数字と線を組み合わせた見出し – 半透明数字と下線

HTML

<h2 class="heading" data-number="01">採用情報について</h2>

CSS

.heading {
  position: relative;
  padding: 1em;
  font-size: 26px;
  border-bottom: 2px solid #e5c046;
}

.heading span {
  position: relative;
  z-index: 2;
}

.heading::before {
  content: attr(data-number);
  position: absolute;
  top: 0;
  left: 0;
  color: rgba(229 192 70 / .4);
  font-size: 54px;
  font-weight: 800;
  z-index: 1;
}