/*等同如下*/transition-property: width;transition-duration: 1s;transition-timing-function: linear;transition-delay: 2s;

/*css代碼*/h2{    position: relative;    padding: 15px;    text-align: center;    }button{    width: 100px;    height: 40px;    border-radius: 15px;    border: none;    background: #188FF7;    color: #fff;    outline: none;    cursor: pointer;    font-weight: bold;}button:hover{    background: #188EA7;}.container{    width: 600px;    display: flex;    flex-direction: column;    align-items: center;    margin: 0 auto;    }.line{    position: absolute;    left: 0;    bottom: 0;    height: 3px;    width: 100%;    transition: transform .5s;    background: #188EA7;    color: #188EA7;    transform: scaleX(0);    z-index: 1111;            }@keyframes changeColor1{    from{        color: #000;    }    to{        color: #188EA7;    }}@keyframes changeColor2{    from{                        color: #188EA7;    }    to{        color: #000;    }}<!--html代碼--><div class="container">    <h2 id="title">        百度前端學院        <i class="line" id="line"></i>    </h2>    <button id="change">Change</button></div>//js部分代碼(function () {    let btn = document.getElementById('change');    let h2 = document.getElementById('title');    let line = document.getElementById('line');    let count = 0;    btn.onclick = function () {        if(count%2===0){            line.style.transform = "scaleX(1)";            h2.style.animation = "changeColor1 1s";            h2.style.color = "#188EA7";            count++;        }else{            line.style.transform = "scaleX(0)";            h2.style.animation = "changeColor2 1s";            h2.style.color = "#000";            count++;        }            }})();