<script>
let big = false;
let color = "green"
</script>
<label>
<input type="checkbox" bind:checked={big} />
big
</label>
<p class:big style:color>
My dynamic color is {color} and I am a {big ? 'big' : 'small'} text
</p>
<style>
.big {
font-size: 4em;
}
</style>