place-items

place-items: center stretch;

place-items: center start;

place-items: start end;

place-items: end center;

<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>
  </div>
</section>

#example-element {
  border: 1px solid #c5c5c5;
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-auto-rows: 80px;
  grid-gap: 10px;
  width: 220px;
}
#example-element > div {
  background-color: rgba(0, 0, 255, 0.2);
  border: 3px solid blue;
}

/* キーワード値 */
place-items: center;
place-items: normal start;
place-items: center normal;
place-items: start legacy;
place-items: end normal;
place-items: self-start legacy;
place-items: self-end normal;
place-items: flex-start legacy;
place-items: flex-end normal;
place-items: anchor-center;
/* ベースラインによる配置 */
place-items: baseline normal;
place-items: first baseline legacy;
place-items: last baseline normal;
place-items: stretch legacy;
/* グローバル値 */
place-items: inherit;
place-items: initial;
place-items: revert;
place-items: revert-layer;
place-items: unset;

div > div {
  box-sizing: border-box;
  border: 2px solid #8c8c8c;
  width: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
}
#item1 {
  background-color: #8cffa0;
  min-height: 30px;
  font-size: 2em;
}
#item2 {
  background-color: #a0c8ff;
  min-height: 50px;
}
#item3 {
  background-color: #ffa08c;
  min-height: 40px;
}
#item4 {
  background-color: #ffff8c;
  min-height: 60px;
}
#item5 {
  background-color: #ff8cff;
  min-height: 70px;
}
#item6 {
  background-color: #8cffff;
  min-height: 50px;
}
select {
  font-size: 16px;
}
.row {
  margin-top: 10px;
}

<div id="container">
  <div id="item1">1</div>
  <div id="item2">2</div>
  <div id="item3">3</div>
</div>
<div class="row">
  <label for="values">place-items: </label>
  <select id="values">
    <option value="stretch">stretch</option>
    <option value="start">start</option>
    <option value="center">center</option>
    <option value="end">end</option>
    <option value="left">left</option>
    <option value="right">right</option>
    <option value="auto center">auto center</option>
    <option value="normal start">normal start</option>
    <option value="center normal">center normal</option>
    <option value="start auto">start auto</option>
    <option value="end normal">end normal</option>
    <option value="self-start auto">self-start auto</option>
    <option value="self-end normal">self-end normal</option>
    <option value="flex-start auto">flex-start auto</option>
    <option value="flex-end normal">flex-end normal</option>
    <option value="left auto">left auto</option>
    <option value="right normal">right normal</option>
    <option value="baseline normal">baseline normal</option>
    <option value="first baseline auto">first baseline auto</option>
    <option value="last baseline normal">last baseline normal</option>
    <option value="stretch auto">stretch auto</option>
  </select>
</div>

const values = document.getElementById("values");
const container = document.getElementById("container");
values.addEventListener("change", (evt) => {
  container.style.placeItems = evt.target.value;
});

#container {
  height: 200px;
  width: 240px;
  place-items: stretch; /* リストの選択肢を変更することで、この値を変更できます */
  background-color: #8c8c8c;
  display: flex;
}

div > div {
  box-sizing: border-box;
  border: 2px solid #8c8c8c;
}
#item1 {
  background-color: #8cffa0;
  min-height: 30px;
  font-size: 2em;
}
#item2 {
  background-color: #a0c8ff;
  min-height: 50px;
}
#item3 {
  background-color: #ffa08c;
  min-height: 40px;
}
#item4 {
  background-color: #ffff8c;
  min-height: 60px;
}
#item5 {
  background-color: #ff8cff;
  min-height: 70px;
}
#item6 {
  background-color: #8cffff;
  min-height: 50px;
}
select {
  font-size: 16px;
}
.row {
  margin-top: 10px;
}

<div id="grid-container">
  <div id="item1">1</div>
  <div id="item2">2</div>
  <div id="item3">3</div>
  <div id="item4">4</div>
  <div id="item5">5</div>
</div>
<div class="row">
  <label for="grid-values">place-items: </label>
  <select id="grid-values">
    <option value="stretch">stretch</option>
    <option value="start">start</option>
    <option value="center">center</option>
    <option value="end">end</option>
    <option value="left">left</option>
    <option value="right">right</option>
    <option value="auto center">auto center</option>
    <option value="normal start">normal start</option>
    <option value="center normal">center normal</option>
    <option value="start auto">start auto</option>
    <option value="end normal">end normal</option>
    <option value="self-start auto">self-start auto</option>
    <option value="self-end normal">self-end normal</option>
    <option value="flex-start auto">flex-start auto</option>
    <option value="flex-end normal">flex-end normal</option>
    <option value="left auto">left auto</option>
    <option value="right normal">right normal</option>
    <option value="baseline normal">baseline normal</option>
    <option value="first baseline auto">first baseline auto</option>
    <option value="last baseline normal">last baseline normal</option>
    <option value="stretch auto">stretch auto</option>
  </select>
</div>

const values = document.getElementById("grid-values");
const container = document.getElementById("grid-container");
values.addEventListener("change", (evt) => {
  container.style.placeItems = evt.target.value;
});

#grid-container {
  height: 200px;
  width: 240px;
  place-items: stretch; /* リストの選択肢を変更することで、この値を変更できます */
  background-color: #8c8c8c;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
}
#grid-container > div {
  width: 50px;
}