margin和text-align以及align

margin和text-align是css样式，align是html的

<style>
    .test {
        width: 400px;
        height: 200px;
        background: green;
    }

    .rectangle {
        width: 200px;
        height: 100px;
        background: blue;
    }

    .test-center1 {
        margin: 0 auto;
    }

    .test-center3 {
        text-align: center;
    }
</style>

<div class="test">
    <div class="rectangle test-center1">
        test1
    </div>
</div>
<br />
<div class="test">
    <div class="rectangle" align="center">
        test2
    </div>
</div>
<br />
<div class="test">
    <div class="rectangle test-center3">
        test3
    </div>
</div>