<div class="flex-container space-between" style="width: 100%; justify-content: space-around;">
  <div class="side flex-col flex-container">
    <h1>Gap between items with direction = <u><i>row</i></u></h1>
    
    <h2>gap: 20px <small>(set the gap between columns & rows to 20px)</small></h2>
    <div class="flex-wrap flex-container" style="gap: 20px">
      <div>1</div>
      <div>2</div>
      <div>3</div>
    </div>
    
    <h2>gap: 10px 20px <small>(gap composition when the first value repsents rows gap & the second value is for column gap)</small></h2>
    <div class="flex-wrap flex-container" style="gap: 10px 20px">
      <div>1</div>
      <div>2</div>
      <div>3</div>
    </div>
    
    <h2>column-gap: 20px </h2>
    <div class="flex-wrap flex-container" style="column-gap: 20px">
      <div>1</div>
      <div>2</div>
      <div>3</div>
    </div>
    
    <h2>row-gap: 20px </h2>
    <div class="flex-wrap flex-container" style="row-gap: 20px">
      <div>1</div>
      <div>2</div>
      <div>3</div>
    </div>
  </div>
</div>

.flex-container {
  display: flex;
  margin-bottom: 15px;
}

.flex-wrap {
  flex-wrap: wrap;
}

/* General styles */

small {
  font-size: .75em;
  display: block;
  font-style: italic;
  color: gray;
}

.flex-row {
  flex-direction: row;
}

.flex-col {
  flex-direction: column;
}

.side {
  min-width: 250px;
}

.side + .side {
  margin-left: 15px;
}

.side .flex-container {
  background-color: lightblue;
  border: 2px solid #000;
}

.side .flex-container div {
  background-color: lightgreen;
  padding: 10px;
  text-align:center;
  border: 2px solid lightblue;
  flex: 0 0 40%;
}

h1, h2 {
  margin-top: 0;
}