Attach a class

App.xht

<script>
    import Button from './Button.xht';
</script>

<h1>Pass class</h1>

<Button name="Red" class="btn" />
<Button name="Default" />

<style>
    .btn {color: red;}
    h1 {color: brown;}
</style>

Button.xht

<script>
    export let name;
</script>

<button class="btn">{name}</button>

<style>
    .btn {font-style: italic;}
    :export(.btn) {color: deepskyblue;}
</style>