在IE11中不垂直居中的文本(特殊unicode，如⇑)

<style>
    .container {
        display: flex;
        align-items: center;
        height: 100vh;
    }
</style>

<div class="container">
    <span>&#8657;</span>
</div>

<style>
    .container {
        display: table;
        height: 100vh;
    }

    .cell {
        display: table-cell;
        vertical-align: middle;
    }
</style>

<div class="container">
    <div class="cell">
        <span>&#8657;</span>
    </div>
</div>

<style>
    .container {
        position: relative;
        height: 100vh;
    }

    .child {
        position: absolute;
        top: 50%;
        transform: translateY(-50%);
    }
</style>

<div class="container">
    <span class="child">&#8657;</span>
</div>