CSS 57 💻 animation properties part 2 - KandZ

This lesson covers the remaining animation properties: animation-fill-mode, animation-play-state, animation-timeline, and animation-composition.

Overview of Properties

Property	Description	Default
`animation-fill-mode`	Styles before/after animation	`none`
`animation-play-state`	Running or paused	`running`
`animation-timeline`	Timeline that controls the animation	`auto`
`animation-composition`	How multiple animations combine	`replace`

1. animation-fill-mode

Defines the styles applied to an element before and after the animation plays.

.box {
    animation-fill-mode: forwards;
}

Values

Value	Description
`none`	No styles applied outside the animation (default)
`forwards`	Keep the last keyframe’s styles after the animation ends
`backwards`	Apply the first keyframe’s styles during the delay
`both`	Apply both `forwards` and `backwards`

Visual Explanation

Without fill-mode:
[before] [animation] [after → reverts to original]

With forwards:
[before] [animation] [after → keeps end state]

With backwards:
[before → shows start state] [animation] [after]

With both:
[before → shows start state] [animation] [after → keeps end state]

Key Points:

forwards — the element stays at the animation’s end state
backwards — the element shows the start state during the delay
both — combines both effects
Without fill-mode, the element snaps back to its original state after the animation

2. animation-play-state

Controls whether an animation is running or paused.

.box {
    animation-play-state: paused;
}

Values

Value	Description
`running`	Animation is playing (default)
`paused`	Animation is paused

Key Points:

Useful for pausing animations on hover
The animation resumes from where it was paused
Commonly used with :hover for interactive control

Example:

.animation:hover {
    animation-play-state: paused;
}

3. animation-timeline

Allows you to specify a timeline that controls the animation instead of the default document timeline.

.box {
    animation-timeline: scroll();
}

Values

Value	Description
`auto`	Default document timeline (default)
`none`	No timeline — animation doesn’t play
`scroll()`	Binds animation to scroll position
`view()`	Binds animation to element visibility in viewport

scroll() Timeline

.box {
    animation-timeline: scroll();
}

The animation progresses in sync with scrolling — as the user scrolls, the animation advances. This creates scroll-driven animations that feel connected to the user’s interaction.

Variations:

animation-timeline: scroll();           /* Root scroller */
animation-timeline: scroll(root);       /* Root scroller */
animation-timeline: scroll(nearest);    /* Nearest scrollable ancestor */
animation-timeline: scroll(self);       /* The element itself */

view() Timeline

.box {
    animation-timeline: view();
}

The animation progresses based on the element’s visibility within the viewport — as the element enters, crosses, and exits the viewport, the animation plays.

Key Points:

animation-timeline is a modern feature with growing browser support
Scroll-driven animations are performant — they run on the compositor thread
Always provide a fallback for browsers that don’t support it

4. animation-composition

Controls how multiple animations that target the same properties combine their effects.

.box {
    animation-composition: add;
}

Values

Value	Description
`replace`	New animations overwrite previous ones (default)
`add`	New animations add to existing effects
`accumulate`	Similar to `add`, but with additional rules for keyframes and timing

How It Works

replace (default): The last animation wins.

.box {
    animation-name: moveRight, fadeOut;
    animation-composition: replace;
    /* fadeOut's opacity replaces any opacity from moveRight */
}

add: Effects are combined.

.box {
    animation-name: moveRight, moveUp;
    animation-composition: add;
    /* The box moves both right AND up */
}

accumulate: Similar to add, but keyframe values accumulate.

.box {
    animation-name: scale1, scale2;
    animation-composition: accumulate;
    /* scale1 and scale2 combine their scale values */
}

Key Points:

replace is the default — later animations override earlier ones
add combines transform effects (e.g., translate + rotate)
accumulate is useful for stacking animations with the same property

Complete Example

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Animation Properties — Part 2</title>
    <style>
        *, *::before, *::after {
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            padding: 20px;
            background: #f8f9fa;
            color: #333;
            max-width: 1200px;
            margin: 0 auto;
            line-height: 1.6;
        }

        h1 {
            color: #007bff;
            border-bottom: 3px solid #007bff;
            padding-bottom: 10px;
        }

        h2 {
            color: #28a745;
            border-left: 4px solid #28a745;
            padding-left: 15px;
            margin-top: 30px;
        }

        h3 {
            color: #333;
            margin-top: 20px;
        }

        section {
            background: white;
            padding: 20px;
            border-radius: 8px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            margin: 20px 0;
        }

