I have a parent div, there are two divs inside it. Div .child-long has a width set as a percentage, and div .child-short has a static width set in pixels.
How to make .child-long not "shrink" .child-short but shrinks itself?
.parent{
  width: 100%;
  height: 200px;
  border: solid green 2px;
  margin: 10px;
  padding: 10px;
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: space-between;
}
.child-long{
  height: 100%;
  width: 90%;
  background-color: red;
}
.child-short{
  height: 100%;
  width: 400px;
  background-color: green;
}<div class="parent">
  <div class="child-long"></div>
  <div class="child-short"></div>
</div>