index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Letter Paper</title>
    <script src="libs/vue.min.js"></script>
    <link href="https://fonts.googleapis.com/css2?family=Spartan&display=swap" rel="stylesheet">
    <link rel="stylesheet" href="libs/normalize.css">
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <div id="app">
        <div class="row" v-for="(item, index) in lines" :key="index">
            <div class="line l1"></div>
            <div class="line l2"></div>
            <div class="line l3"></div>
            <div class="line l4"></div>
            
            <input type="text">
        </div>
        <div class="action" @click="addRow()">新增一行</div>
    </div>
    <script src="script.js"></script>
</body>
</html>