How to make Flexbox (flex-grow) take content into

问题:

How can we get Flexbox to stop equalizing space in sibling elements when both of the elements are using flex-grow: 1. This is difficult to explain upfront, so here is the code quickly followed by example screenshots of the issue, and desired behavior.

.Parent {
  display: flex;
  flex-direction: column;
  background-color: lightcoral;
  width: 400px;
  min-height: 200px;
}

.Parent>div {
  flex: 1;
}

.child1 {
  background-color: lightblue;
}

.child2 {
  background-color: lightgreen;
}

<div class="Parent">
  <div class="child1">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam sagittis lorem at odio euismod tincidunt. Proin aliquet velit nec augue venenatis laoreet. Etiam nec metus mi. Aliquam sit amet velit non lectus porttitor accumsan sit amet egestas risus.</div>
  <div class="child2">Lorem ipsum</div>
</div>

The issue:

Notice the equal space under the content of each div.

Desired:

When there is little content in the children divs, the divs should be of equal height:

When one of the divs has a lot of content, I would expect the div with more content to only be as tall as the content (if it passes the original flex grow allotment).

How can I get this behavior? Seems it should be easy using Flexbox.

回答1:

flex-basis is the property you're looking for. https://developer.mozilla.org/en-US/docs/Web/CSS/flex-basis

The flex-basis CSS property specifies the flex basis which is the initial main size of a flex item. This property determines the size of the content-box unless specified otherwise using box-sizing.

By default, flex will take into account the content in the element when computing flex-grow - to disable that, just specify flex-basis: 0

.Parent {
  display: flex;
  flex-direction: column;
  background-color: lightcoral;
  width: 400px;
  min-height: 200px;
}

.Parent>div {
  flex-grow: 1;
  flex-basis: 0;
}

.child1 {
  background-color: lightblue;
}

.child2 {
  background-color: lightgreen;
}

<div class="Parent">
  <div class="child1">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam sagittis lorem at odio euismod tincidunt. Proin aliquet velit nec augue venenatis laoreet. Etiam nec metus mi. Aliquam sit amet velit non lectus porttitor accumsan sit amet egestas risus. Etiam nec metus mi. Aliquam sit amet velit non lectus porttitor accumsan sit amet egestas risus </div>
  <div class="child2">Lorem ipsum</div>
</div>

回答2:

By setting min-height on .Parent (along with setting the flex-direction to column), you're triggering the browser to fill the space with direct descendants of .Parent. It does so by distributing the space amongst all elements equally (that's the feature of Flexbox).

If you don't want that behavior, remove the min-height from .Parent and set a min-height on .Parent > div elements.

.Parent {
  display: flex;
  flex-direction: column;
  background-color: lightcoral;
  width: 400px;
}

.Parent>div {
  flex: 1;
  min-height: 100px;
}

.Parent > div:nth-child(odd) {
  background-color: lightblue;
}

.Parent > div:nth-child(even) {
  background-color: lightgreen;
}

<div class="Parent">
  <div class="child1">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam sagittis lorem at odio euismod tincidunt. Proin aliquet velit nec augue venenatis laoreet. Etiam nec metus mi. Aliquam sit amet velit non lectus porttitor accumsan sit amet egestas risus. Nullam sagittis lorem at odio euismod tincidunt. Proin aliquet velit nec augue venenatis laoreet. Etiam nec metus mi. Aliquam sit amet velit non lectus porttitor accumsan sit amet egestas risus.</div>
  <div class="child2">Lorem ipsum</div>
  <div>Lorem ipsum doler sit amet</div>
  <div>When there is little content in the children divs, the divs should be of equal height.</div>
</div>