        .code-block {
            background: #1e1e1e;
            color: #d4d4d4;
            padding: 15px;
            border-radius: 8px;
            overflow-x: auto;
            font-family: 'Courier New', monospace;
            font-size: 0.9rem;
            line-height: 1.8;
            margin: 10px 0;
        }

        .reference-table {
            width: 100%;
            border-collapse: collapse;
            margin: 15px 0;
        }

        .reference-table th,
        .reference-table td {
            padding: 10px;
            border: 1px solid #ddd;
            text-align: left;
        }

        .reference-table th {
            background: #007bff;
            color: white;
        }

        .reference-table tr:nth-child(even) {
            background: #f8f9fa;
        }

        .note {
            font-size: 0.9rem;
            color: #6c757d;
            margin-top: 5px;
        }

        .highlight {
            background: #ffc107;
            color: #333;
            padding: 2px 6px;
            border-radius: 4px;
            font-weight: bold;
        }

        /* ====== DEMO AREA ====== */
        .demo-area {
            display: flex;
            flex-wrap: wrap;
            gap: 40px;
            justify-content: center;
            align-items: center;
            padding: 40px 20px;
            background: #e9ecef;
            border-radius: 8px;
            margin: 15px 0;
            min-height: 200px;
            overflow: hidden;
        }

        /* ====== BASIC ANIMATION ====== */
        .box {
            width: 100px;
            height: 100px;
            background: #007bff;
            border-radius: 12px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
            animation-name: exampleAnimation;
            animation-duration: 2s;
            animation-fill-mode: forwards;
        }

        @keyframes exampleAnimation {
            from {
                transform: translateX(0);
                background-color: #007bff;
            }
            to {
                transform: translateX(200px);
                background-color: #dc3545;
            }
        }

        /* ====== FILL MODE COMPARISON ====== */
        .fill-box {
            width: 80px;
            height: 80px;
            background: #007bff;
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-weight: bold;
            font-size: 0.7rem;
            animation-name: fillDemo;
            animation-duration: 1s;
            animation-delay: 0.5s;
            animation-timing-function: ease;
        }

        .fill-none {
            animation-fill-mode: none;
        }

        .fill-forwards {
            animation-fill-mode: forwards;
        }

        .fill-backwards {
            animation-fill-mode: backwards;
        }

        .fill-both {
            animation-fill-mode: both;
        }

        @keyframes fillDemo {
            from {
                opacity: 0;
                transform: translateX(-50px);
                background: #dc3545;
            }
            to {
                opacity: 1;
                transform: translateX(0);
                background: #28a745;
            }
        }

        /* ====== PLAY STATE ====== */
        .play-container {
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 15px;
        }

        .play-box {
            width: 100px;
            height: 100px;
            background: #6c5ce7;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-weight: bold;
            animation: pulseAnim 1.5s ease-in-out infinite;
        }

        .play-box:hover {
            animation-play-state: paused;
        }

        @keyframes pulseAnim {
            0%, 100% {
                transform: scale(1);
                box-shadow: 0 0 0 0 rgba(108, 92, 231, 0.7);
            }
            50% {
                transform: scale(1.15);
                box-shadow: 0 0 0 15px rgba(108, 92, 231, 0);
            }
        }

        /* ====== COMPOSITION ====== */
        .composition-box {
            width: 80px;
            height: 80px;
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-weight: bold;
            font-size: 0.6rem;
            animation-duration: 3s;
            animation-iteration-count: infinite;
            animation-timing-function: ease-in-out;
        }

        .comp-replace {
            background: #007bff;
            animation-name: moveRight, rotateBox;
            animation-composition: replace;
        }

        .comp-add {
            background: #28a745;
            animation-name: moveRight, moveUp;
            animation-composition: add;
        }

        .comp-accumulate {
            background: #ffc107;
            color: #333;
            animation-name: scaleUp, scaleDown;
            animation-composition: accumulate;
        }

        @keyframes moveRight {
            from { transform: translateX(0); }
            to   { transform: translateX(100px); }
        }

        @keyframes moveUp {
            from { transform: translateY(0); }
            to   { transform: translateY(-50px); }
        }

        @keyframes rotateBox {
            from { transform: rotate(0deg); }
            to   { transform: rotate(180deg); }
        }

