article h1,
aside h1,
nav h1,
section h1 {
  font-size: 2.25rem;
}

.flip-card { perspective: 1000px; aspect-ratio: 1/1; cursor: pointer; }
.flip-card-inner { transition: transform 0.6s; transform-style: preserve-3d; position: relative; width: 100%; height: 100%; }
.flip-card:hover .flip-card-inner, .flip-card.flipped .flip-card-inner { transform: rotateY(180deg); }
.flip-card-front, .flip-card-back { position: absolute; width: 100%; height: 100%; backface-visibility: hidden; display: flex; align-items: center; justify-content: center; }
.flip-card-back { transform: rotateY(180deg); }