<head>
<style>
.app div {
    border: 1px solid black;
    Background-color: red;
}
</style>
</head>
<body>
    <div class="app">
        <div><p>I should have a red background</p></div>
    </div>
    <div class="app">
        <div><p>I should have a red background</p></div>
    </div>
</body>