.board-wrap {
  position: relative;
  width: min(92vw, 480px);
  margin: 0 auto;
}

.problem-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  padding: 40px 24px;
  background: linear-gradient(135deg, #ff8b94, #ee5a52);
  border-radius: 24px;
  color: #fff;
  user-select: none;
  min-height: 320px;
  text-align: center;
  transition: transform 0.1s, box-shadow 0.15s;
  box-shadow: 0 10px 30px rgba(255, 139, 148, 0.25);
}

.problem-card.correct {
  background: linear-gradient(135deg, #2ed573, #26b562);
  animation: pop 0.3s ease;
}

.problem-card.wrong {
  background: linear-gradient(135deg, #ff4757, #c0392b);
  animation: shake 0.35s ease;
}

@keyframes pop {
  0%, 100% { transform: scale(1); }
  50%      { transform: scale(1.04); }
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25%      { transform: translateX(-10px); }
  75%      { transform: translateX(10px); }
}

.problem-text {
  font-size: clamp(2.6rem, 11vw, 4rem);
  font-weight: 900;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.06em;
}

.problem-equals {
  font-size: clamp(1.8rem, 7vw, 2.6rem);
  font-weight: 800;
  opacity: 0.9;
}

#answer {
  width: min(70vw, 220px);
  padding: 14px 20px;
  background: rgba(255,255,255,0.18);
  color: #fff;
  border: 2px solid rgba(255,255,255,0.4);
  border-radius: 14px;
  font-size: clamp(1.6rem, 6.5vw, 2.2rem);
  font-weight: 800;
  font-family: inherit;
  text-align: center;
  font-variant-numeric: tabular-nums;
  outline: none;
  transition: border-color 0.15s, background 0.15s;
  -moz-appearance: textfield;
}
#answer::-webkit-outer-spin-button,
#answer::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

#answer:focus {
  background: rgba(255,255,255,0.28);
  border-color: rgba(255,255,255,0.7);
}

#answer::placeholder { color: rgba(255,255,255,0.5); }
#answer:disabled { opacity: 0.55; cursor: not-allowed; }

#status-label.playing { color: #2ed573; }
#status-label.warn { color: #ff6b6b; }

.stat-value.warn { color: #ff6b6b; }

/* ===== 시작 오버레이 ===== */

.math-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(15, 23, 41, 0.78);
  backdrop-filter: blur(8px);
  border-radius: 24px;
  z-index: 5;
  transition: opacity 0.2s;
}

.math-overlay.hidden {
  opacity: 0;
  pointer-events: none;
}

.overlay-content {
  text-align: center;
  padding: 24px;
}

.overlay-icon { font-size: 3.5rem; margin-bottom: 12px; }
.overlay-content h2 { font-size: 1.5rem; font-weight: 800; margin-bottom: 6px; }
.overlay-content p { color: var(--text-dim); margin-bottom: 18px; }

.hint {
  text-align: center;
  margin-top: 20px;
  color: var(--text-dim);
  font-size: 0.9rem;
}

/* ===== 결과 모달 ===== */

.result-modal {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 41, 0.85);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  z-index: 50;
  animation: fadeIn 0.25s ease;
}

.result-modal.hidden { display: none; }

@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }

.result-card {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 32px 28px;
  max-width: 420px;
  width: 100%;
  text-align: center;
  box-shadow: var(--shadow);
  animation: slideUp 0.3s ease;
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(30px); }
  to   { opacity: 1; transform: translateY(0); }
}

.result-emoji { font-size: 4rem; margin-bottom: 8px; }
.result-card h2 { font-size: 1.5rem; margin-bottom: 8px; }
.result-msg { color: var(--text-dim); margin-bottom: 24px; }

.result-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 12px;
}

.result-stats > div {
  background: rgba(255,255,255,0.05);
  padding: 14px;
  border-radius: 12px;
}

.result-stats span {
  display: block;
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.result-stats strong {
  font-size: 1.6rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.result-rank {
  font-size: 1.05rem;
  font-weight: 700;
  margin: 8px 0 4px;
  color: var(--accent);
}

.result-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 20px;
}

.result-actions .btn {
  padding: 12px 16px;
  text-align: center;
  font-size: 0.95rem;
}