.

html

<div class="animatedElement"></div>

<p>
 Adipiscing enim eu turpis egestas pretium aenean pharetra magna ac. Arcu
 cursus vitae congue mauris rhoncus aenean vel. Sit amet cursus sit amet
 dictum. Augue neque gravida in fermentum et. Gravida rutrum quisque non
 tellus orci ac auctor augue mauris. Risus quis varius quam quisque id diam
 vel quam elementum. Nibh praesent tristique magna sit amet purus gravida
 quis. Duis ultricies lacus sed turpis tincidunt id aliquet. In egestas erat
 imperdiet sed euismod nisi. Eget egestas purus viverra accumsan in nisl nisi
 scelerisque. Netus et malesuada fames ac.
</p>
</div>

CSS

A scroll progress timeline is defined using setting a scroll() function as the value of the animation-timeline property. This is declared after the animation shorthand to avoid resetting the longhand property value.

We've also set animation-range-start to make the animation start earlier than expected.

css

.animatedElement {
 background-color: deeppink;
 animation: appear 1ms linear;
 animation-timeline: scroll();
 animation-range-start: -25%;
}
@keyframes appear {
 from {
 background-color: rebeccapurple;
 opacity: 0;
 transform: scaleX(0);
 }
 to {
 background-color: darkturquoise;
 opacity: 0.75;
 transform: scaleX(0.75);
 }
}

Other styles applied in this example have been hidden here for brevity.

.animatedElement {
 height: 200px;
 margin: 0 auto;
 background-color: deeppink;
}
.content {
 width: 75%;
 max-width: 800px;
 margin: 0 auto;
}
p,
h1 {
 font-family: "Helvetica", "Arial", sans-serif;
}
h1 {
 font-size: 3rem;
}
p {
 font-size: 1.5rem;
 line-height: 1.5;
}
@supports not (animation-range-start: normal) {
 body::before {
 content: "Your browser does not support the 'animation-range-start' property.";
 color: black;
 background-color: wheat;
 display: block;
 text-align: center;
 padding: 1rem 0;
 }
}

Result

Scroll to see the element animate. Notice how the element is already scaled and semi-opaque as it enters the viewport. This is because the element started animating well before it entered the viewport.

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