<p class="sample01">backgroundで下線</p>

<p class="sample02">backgroundでマーカー</p>

<p class="sample03">backgroundでグラデーションの線</p>
.sample01{
  background: linear-gradient(transparent 90%, #AFEEEE 0%);
}

.sample02{
  background: linear-gradient(transparent 50%, #AFEEEE 0%);
}

.sample03{
  background: linear-gradient(transparent 10%, #AFEEEE 90%);
}

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