关键js代码

   <script>
        function countdown() {
            var targetDate = new Date("2024-02-20 12:00:00");
            var currentDate = new Date();
            var timeDiff = targetDate.getTime() - currentDate.getTime();
            var days = Math.floor(timeDiff / (1000 * 60 * 60 * 24));
            var hours = Math.floor((timeDiff % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
            var minutes = Math.floor((timeDiff % (1000 * 60 * 60)) / (1000 * 60));
            var seconds = Math.floor((timeDiff % (1000 * 60)) / 1000);
            let time = `距离2024-01-15 12:00:00还有：${days}天${ hours}时${minutes}分${seconds}秒 `;
            document.querySelector('#div').innerHTML = time;
        }
        countdown()
        setInterval(function () {
            countdown()
        }, 1000);
    </script>

美化css代码

    <style>
        #div {
            width: 800px;
            height: 100px;
            margin: 200px auto;
            background-color: black;
            color: #fff;
            font-size: 30px;
            text-align: center;
            line-height: 100px;
            border-radius: 20px;
        }
    </style>

运行效果：