Inline flex container (display: inline-flex) is expanding the full width of parent container

Question

I have a DIV with display: block (.out).

In this DIV there is a flexbox with display: inline-flex (.row) that has

Answer 1

If i understand right, margin or align-self should do it:

• align-self https://jsfiddle.net/2ymx9oog/1/

.out {
  border: 1px solid red;
  display: block;
  position: fixed;
  top: 0;
  left: 0;
}

.row {
  display: inline-flex;
  flex-direction: row;
  padding: 10px;
  border: 1px solid yellow;
}
.infos {
  border: 1px solid green;
  flex-basis: 350px;
}
.dynamic {
  border: 1px solid blue;
  flex: 1 1;
  align-self:flex-start
}

<div class="out">
<div class="row">
    <div class="infos">
      Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit a
    </div>
    <div class="dynamic">
    Lorem ipsum
    </div>
  </div>
  
</div>

• margin-bottom in this case https://jsfiddle.net/2ymx9oog/2/

.out {
  border: 1px solid red;
  display: block;
  position: fixed;
  top: 0;
  left: 0;
}
.row {
  display: inline-flex;
  flex-direction: row;
  padding: 10px;
  border: 1px solid yellow;
}
.infos {
  border: 1px solid green;
  flex-basis: 350px;
}
.dynamic {
  border: 1px solid blue;
  flex: 1 1;
  margin-bottom: auto
}

<div class="out">
  <div class="row">
    <div class="infos">
      Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata
      sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea
      rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit a
    </div>
    <div class="dynamic">
      Lorem ipsum
    </div>
  </div>

</div>

if it is about the width too, then remove the flex property : https://jsfiddle.net/2ymx9oog/4/

For both earlier example see results here :

• margin https://jsfiddle.net/2ymx9oog/3/
• align-self https://jsfiddle.net/2ymx9oog/5/

You can play with margin or align-self

example with margin:auto without flex values set https://jsfiddle.net/2ymx9oog/6/ set your dynamic box in the middle within the right area

You may set it at middle top, at middle middle, middle bottom, left top, left bottom, left middle, and so on

Answer 2

Use width: 350px instead of flex-basis: 350px.

In your code, .row is first sized summing the width of its contents. Since .infos has no width, its initial size is given by its very long content. So .row fills all the available space in its containing block. It's after the size of .row has been determined that the flex items do flex and .infos becomes 350px. But then it's too late, .row is already too wide.

If you use width: 350px, .row will be sized using that value, without taking extra space.

.out {
  border: 1px solid red;
  display: block;
  position: fixed;
  top: 0;
  left: 0;
}
.row {
  display: inline-flex;
  flex-direction: row;
  padding: 10px;
  border: 1px solid yellow;
}
.infos {
  border: 1px solid green;
  width: 350px;
}
.dynamic {
  border: 1px solid blue;
  flex: 1 1;
}

<div class="out">
  <div class="row">
    <div class="infos">
      Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata
      sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea
      rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit a
    </div>
    <div class="dynamic">
      Lorem ipsum
    </div>
  </div>

</div>