2021年的读者:

试试这个:

.parent {
  position: relative;

  display: flex;                 // And you will probably need this too.
  flex-direction: row;           // or column.
}

.child {
  position: absolute;
  top: 0;
  bottom: 0;

  align-self: center;            // And you will probably need this too.
}

以下是我正在做的事情:

你可以把display: flex到div#主，align-self: stretch到div#导航。

<div id="header"></div>

<div id="main">
  <div id="navigation"></div>
  <div id="content"></div>
</div>

<div id="footer"></div>

// CSS file
#main {
  display: flex;
}

#navigation {
  align-self: stretch;
}    

这道题的题目和内容有点矛盾。标题说的是父div，但问题让它听起来像你想要两个兄弟div(导航和内容)是相同的高度。

你(a)希望导航和内容都是主高度的100%，还是(b)希望导航和内容是相同的高度?

我假设(b)……如果是这样的话，我不认为你将能够做到这一点，因为你目前的页面结构(至少，不是纯CSS和没有脚本)。你可能需要这样做:

<main div>
    <content div>
         <navigation div></div>
    </div>
</div>

并将内容div设置为左侧空白，无论导航窗格的宽度是多少。这样，内容的内容就在导航栏的右边，你可以将导航栏的高度设置为内容高度的100%。

编辑:我完全是在我的头脑中做的，但你可能还需要将导航div的左侧空白设置为负值，或将它的绝对左侧设置为0，以将它推回到最左边。问题是，有很多方法可以实现这一点，但并不是所有的方法都能与所有浏览器兼容。

下面的代码提供了设置滚动div的最小高度的能力，并通过使用flex使其具有其父div的100%高度。

CSS:

.main {
  display: flex;
  flex-direction: column;
}

.scroll {
  overflow: auto;
  flex: 1 0 50px;
}

HTML:

<div class="main">
  <div class="scroll">
    Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
  </div>
</div>

#main {
   display: table;
} 
#navigation, #content {
   display: table-cell;
}

看看这个例子。

我有同样的问题，它的工作基于Hakam Fostok的答案，我已经创建了一个小例子，在某些情况下，它可能不需要添加显示:flex;而弯曲方向:圆柱;在父容器上

.row {
    margin-top: 20px;
}

.col {
    box-sizing: border-box;
    border: solid 1px #6c757d;
    padding: 10px;
}

.card {
    background-color: #a0a0a0;
    height: 100%;
}

JSFiddle