<h2>flex-shrink: 0</h2>
<div class="flex">
  <div class="item item-0"></div>
</div>

<h2>flex-shrink: 1</h2>
<div class="flex">
  <div class="item item-1"></div>
</div>

.flex {
  border: 1px solid #000;
  display: flex;
  width: 50%;
  padding: 0 4px;
}
.item {
  flex-shrink: 0;
  
  &.item-1 {
    flex-shrink: 1;
  }
  
  box-sizing: border-box;
  width: 180%;
  margin: 8px 4px;
  padding: 64px 0;
  background: #faa;
}