Css 如何保持内容垂直居中，并使用滚动条显示任何垂直溢出？

我有一个内容区域，其行为应如下所示：

• 如果没有垂直溢出，内容将垂直居中（当前通过

  显示：table/-cell

  ）
• 除非存在垂直溢出，否则不会显示滚动条
• 包含div的高度永远不会更改

我只能满足第一点-小提琴：

<div class="row-fluid card-box">

    <div class="span4 side-study-box">
        <div class="side-box-content">
            <pre class="text-content-saved">TEST 
           TEST</pre>
            </div>
        </div>
</div>

.side-study-box {
    background-color: white;
    color: black;
    border: 1px solid #3D6AA2;
    text-align: center;
    height: 160px !important;
    max-height: 160px !important;
    display: table !important;
    margin: 0px !important;
    margin-left: -1px !important;
    position: relative;
    overflow-y: scroll !important;
}

    .side-study-box .side-box-content {
        width: calc(100%);
        height: 160px !important;
        float: right;
        display: table;
        overflow-y: scroll !important;
        background-color: white;
    }

    /*#region CONTENT AREAS */

    /*#region TEXT CONTENT */
    .side-study-box .text-content-saved {
        width: calc(100%+29px) !important;
        font-size: 24px;
        display: table-cell;
        vertical-align: middle;
        text-align: center;
        height: 160px !important;
        max-height: 160px !important;
        background-color: white;
        padding: 0px !important;
        margin: 0px !important;
        border: 0px !important;
        overflow-y: scroll !important;
    }

这是我的html:

<div class="row-fluid card-box">

    <div class="span4 side-study-box">
        <div class="side-box-content">
            <pre class="text-content-saved">TEST 
           TEST</pre>
            </div>
        </div>
</div>

.side-study-box {
    background-color: white;
    color: black;
    border: 1px solid #3D6AA2;
    text-align: center;
    height: 160px !important;
    max-height: 160px !important;
    display: table !important;
    margin: 0px !important;
    margin-left: -1px !important;
    position: relative;
    overflow-y: scroll !important;
}

    .side-study-box .side-box-content {
        width: calc(100%);
        height: 160px !important;
        float: right;
        display: table;
        overflow-y: scroll !important;
        background-color: white;
    }

    /*#region CONTENT AREAS */

    /*#region TEXT CONTENT */
    .side-study-box .text-content-saved {
        width: calc(100%+29px) !important;
        font-size: 24px;
        display: table-cell;
        vertical-align: middle;
        text-align: center;
        height: 160px !important;
        max-height: 160px !important;
        background-color: white;
        padding: 0px !important;
        margin: 0px !important;
        border: 0px !important;
        overflow-y: scroll !important;
    }

---

这可以通过使用一些基本的CSS和一点jQuery来实现

看看我的小提琴。请随意填充内容，使其更大，并查看ti的反应

HTML

<div id="holder">
    <div id="text">
        test<br/>
        test<br/>
        test<br/>
        test
    </div>    
</div>

JQuery

var holder = $('#holder');
var text = $('#text');

if (text.height()<holder.height()){
    var y=(holder.height()/2) - (text.height()/2);
    text.css({top:y+'px'});
}

var holder=$（“#holder”）；
var text=$（“#text”）；
if（text.height（）