scroll-padding-block-start

scroll-padding-block-start: 0;

scroll-padding-block-start: 20px;

scroll-padding-block-start: 2em;

<section class="default-example" id="default-example">
  <div class="scroller" id="example-element">
    <div>1</div>
    <div>2</div>
    <div>3</div>
  </div>
  <div class="info">スクロール »</div>
</section>

.default-example .info {
  inline-size: 100%;
  padding: 0.5em 0;
  font-size: 90%;
  writing-mode: vertical-rl;
}
.scroller {
  text-align: left;
  height: 250px;
  width: 270px;
  overflow-y: scroll;
  display: flex;
  flex-direction: column;
  box-sizing: border-box;
  border: 1px solid black;
  scroll-snap-type: y mandatory;
}
.scroller > div {
  flex: 0 0 250px;
  background-color: rebeccapurple;
  color: #fff;
  font-size: 30px;
  display: flex;
  align-items: center;
  justify-content: center;
  scroll-snap-align: start;
}
.scroller > div:nth-child(even) {
  background-color: #fff;
  color: rebeccapurple;
}

/* キーワード値 */
scroll-padding-block-start: auto;
/* <length> 値 */
scroll-padding-block-start: 10px;
scroll-padding-block-start: 1em;
scroll-padding-block-start: 10%;
/* グローバル値 */
scroll-padding-block-start: inherit;
scroll-padding-block-start: initial;
scroll-padding-block-start: revert;
scroll-padding-block-start: revert-layer;
scroll-padding-block-start: unset;