        @keyframes scaleUp {
            from { transform: scale(1); }
            to   { transform: scale(1.5); }
        }

        @keyframes scaleDown {
            from { transform: scale(1); }
            to   { transform: scale(0.7); }
        }

        /* ====== SCROLL TIMELINE ====== */
        .scroll-container {
            height: 300px;
            overflow-y: scroll;
            background: #f8f9fa;
            border: 2px solid #ddd;
            border-radius: 8px;
            margin: 15px 0;
            position: relative;
        }

        .scroll-content {
            height: 1200px;
            padding: 20px;
        }

        .scroll-animated-box {
            width: 80px;
            height: 80px;
            background: linear-gradient(135deg, #007bff, #6c5ce7);
            border-radius: 12px;
            position: sticky;
            top: 20px;
            animation-name: scrollAnimation;
            animation-duration: 1s;
            animation-timeline: scroll(nearest);
            animation-fill-mode: both;
        }

        @keyframes scrollAnimation {
            from {
                transform: scale(0.5) rotate(0deg);
                background: #007bff;
                opacity: 0.5;
            }
            to {
                transform: scale(1) rotate(360deg);
                background: #28a745;
                opacity: 1;
            }
        }

        .scroll-instruction {
            position: sticky;
            top: 0;
            background: rgba(255, 255, 255, 0.9);
            padding: 10px;
            border-radius: 8px;
            text-align: center;
            font-weight: bold;
            color: #007bff;
            z-index: 10;
        }

        /* ====== PRACTICAL: HOVER-PAUSE CARD ====== */
        .hover-pause-container {
            display: flex;
            gap: 30px;
            justify-content: center;
            flex-wrap: wrap;
            margin: 20px 0;
        }

        .hover-pause-card {
            width: 180px;
            height: 180px;
            background: linear-gradient(135deg, #007bff, #6c5ce7);
            border-radius: 16px;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            color: white;
            text-align: center;
            padding: 20px;
            cursor: pointer;
            animation: floatCard 3s ease-in-out infinite;
            box-shadow: 0 8px 25px rgba(0, 123, 255, 0.2);
        }

        .hover-pause-card:hover {
            animation-play-state: paused;
        }

        .hover-pause-card .icon {
            font-size: 2.5rem;
            margin-bottom: 10px;
        }

        .hover-pause-card h4 {
            margin: 0;
            font-size: 1rem;
        }

        .hover-pause-card p {
            margin: 5px 0 0 0;
            font-size: 0.8rem;
            opacity: 0.9;
        }

        @keyframes floatCard {
            0%, 100% { transform: translateY(0); }
            50%      { transform: translateY(-15px); }
        }

        /* ====== PRACTICAL: SCROLL PROGRESS ====== */
        .progress-scroll-container {
            height: 250px;
            overflow-y: scroll;
            background: #f8f9fa;
            border: 2px solid #ddd;
            border-radius: 8px;
            margin: 15px 0;
            position: relative;
        }

        .progress-scroll-content {
            height: 1000px;
            padding: 20px;
        }

        .progress-indicator {
            position: sticky;
            top: 0;
            height: 8px;
            background: #e9ecef;
            border-radius: 4px;
            z-index: 10;
        }

        .progress-fill {
            height: 100%;
            background: linear-gradient(90deg, #007bff, #6c5ce7);
            border-radius: 4px;
            animation-name: progressGrow;
            animation-duration: 1s;
            animation-timeline: scroll(nearest);
            animation-fill-mode: both;
            transform-origin: left;
        }

        @keyframes progressGrow {
            from { transform: scaleX(0); }
            to   { transform: scaleX(1); }
        }

        /* ====== TIPS ====== */
        .tip-box {
            padding: 15px;
            border-radius: 8px;
            margin: 10px 0;
            border-left: 4px solid #007bff;
            background: #f8f9fa;
        }

        .tip-box.success { border-left-color: #28a745; }
        .tip-box.warning { border-left-color: #ffc107; }
        .tip-box.danger { border-left-color: #dc3545; }
    </style>
</head>
<body>

    <h1>Animation Properties — Part 2</h1>

    <!-- ====== 1. BASIC ANIMATION WITH FILL-MODE ====== -->
    <section>
        <h2>1. animation-fill-mode: forwards</h2>
        <p>The box stays at its final position and color after the animation ends.</p>

