.exercise-contents {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.75rem;
  padding: 1.5rem;
  max-width: 1400px;
  margin: 0 auto;
}

.exercise-item {
  display: flex;
  flex-direction: column;
  /* background: #fdfcfa; */
  background: var(--color-background-neutral);
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--color-border-neutral);
  /* box-shadow: 0 2px 6px rgba(0, 0, 0, 0.03); */
  height: 100%;
}

.exercise-headline {
  display: flex;
  align-items: center;
  padding: 1rem 1.25rem;
  flex-shrink: 0;
  border-bottom: 2px solid #f1f5f9;
}

.exercise-number {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 2px solid #ea580c;
  color: #ea580c;
  display: flex;
  justify-content: center;
  align-items: center;
  font-weight: bold;
  font-size: 1.125rem;
  margin-right: 1rem;
  flex-shrink: 0;
  background: none;
  box-sizing: border-box;
}

.exercise-title {
  font-size: 1.125rem;
  font-weight: 700;
  color: #1e293b;
  line-height: 1.4;
  margin: 0;
  flex: 1;
}

.exercise-item img {
  width: 100%;
  height: 180px; /* 固定高さで統一 */
  object-fit: contain;
  object-position: center;
  /* background-color: #f8fafc; */
  display: block;
  padding: 0.75rem;
  box-sizing: border-box;
}

/* スマホ最適化 */
@media (max-width: 480px) {
  .exercise-contents {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.5rem;
    padding: 1rem;
  }

  .exercise-headline {
    padding: 1rem 1.25rem;
  }

  .exercise-number {
    width: 32px;
    height: 32px;
    font-size: 1rem;
    margin-right: 0.75rem;
    border-width: 1.5px;
  }

  .exercise-title {
    font-size: 1rem;
  }

  .exercise-item img {
    height: 150px; /* スマホ用に調整 */
    padding: 0.5rem;
  }
}