嵌套的flexbox高度与最大高度 [英] nested flexbox height vs max-height
问题描述
更新:我在Chrome 72上看到这种奇怪的行为.FireFox64可以！！
update: I see this strange behavior on Chrome 72. FireFox 64 is OK!
我在嵌套的flexbox上遇到问题.
I have a problem with a nested flexbox.
在下面的代码段中，我为.root.container添加了一个虚拟的XL高度，因此当有很多 个项目溢出可用的最大高度时，结果正是我想要的.
In the snippet below I added a dummy XL height to .root.container, so that the result is exactly what I want when there are many items that overflow the available max-height.
相反，当个项目很少时，.root.container不应扩展到所有可用高度.
Conversely, when there are few items, the .root.container should not extend to all available height.
换句话说，我希望.root.container的高度为auto，但我不知道如何.
删除其虚拟高度后，溢出将在.root.content而不是.sub.content上触发.
In other terms, I want .root.container height to be auto, but I can't figure how.
Removing its dummy height, the overflow is triggered on .root.content instead of .sub.content.
请帮助我了解flexbox在这种特殊情况下如何工作.
Please, help me understand how flexbox works in this particular situation.
P.S.小提琴也可用此处
P.S. fiddle also available here
html, body {
height: 100%;
margin: 0;
padding: 0;
}
* {
box-sizing: border-box;
}
div {
padding: 10px;
}
.container {
display: flex;
flex-direction: column;
}
.content {
flex: 1;
max-height: 100%;
overflow: auto;
}
.root.container {
background-color: red;
max-height: 100%;
height: 999999px; /* i want height to be 'auto' */
}
.sub.container {
background-color: purple;
height: 100%;
}
.root.header {
background-color: lightblue;
}
.sub.header {
background-color: lightgreen;
}
.root.content {
background-color: yellow;
}
.sub.content {
background-color: orange;
}
<div class="root container">
<div class="root header">header</div>
<div class="root content">
<div class="sub container">
<div class="sub header">menu</div>
<div class="sub content">
<ul>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
</ul>
</div>
</div>
</div>
</div>
推荐答案
设置高度时，您的代码按预期工作，因为max-height:100%
Your code is working as expected when setting the big height because max-height:100% in the child element need a reference, if you remove the height the max-height will fail to auto. As a side note, Firefox will have the same output even if you remove max-height so the issue isn't related to max-height. 1
相反，您可以保留级联的flex容器，并依靠默认的拉伸对齐方式来获得所需的内容:
Instead, you can keep the cascading flex container and rely on the default stretch alignment to obtain what you want:
html, body {
height: 100%;
margin: 0;
padding: 0;
}
* {
box-sizing: border-box;
}
div {
padding: 10px;
}
.container {
display: flex;
flex-direction: column;
}
.content {
flex: 1;
max-height: 100%;
overflow: auto;
}
.root.container {
background-color: red;
max-height: 100%;
}
.sub.container {
background-color: purple;
width:100%; /*added this*/
}
.root.header {
background-color: lightblue;
}
.sub.header {
background-color: lightgreen;
}
.root.content {
background-color: yellow;
display:flex; /*added this*/
}
.sub.content {
background-color: orange;
}
<div class="root container">
<div class="root header">header</div>
<div class="root content">
<div class="sub container">
<div class="sub header">menu</div>
<div class="sub content">
<ul>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
</ul>
</div>
</div>
</div>
</div>
为更好地了解此问题，让我们删除一些属性，并仅保留将触发不同行为的所需属性:
To better see the issue let's remove some properties and keep only the needed ones that will trigger the different behavior:
html, body {
height: 100%;
margin: 0;
padding: 0;
}
* {
box-sizing: border-box;
}
div {
padding: 10px;
}
.container {
display: flex;
flex-direction: column;
}
.content {
flex: 1;
overflow: auto;
}
.root.container {
background-color: red;
max-height: 100%;
}
.sub.container {
background-color: purple;
height: 100%;
}
.root.header {
background-color: lightblue;
}
.sub.header {
background-color: lightgreen;
}
.root.content {
background-color: yellow;
}
.sub.content {
background-color: orange;
}
<div class="root container">
<div class="root header">header</div>
<div class="root content">
<div class="sub container">
<div class="sub header">menu</div>
<div class="sub content">
<ul>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
<li>Item 4</li>
<li>Item 5</li>
</ul>
</div>
</div>
</div>
</div>
所有问题均与.sub.container上使用的内部height:100%有关.从技术上来讲，考虑到规范，该高度应该不能为auto，因为未设置父高度，但是Firefox似乎可以评估该高度.可能是由于嵌套的flex容器，我们可以在知道内容或仅仅是一个bug之前就评估父级的高度.
All the issue is related to the inner height:100% used on the .sub.container. Technically and considering the specification this height should fail to auto because the parent height isn't set BUT Firefox seems to be able to evalute this height. Probably due to the nested flex container where we can evaluate the parent height before knowing the content or simply a bug.
Chrome并没有这样做，只是忽略了逻辑上的高度.
Chrome is not doing this and simply ignoring the height which is the logical behavior.
这篇关于嵌套的flexbox高度与最大高度的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
