Vue Js concat string and variable

<html>
<head>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
    <div id="app">
        <h3>Vue Js concat string and varibale</h3>
        <p>{{ message }}</p>
        <p>{{ concatenatedString }}</p>
    </div>

/* CSS for the heading */
        h3 {
            font-size: 24px;
            color: #333;
            margin-bottom: 10px;
        }

/* CSS for the paragraphs */
        p {
            font-size: 18px;
            color: #555;
            margin-bottom: 5px;
        }

/* CSS for the interpolated message */
        p:first-child {
            color: #ff5722;
        }

/* CSS for the concatenated string */
        p:last-child {
            font-weight: bold;
        }
    </style>
</body>

</html>