        <div class="demo-area">
            <div class="box"></div>
        </div>

        <div class="code-block">
            .box {
                animation-name: exampleAnimation;
                animation-duration: 2s;
                animation-fill-mode: forwards;
            }

            @keyframes exampleAnimation {
                from { transform: translateX(0); background-color: blue; }
                to   { transform: translateX(200px); background-color: red; }
            }
        </div>

        <p class="note">Without <code>fill-mode: forwards</code>, the box would snap back to its original position and color.</p>
    </section>

    <!-- ====== 2. FILL MODE COMPARISON ====== -->
    <section>
        <h2>2. animation-fill-mode Comparison</h2>
        <p>Refresh the page to see the four fill-mode values in action.</p>

        <div class="demo-area" style="flex-direction: column; gap: 20px; align-items: flex-start;">
            <div style="display: flex; align-items: center; gap: 20px;">
                <span style="font-weight: bold; min-width: 150px;">none:</span>
                <div class="fill-box fill-none">none</div>
            </div>
            <div style="display: flex; align-items: center; gap: 20px;">
                <span style="font-weight: bold; min-width: 150px;">forwards:</span>
                <div class="fill-box fill-forwards">forwards</div>
            </div>
            <div style="display: flex; align-items: center; gap: 20px;">
                <span style="font-weight: bold; min-width: 150px;">backwards:</span>
                <div class="fill-box fill-backwards">backwards</div>
            </div>
            <div style="display: flex; align-items: center; gap: 20px;">
                <span style="font-weight: bold; min-width: 150px;">both:</span>
                <div class="fill-box fill-both">both</div>
            </div>
        </div>

        <div class="code-block">
            .fill-none      { animation-fill-mode: none; }
            .fill-forwards  { animation-fill-mode: forwards; }
            .fill-backwards { animation-fill-mode: backwards; }
            .fill-both      { animation-fill-mode: both; }

            @keyframes fillDemo {
                from { opacity: 0; transform: translateX(-50px); background: #dc3545; }
                to   { opacity: 1; transform: translateX(0); background: #28a745; }
            }
        </div>

        <p class="note"><strong>none</strong> reverts after the animation. <strong>forwards</strong> keeps the end state. <strong>backwards</strong> applies the start state during the delay. <strong>both</strong> does both.</p>
    </section>

    <!-- ====== 3. ANIMATION-PLAY-STATE ====== -->
    <section>
        <h2>3. animation-play-state</h2>
        <p>Hover over the box to pause the animation.</p>

        <div class="demo-area">
            <div class="play-container">
                <div class="play-box">Hover to Pause</div>
            </div>
        </div>

        <div class="code-block">
            .play-box {
                animation: pulseAnim 1.5s ease-in-out infinite;
            }

            .play-box:hover {
                animation-play-state: paused;
            }
        </div>
    </section>

    <!-- ====== 4. ANIMATION-COMPOSITION ====== -->
    <section>
        <h2>4. animation-composition</h2>
        <p>Compare how multiple animations combine with different composition values.</p>

        <div class="demo-area" style="flex-direction: column; gap: 25px; align-items: flex-start;">
            <div style="display: flex; align-items: center; gap: 20px;">
                <span style="font-weight: bold; min-width: 180px;">replace (default):</span>
                <div class="composition-box comp-replace">replace</div>
            </div>
            <div style="display: flex; align-items: center; gap: 20px;">
                <span style="font-weight: bold; min-width: 180px;">add:</span>
                <div class="composition-box comp-add">add</div>
            </div>
            <div style="display: flex; align-items: center; gap: 20px;">
                <span style="font-weight: bold; min-width: 180px;">accumulate:</span>
                <div class="composition-box comp-accumulate">accumulate</div>
            </div>
        </div>

        <div class="code-block">
            /* replace: later animation overwrites earlier */
            .comp-replace {
                animation-name: moveRight, rotateBox;
                animation-composition: replace;
            }

            /* add: effects combine (move right AND up) */
            .comp-add {
                animation-name: moveRight, moveUp;
                animation-composition: add;
            }

            /* accumulate: scale values add together */
            .comp-accumulate {
                animation-name: scaleUp, scaleDown;
                animation-composition: accumulate;
            }
        </div>

        <p class="note">With <code>add</code>, the box moves both right and up. With <code>replace</code>, only the second animation's transform applies.</p>
    </section>

