| 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364 | <!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <meta name="viewport" content="width=device-width, initial-scale=1.0">    <title>Document</title>    <style>        .box{            width: 100px;            height: 100px;            background-color: red;            animation-name: foo;            animation-duration: 1s;            animation-timing-function: linear;            /* animation-iteration-count: 2; */            animation-fill-mode: forwards;        }        @keyframes foo {            0%{                width: 100px;                height: 100px;            }            50%{                width: 300px;                height: 100px;            }            100%{                width: 300px;                height: 300px;            }        }                /* .div1{            width: 0;            height: 0;            margin:100px auto;            border-top: 50px solid red;            border-left: 50px solid blue;            border-right: 50px solid yellow;            border-bottom: 50px solid green;            animation-name: foo;            animation-duration: 1s;            animation-timing-function: linear;            animation-iteration-count: infinite;            animation-delay: 2s;        } */        /* @keyframes foo {            from{                transform: rotate(0);            }            to{                transform: rotate(360deg);            }        } */        .div1:hover{            animation-play-state: paused;        }    </style></head><body>    <div class="box"></div>    <!-- <div class="div1"></div> --></body></html>
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