为什么我的 CSS3 旋转动画在 Chrome 中不起作用？

<p>To use CSS3 Animation you must also define the actual animation keyframes (<em>which you named spin</em>)</p>
<p>Read https://developer.mozilla.org/en-US/docs/CSS/Tutorials/Using_CSS_animations for more info</p>
<blockquote>
<p>Once you've configured the animation's timing, you need to define the appearance of the animation. This is done by establishing two or more keyframes using the @keyframes at-rule. Each keyframe describes how the animated element should render at a given time during the animation sequence.</p>
</blockquote>

<div class="snippet" data-lang="js" data-hide="true" data-console="true" data-babel="false">
<div class="snippet-code snippet-currently-hidden">
<pre class="snippet-code-css lang-css prettyprint-override">div {
    margin: 20px;
    width: 100px;
    height: 100px;
    background: #f00;
    -webkit-animation-name: spin;
    -webkit-animation-duration: 4000ms;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-timing-function: linear;
    -moz-animation-name: spin;
    -moz-animation-duration: 4000ms;
    -moz-animation-iteration-count: infinite;
    -moz-animation-timing-function: linear;
    -ms-animation-name: spin;
    -ms-animation-duration: 4000ms;
    -ms-animation-iteration-count: infinite;
    -ms-animation-timing-function: linear;
    
    animation-name: spin;
    animation-duration: 4000ms;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
}
@-ms-keyframes spin {
    from { -ms-transform: rotate(0deg); }
    to { -ms-transform: rotate(360deg); }
}
@-moz-keyframes spin {
    from { -moz-transform: rotate(0deg); }
    to { -moz-transform: rotate(360deg); }
}
@-webkit-keyframes spin {
    from { -webkit-transform: rotate(0deg); }
    to { -webkit-transform: rotate(360deg); }
}
@keyframes spin {
    from {
        transform:rotate(0deg);
    }
    to {
        transform:rotate(360deg);
    }
}

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