row-gap (grid-row-gap)

row-gap: 0;

row-gap: 1ch;

row-gap: 1em;

row-gap: 20px;

<section class="default-example" id="default-example">
  <div class="example-container">
    <div class="transition-all" id="example-element">
      <div>One</div>
      <div>Two</div>
      <div>Three</div>
      <div>Four</div>
      <div>Five</div>
    </div>
  </div>
</section>

#example-element {
  border: 1px solid #c5c5c5;
  display: grid;
  grid-template-columns: 1fr 1fr;
  width: 200px;
}
#example-element > div {
  background-color: rgba(0, 0, 255, 0.2);
  border: 3px solid blue;
}

/* Valeurs de longueur */
/* Type <largeur>      */
row-gap: 20px;
row-gap: 1em;
row-gap: 3vmin;
row-gap: 0.5cm;
/* Valeurs proportionnelles */
/* Type <pourcentage>       */
row-gap: 10%;
/* Valeurs globales */
row-gap: inherit;
row-gap: initial;
row-gap: revert;
row-gap: unset;

<div id="flexbox">
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
</div>

#flexbox {
  display: flex;
  flex-wrap: wrap;
  width: 300px;
  row-gap: 20px;
}
#flexbox > div {
  border: 1px solid green;
  background-color: lime;
  flex: 1 1 auto;
  width: 100px;
  height: 50px;
}

<div id="grid">
  <div></div>
  <div></div>
  <div></div>
</div>

#grid {
  display: grid;
  height: 200px;
  grid-template-columns: 200px;
  grid-template-rows: repeat(3, 1fr);
  row-gap: 20px;
}
#grid > div {
  border: 1px solid green;
  background-color: lime;
}