    <!-- ====== 5. ANIMATION-TIMELINE (SCROLL) ====== -->
    <section>
        <h2>5. animation-timeline: scroll()</h2>
        <p>Scroll inside the box to see the animation progress with the scroll position.</p>

        <div class="scroll-container">
            <div class="scroll-content">
                <div class="scroll-instruction">⬇️ Scroll down to animate ⬇️</div>
                <div class="scroll-animated-box"></div>
                <p style="margin-top: 20px; color: #6c757d;">
                    The box grows, rotates, and changes color as you scroll.
                    Keep scrolling to see the full animation.
                </p>
                <p style="margin-top: 200px; color: #6c757d;">
                    The animation is driven by the scroll position — not by time.
                </p>
                <p style="margin-top: 200px; color: #6c757d;">
                    Near the bottom — the animation is almost complete.
                </p>
                <p style="margin-top: 200px; color: #6c757d;">
                    🎉 You've reached the end!
                </p>
            </div>
        </div>

        <div class="code-block">
            .scroll-animated-box {
                animation-name: scrollAnimation;
                animation-duration: 1s;
                animation-timeline: scroll(nearest);
                animation-fill-mode: both;
            }

            @keyframes scrollAnimation {
                from {
                    transform: scale(0.5) rotate(0deg);
                    background: #007bff;
                    opacity: 0.5;
                }
                to {
                    transform: scale(1) rotate(360deg);
                    background: #28a745;
                    opacity: 1;
                }
            }
        </div>

        <div class="tip-box warning">
            <strong>⚠️ Browser Support:</strong>
            <code>animation-timeline</code> is a modern feature. Check <a href="https://caniuse.com/css-scroll-timeline" target="_blank">caniuse.com</a> for current browser support.
        </div>
    </section>

    <!-- ====== 6. PRACTICAL: HOVER-PAUSE CARDS ====== -->
    <section>
        <h2>6. Practical Example: Hover-Pause Cards</h2>
        <p>Hover over a card to pause its floating animation.</p>

        <div class="hover-pause-container">
            <div class="hover-pause-card">
                <div class="icon">🚀</div>
                <h4>Fast</h4>
                <p>Hover to pause</p>
            </div>
            <div class="hover-pause-card">
                <div class="icon">🎨</div>
                <h4>Beautiful</h4>
                <p>Hover to pause</p>
            </div>
            <div class="hover-pause-card">
                <div class="icon">🔒</div>
                <h4>Secure</h4>
                <p>Hover to pause</p>
            </div>
        </div>

        <div class="code-block">
            .hover-pause-card {
                animation: floatCard 3s ease-in-out infinite;
            }

            .hover-pause-card:hover {
                animation-play-state: paused;
            }

            @keyframes floatCard {
                0%, 100% { transform: translateY(0); }
                50%      { transform: translateY(-15px); }
            }
        </div>
    </section>

    <!-- ====== 7. PRACTICAL: SCROLL PROGRESS ====== -->
    <section>
        <h2>7. Practical Example: Scroll Progress Bar</h2>
        <p>Scroll inside the box to see the progress bar fill based on scroll position.</p>

        <div class="progress-scroll-container">
            <div class="progress-scroll-content">
                <div class="progress-indicator">
                    <div class="progress-fill"></div>
                </div>
                <p style="margin-top: 20px; color: #6c757d;">
                    The progress bar at the top fills as you scroll.
                </p>
                <p style="margin-top: 300px; color: #6c757d;">
                    Keep scrolling to see the progress grow.
                </p>
                <p style="margin-top: 300px; color: #6c757d;">
                    Almost there...
                </p>
                <p style="margin-top: 300px; color: #6c757d;">
                    🎉 Complete!
                </p>
            </div>
        </div>

        <div class="code-block">
            .progress-fill {
                animation-name: progressGrow;
                animation-duration: 1s;
                animation-timeline: scroll(nearest);
                animation-fill-mode: both;
                transform-origin: left;
            }

            @keyframes progressGrow {
                from { transform: scaleX(0); }
                to   { transform: scaleX(1); }
            }
        </div>
    </section>

    <!-- ====== 8. REFERENCE TABLES ====== -->
    <section>
        <h2>8. Reference Tables</h2>

