html - Make flex items have equal width in a row

Question

If you look at the example below, I want the headers (h4.child-title) to have the same length within the parent container.

But I'm not successful in achieving this.

Any help is appreciated.

.top-level {
  display: flex;
  flex-flow: row wrap;
}

.section {
  display: flex;
  flex-flow: row nowrap;
  border: 1px solid;
  margin-right: 12px;
  margin-top: 12px;
}

.section-child {
  display: flex;
  flex-flow: column nowrap;
  align-items: center;
  flex: 1 1 0;
}

.child-title {
  white-space: nowrap;
}

.vertical-separator {
  width: 1px;
  background-color: rgba(0, 0, 0, 0.3);
  margin: 8px;
}

<div class="top-level">
  <section class="section">
    <div claas="section-child">
      <h4 class="child-title">Title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Longer title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Much much longer title</h4>
      <!--A lot more content here-->
    </div>
  </section>
  <section class="section">
    <div claas="section-child">
      <h4 class="child-title">Title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Longer title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Much much longer title</h4>
      <!--A lot more content here-->
    </div>
  </section>
  <section class="section">
    <div claas="section-child">
      <h4 class="child-title">Title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Longer title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Much much longer title</h4>
      <!--A lot more content here-->
    </div>
  </section>
</div>

Answer 1

Flexbox method

In order to make the text items (.section-child) equal width, you need to use flex: 1 1 0, which you have done. This is the same as saying flex: 1.

However, this by itself doesn't achieve the goal for two reasons:

1. The parent of .section-child, a flex container, but also a flex item in a larger container, is limited to the width of its content, by default. So it won't expand and the text can overflow the container. You need to apply flex: 1 to .section, as well.

2. A flex item cannot be smaller than the size of its content, by default. The initial setting is min-width: auto. So flex: 1 cannot work to equally distribute container space, because a flex item cannot shrink past the longest item. You need to override this behavior with min-width: 0.

.top-level {
  display: flex;
  flex-flow: row wrap;
}

.section {
  display: flex;
  flex-flow: row nowrap;
  border: 1px solid;
  margin-right: 12px;
  margin-top: 12px;
  flex: 1;
  min-width: 0;
}

.section-child {
  display: flex;
  flex-flow: column nowrap;
  align-items: center;
  flex: 1;
  min-width: 0;
}

.child-title {
  white-space: nowrap;
}

.vertical-separator {
  width: 1px;
  background-color: rgba(0, 0, 0, 0.3);
  margin: 8px;
}

<div class="top-level">
  <section class="section">
    <div class="section-child">
      <h4 class="child-title">Title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Longer title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Much much longer title</h4>
      <!--A lot more content here-->
    </div>
  </section>
  <section class="section">
    <div class="section-child">
      <h4 class="child-title">Title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Longer title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Much much longer title</h4>
      <!--A lot more content here-->
    </div>
  </section>
  <section class="section">
    <div class="section-child">
      <h4 class="child-title">Title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Longer title</h4>
      <!--A lot more content here-->
    </div>
    <div class="vertical-separator"></div>
    <div class="section-child">
      <h4 class="child-title">Much much longer title</h4>
      <!--A lot more content here-->
    </div>
  </section>
</div>