SOURCE

<div class="container">
	<div class="head">头</div>
	<div class="content">
        <div contenteditable="true">123</div>
    </div>
	<div class="foot">尾巴</div>
</div>

.container {
    border: 1px solid green;
    max-height: 200px;
    width: 100px;
    display: flex;
    flex-direction: column;
}

.content {
    border-top: 1px solid green;
    border-bottom: 1px solid green;
    overflow: auto;
}