html - flexbox 边距导致溢出

Question

我有一个 flexbox 溢出的小问题:

html

<div class="first">
            <div class="child"></div>
            <div class="child"></div>
            <div class="child"></div>
</div>

CSS

* {
    box-sizing: border-box;
}

body {
    margin: 50px;
}
.first {
    display: flex;
    flex-flow: row nowrap;
}

.child {
    background: red;
    border: 1px blue solid;
    height: 10px;
    flex: 0 0 33.3%;

    margin-right: 10px;
}

.first :last-child {
    flex: 0 0 33.4%;
}

问题是最后一个 child 溢出了，为什么？？我使用了 box-sizing 到 border-box？

Answer 1

How to add margin between children without causing the overflow

我想这就是你想要做的:

* {
  box-sizing: border-box;
}

body {
  margin: 50px;
}

.first {
  display: flex;
  flex-flow: row nowrap;
  border:1px solid green;
}

.child {
  background: red;
  border: 1px blue solid;
  height: 10px;
  flex: 1; /* equal widths */
  margin-right: 10px;
}
.first :last-child {
  margin-right: 0;
}

<div class="first">
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
</div>

或者，您可以使用 calc 设置子宽度，并在 flex-container 上使用 justify-content:space-between

* {
  box-sizing: border-box;
}
body {
  margin: 50px;
}
.first {
  display: flex;
  flex-flow: row nowrap;
  border: 1px solid green;
  justify-content: space-between;
}
.child {
  background: red;
  border: 1px blue solid;
  height: 10px;
  width: calc((100% - 20px)/3);
  /* or */
  flex: 0 0 calc((100% - 20px)/3);
}

<div class="first">
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
</div>