        <h3>Animation Properties — Part 2</h3>
        <table class="reference-table">
            <tr>
                <th>Property</th>
                <th>Description</th>
                <th>Default</th>
            </tr>
            <tr>
                <td><code>animation-fill-mode</code></td>
                <td>Styles before/after animation</td>
                <td><code>none</code></td>
            </tr>
            <tr>
                <td><code>animation-play-state</code></td>
                <td>Running or paused</td>
                <td><code>running</code></td>
            </tr>
            <tr>
                <td><code>animation-timeline</code></td>
                <td>Timeline that controls the animation</td>
                <td><code>auto</code></td>
            </tr>
            <tr>
                <td><code>animation-composition</code></td>
                <td>How multiple animations combine</td>
                <td><code>replace</code></td>
            </tr>
        </table>

        <h3>animation-fill-mode Values</h3>
        <table class="reference-table">
            <tr>
                <th>Value</th>
                <th>Description</th>
            </tr>
            <tr>
                <td><code>none</code></td>
                <td>No styles applied outside the animation (default)</td>
            </tr>
            <tr>
                <td><code>forwards</code></td>
                <td>Keep the last keyframe's styles</td>
            </tr>
            <tr>
                <td><code>backwards</code></td>
                <td>Apply the first keyframe's styles during delay</td>
            </tr>
            <tr>
                <td><code>both</code></td>
                <td>Apply both forwards and backwards</td>
            </tr>
        </table>

        <h3>animation-play-state Values</h3>
        <table class="reference-table">
            <tr>
                <th>Value</th>
                <th>Description</th>
            </tr>
            <tr>
                <td><code>running</code></td>
                <td>Animation is playing (default)</td>
            </tr>
            <tr>
                <td><code>paused</code></td>
                <td>Animation is paused</td>
            </tr>
        </table>

        <h3>animation-timeline Values</h3>
        <table class="reference-table">
            <tr>
                <th>Value</th>
                <th>Description</th>
            </tr>
            <tr>
                <td><code>auto</code></td>
                <td>Default document timeline (default)</td>
            </tr>
            <tr>
                <td><code>none</code></td>
                <td>No timeline — animation doesn't play</td>
            </tr>
            <tr>
                <td><code>scroll()</code></td>
                <td>Binds animation to scroll position</td>
            </tr>
            <tr>
                <td><code>view()</code></td>
                <td>Binds animation to element visibility in viewport</td>
            </tr>
        </table>

        <h3>animation-composition Values</h3>
        <table class="reference-table">
            <tr>
                <th>Value</th>
                <th>Description</th>
            </tr>
            <tr>
                <td><code>replace</code></td>
                <td>New animations overwrite previous ones (default)</td>
            </tr>
            <tr>
                <td><code>add</code></td>
                <td>New animations add to existing effects</td>
            </tr>
            <tr>
                <td><code>accumulate</code></td>
                <td>Similar to add, with additional rules for keyframes</td>
            </tr>
        </table>
    </section>

    <!-- ====== 9. BEST PRACTICES ====== -->
    <section>
        <h2>9. Best Practices</h2>

        <div style="background: #d4edda; padding: 20px; border-radius: 8px; border-left: 4px solid #28a745;">
            <h3 style="margin-top: 0; color: #155724;">✅ Do This:</h3>
            <ul>
                <li>Use <code>animation-fill-mode: forwards</code> to keep the end state</li>
                <li>Use <code>animation-fill-mode: backwards</code> to apply start styles during delay</li>
                <li>Use <code>animation-play-state: paused</code> on hover for interactive control</li>
                <li>Use <code>animation-timeline: scroll()</code> for scroll-driven animations</li>
                <li>Use <code>animation-composition: add</code> to combine transform effects</li>
                <li>Always provide fallbacks for modern features</li>
                <li>Respect <code>prefers-reduced-motion</code> for accessibility</li>
            </ul>
        </div>

        <div style="background: #f8d7da; padding: 20px; border-radius: 8px; border-left: 4px solid #dc3545; margin-top: 15px;">
            <h3 style="margin-top: 0; color: #721c24;">❌ Don't Do This:</h3>
            <ul>
                <li>Don't forget <code>animation-fill-mode</code> — elements snap back without it</li>
                <li>Don't use <code>animation-timeline</code> without a fallback for unsupported browsers</li>
                <li>Don't confuse <code>animation-composition: add</code> with <code>replace</code></li>
                <li>Don't pause animations that are essential for feedback</li>
                <li>Don't forget that scroll-driven animations need a scrollable container</li>
                <li>Don't forget about <code>prefers-reduced-motion</code></li>
            </ul>
        </div>

