<style>
	.grid {
		display: grid;
		grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
		gap: 10px;
	}
	/* firefox용. about:config에서 layout.css.grid-template-masonry-value.enabled를 true로 해야 동작함  */
	@supports (grid-template-rows: masonry) {
		.grid {
			grid-template-rows: masonry;
		}
	}
	/* 사파리는 정식지원, chrome은 chrome://flags 에서 CSS Grid Lanes Layout를 enabled로 바꿔야 동작함 */
	@supports (display: grid-lanes) {
		.grid {
			display: grid-lanes;
		}
	}
	.item {
		background-color: pink;
		height: 100px;
	}
	.item.wide {
		grid-column: span 2;
	}
	.item.tall {
		height: 150px;
	}
	.item.tall2 {
		height: 200px;
	}
</style>

<div class="grid">
	<div class="item">1</div>
	<div class="item">2</div>
	<div class="item">3</div>
	<div class="item">4</div>
	<div class="item">5</div>
	<div class="item tall2 wide">6</div>
	<div class="item wide">7</div>
	<div class="item">8</div>
	<div class="item">9</div>
	<div class="item tall">10</div>
</div>

a {
  position: relative;
  color: #000;
  text-decoration: none;
}

a:hover {
  color: #000;
}

a::before {
  content: "";
  position: absolute;
  width: 100%;
  height: 2px;
  bottom: 0;
  left: 0;
  background-color: #000;
  visibility: hidden;
  transform: scaleX(0);
  transition: all 0.3s ease-in-out 0s;
}

a:hover::before {
  visibility: visible;
  transform: scaleX(1);
}

출처: tobiasahlin.com/blog/css-trick-animating-link-underlines/