<h1><code>justify-content: flex-start</code></h1>
<div class="container flex-start">
      <div class="item item-1">1</div>
      <div class="item item-2">2</div>
      <div class="item item-3">3</div>
      <div class="item item-4">4</div>
</div>

<h1><code>justify-content: flex-end</code></h1>
<div class="container flex-end">
      <div class="item item-1">1</div>
      <div class="item item-2">2</div>
      <div class="item item-3">3</div>
      <div class="item item-4">4</div>
</div>

<h1><code>justify-content: center</code></h1>
<div class="container center">
      <div class="item item-1">1</div>
      <div class="item item-2">2</div>
      <div class="item item-3">3</div>
      <div class="item item-4">4</div>
</div>

<h1><code>justify-content: space-between</code></h1>
<div class="container space-between">
      <div class="item item-1">1</div>
      <div class="item item-2">2</div>
      <div class="item item-3">3</div>
      <div class="item item-4">4</div>
</div>

<h1><code>justify-content: space-around</code></h1>
<div class="container space-around">
      <div class="item item-1">1</div>
      <div class="item item-2">2</div>
      <div class="item item-3">3</div>
      <div class="item item-4">4</div>
</div>

html {
  background: #fff7f6;
}
h1 {
  color: DarkSlateGrey;
  font-weight: normal;
  font-size: 1.5em;
}
/*-- --*/
.container {
  display: flex;
  flex-wrap: wrap;
  flex-direction: row;
}
.container.flex-start {
  justify-content: flex-start;
}
.container.flex-end {
  justify-content: flex-end;
}
.container.center {
  justify-content: center;
}
.container.space-between {
  justify-content: space-between;
}
.container.space-around {
  justify-content: space-around;
}
.item {
  font-size: 2rem;
  line-height: 1;
  text-align: center;
  padding: 3rem;
  background: mistyrose;
  border: 3px solid tomato;
  color: tomato;
  margin: 6px;
}