<div class="flex-container">
  <div class="item1">3/0/100px</div>
  <div class="item2">2/0/100px</div>
  <div class="item3">1/0/100px</div>
</div>
.flex-container {
  display:flex;
  width:480px;
  justify-content: space-between;
}
.flex-container div{
    height:40px;
}
.item1{
  background: #484281;
  flex:3 0 100px;
}
.item2{
  background: #5248af;
  flex:2 0 100px;
}
.item3{
  background: #786bfa;
  flex:1 0 100px;
}

External CSS

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External JavaScript

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