Inhalt strukturieren mit Flexbox

Flex row

Die Boxen

<div class="bigbox">
  <div class="box"></div>
  <div class="box grow"></div>
  <div class="box"></div>
  <div class="box"></div>
</div>

& Die zentrierte Flexbox

.bigbox{
  width: 100%;
  border: 2px solid yellowgreen;
  padding: 1em 1em 0 1em;
  display: flex;
  justify-content: center;
  align-items: center;
}
.box{
  width: 150px;
  height: 150px;
  margin: 0 1em 1em ;
  background-color: yellowgreen;
}
.grow{
flex-grow: 1;
}