body {
  font-family: "Yu Gothic", "Yu Gothic UI", "Meiryo", "Hiragino Sans", sans-serif;
  font-weight: 500;
}

li {
  margin-bottom: 0.25rem;
}

details {
  margin: 0.8rem 0 1.2rem 0;
}

details summary {
  color: inherit;
  font-weight: 600;
  cursor: pointer;
  margin-bottom: 0.4rem;
}

details[open] summary {
  margin-bottom: 0.6rem;
}

details ul {
  margin-top: 0.4rem;
}

.problem-button-row {
  display: flex;
  justify-content: flex-end;
  margin: 0.1rem 0 0.6rem 0;
}

.problem-button {
  color: inherit;
  background-color: transparent;
  border: 1px solid currentColor;
  border-radius: 0.3rem;
  padding: 0.2rem 0.6rem;
  font-size: 0.85rem;
  cursor: pointer;
  opacity: 0.75;
}

.problem-button:hover {
  opacity: 1;
  background-color: rgba(255, 255, 255, 0.08);
}