.er-card {
  max-width: 420px;
  margin: 0 auto;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 8px;
}
.er-title {
  font-weight: 700;
  margin-bottom: 0.5rem;
}
.er-clue {
  opacity: 0.85;
  margin-bottom: 0.75rem;
  line-height: 1.45;
}
.er-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.6rem;
}
.er-row input {
  flex: 1;
  min-width: 120px;
  padding: 0.45rem 0.6rem;
  font-size: 1.1rem;
  letter-spacing: 0.15em;
  text-align: center;
}
.er-sym {
  min-width: 3rem;
  min-height: 3rem;
  font-size: 1.4rem;
}
.er-seq {
  min-width: 2.6rem;
  min-height: 2.6rem;
  font-weight: 700;
}
.er-seq.on {
  outline: 2px solid var(--accent, #0a7a6f);
}