HTMLDocument.style detail

HTMLDocument.style is point to DOM

<style>
.d{
	color: red;
}
</style>
<div class="d">DOM</div>
<script>
console.log(document.querySelector('.d').style.color)
// 空
</script>

<style>
.d{
	color: red;
}
</style>
<div class="d" style="color: green;">DOM</div>
<script>
console.log(document.querySelector('.d').style.color)
// green
</script>

So it mean HTMLDocument.style just refer html label. Even though you have written the color in css file but not written in html label, it just print ‘’ in terminal.