        <div class="code-block">
            /* Accessibility: respect reduced motion */
            @media (prefers-reduced-motion: reduce) {
                .box,
                .fill-box,
                .play-box,
                .composition-box,
                .scroll-animated-box,
                .hover-pause-card {
                    animation: none;
                }
            }

            /* Scroll-driven animation with fallback */
            .scroll-animated-box {
                animation-name: scrollAnimation;
                animation-duration: 1s;
                animation-fill-mode: both;
            }

            @supports (animation-timeline: scroll()) {
                .scroll-animated-box {
                    animation-timeline: scroll(nearest);
                }
            }
        </div>
    </section>

</body>
</html>

Quick Reference

Property	Description	Default
`animation-fill-mode`	Styles before/after animation	`none`
`animation-play-state`	Running or paused	`running`
`animation-timeline`	Timeline that controls the animation	`auto`
`animation-composition`	How multiple animations combine	`replace`

animation-fill-mode Values

Value	Description
`none`	No styles applied outside the animation (default)
`forwards`	Keep the last keyframe’s styles
`backwards`	Apply the first keyframe’s styles during delay
`both`	Apply both forwards and backwards

animation-play-state Values

Value	Description
`running`	Animation is playing (default)
`paused`	Animation is paused

animation-timeline Values

Value	Description
`auto`	Default document timeline (default)
`none`	No timeline — animation doesn’t play
`scroll()`	Binds animation to scroll position
`view()`	Binds animation to element visibility

animation-composition Values

Value	Description
`replace`	New animations overwrite previous ones (default)
`add`	New animations add to existing effects
`accumulate`	Similar to add, with additional rules for keyframes

Best Practices

✅ Do This:

/* Keep the end state */
.box {
    animation-fill-mode: forwards;
}

/* Pause on hover */
.box:hover {
    animation-play-state: paused;
}

/* Scroll-driven animation with fallback */
@supports (animation-timeline: scroll()) {
    .box {
        animation-timeline: scroll();
    }
}

/* Combine transforms */
.box {
    animation-name: moveRight, rotate;
    animation-composition: add;
}

/* Respect reduced motion */
@media (prefers-reduced-motion: reduce) {
    .box {
        animation: none;
    }
}

❌ Don’t Do This:

/* Don't forget fill-mode */
.box {
    animation: slideIn 1s;
    /* Snaps back after animation */
}

/* Don't use animation-timeline without fallback */
.box {
    animation-timeline: scroll();
    /* Won't work in unsupported browsers */
}

/* Don't use replace when you want combined effects */
.box {
    animation-name: moveRight, moveUp;
    animation-composition: replace;
    /* Only moveUp applies — moveRight is overwritten */
}

Pro Tip: animation-fill-mode: forwards is essential for entrance animations — without it, elements snap back to their original state. animation-play-state: paused on hover gives users control over animations, which is great for accessibility. animation-timeline: scroll() enables scroll-driven animations — a modern, performant way to create engaging scroll experiences (always provide a fallback). animation-composition: add lets you combine multiple transforms (e.g., move right AND rotate). And always respect prefers-reduced-motion — some users experience discomfort from animations!

Stop using slow, ad-bloated tool sites! 🤮

🔎 Search “KandZ Tools” on Google to use many professional utilities for free.

KandZ.me is the ultimate minimalist hub for:
✅ Finance (Mortgage, Interest, Inflation)
✅ Tech (Base64, JSON, Dev Suite, IP)
✅ Health (BMI, BMR, TDEE)
✅ Productivity (Timer, Workspace, QR)

⚡️ Fast & Private
🔒 No data leaves your device
💎 100% Free

🔗 Use it now: https://tools.kandz.me
🔖 Bookmark it—you’ll need it later!

Overview of Properties

1. animation-fill-mode

Values

Visual Explanation

2. animation-play-state

Values

3. animation-timeline

Values

scroll() Timeline

view() Timeline

4. animation-composition

Values

How It Works

Complete Example

Quick Reference

animation-fill-mode Values

animation-play-state Values

animation-timeline Values

animation-composition Values

Best Practices

Ads Blocker Detected!!!