body {
  margin: 0;
  font-family: 'PingFang SC', 'Microsoft YaHei', Arial, sans-serif;
  background: #f3faff;
  color: #333;
}
header {
  background: linear-gradient(90deg, #6ee7b7 0%, #a7c7ff 100%);
  padding: 1.2rem 0 0.6rem 0;
  text-align: center;
  border-bottom-left-radius: 2rem;
  border-bottom-right-radius: 2rem;
  box-shadow: 0 2px 8px rgba(0,0,0,0.04);
  position: relative;
}
h1 {
  font-size: 2.2rem;
  margin: 0;
  letter-spacing: 2px;
  color: #2d6a4f;
}
.en-title {
  font-size: 1rem;
  color: #409eff;
  margin-left: 0.5rem;
}
main {
  max-width: 480px;
  margin: 0 auto;
  padding: 1.5rem 1rem 2rem 1rem;
}
.mode-select {
  text-align: center;
  margin-top: 2rem;
}
.mode-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem;
  justify-content: center;
  margin-top: 1.5rem;
}
.mode-btn {
  background: linear-gradient(135deg, #f9d423 0%, #ff4e50 100%);
  color: #fff;
  font-size: 1.2rem;
  border: none;
  border-radius: 1.5rem;
  padding: 1rem 2.2rem;
  box-shadow: 0 2px 8px rgba(255, 78, 80, 0.08);
  cursor: pointer;
  transition: transform 0.1s, background 0.2s;
  outline: none;
}
.mode-btn:active {
  transform: scale(0.96);
  background: linear-gradient(135deg, #ff4e50 0%, #f9d423 100%);
}
.hidden {
  display: none;
}
footer {
  text-align: center;
  color: #aaa;
  font-size: 0.9rem;
  margin: 2rem 0 1rem 0;
}
@media (max-width: 600px) {
  h1 { font-size: 1.4rem; }
  main { padding: 1rem 0.5rem; }
  .mode-btn { font-size: 1rem; padding: 0.8rem 1.2rem; }
}

.game-status {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1.1rem;
  margin-bottom: 1rem;
  padding: 0.2rem 0.5rem;
}
.score {
  color: #ff9800;
  font-weight: bold;
}
.progress {
  color: #409eff;
}

.result-card {
  background: #fffbe6;
  border-radius: 1.5rem;
  box-shadow: 0 4px 16px rgba(255, 193, 7, 0.12);
  max-width: 340px;
  margin: 2rem auto 0 auto;
  padding: 2rem 1.5rem 1.5rem 1.5rem;
  text-align: center;
  animation: pop-in 0.5s;
}
.result-card h2 {
  color: #ff9800;
  margin-bottom: 1rem;
}
.result-card p {
  font-size: 1.1rem;
  margin: 0.5rem 0;
}
.result-comment {
  color: #43a047;
  font-size: 1.2rem;
  margin: 1rem 0 1.5rem 0;
}
.result-btns {
  display: flex;
  justify-content: center;
  gap: 1.2rem;
}
.result-btns button {
  background: linear-gradient(135deg, #6ee7b7 0%, #a7c7ff 100%);
  color: #333;
  font-size: 1.1rem;
  border: none;
  border-radius: 1.2rem;
  padding: 0.7rem 1.6rem;
  box-shadow: 0 2px 8px rgba(67, 160, 71, 0.08);
  cursor: pointer;
  transition: transform 0.1s, background 0.2s;
}
.result-btns button:active {
  transform: scale(0.96);
  background: linear-gradient(135deg, #a7c7ff 0%, #6ee7b7 100%);
}

.animated {
  animation: pop-in 0.4s;
}
@keyframes pop-in {
  0% { transform: scale(0.7); opacity: 0; }
  80% { transform: scale(1.08); opacity: 1; }
  100% { transform: scale(1); }
}

.feedback-anim {
  display: inline-block;
  font-size: 2.2rem;
  vertical-align: middle;
  animation: bounce 0.5s;
}
.feedback-anim.correct {
  color: #43a047;
}
.feedback-anim.wrong {
  color: #e53935;
}
@keyframes bounce {
  0% { transform: scale(0.7); }
  60% { transform: scale(1.2); }
  100% { transform: scale(1); }
}

/* 优化题目区和按钮的过渡 */
.vertical-problem, .horizontal-problem {
  margin: 1.2rem auto 1.2rem auto;
  font-size: 2rem;
  background: #fff;
  border-radius: 1.2rem;
  box-shadow: 0 2px 8px rgba(64, 158, 255, 0.08);
  width: 220px;
  padding: 1rem 0.5rem 0.7rem 0.5rem;
  text-align: right;
  letter-spacing: 2px;
  transition: box-shadow 0.2s;
}
.vertical-problem:active, .horizontal-problem:active {
  box-shadow: 0 4px 16px rgba(64, 158, 255, 0.16);
}

.keypad-answer {
  min-height: 2.2rem;
  font-size: 1.5rem;
  text-align: center;
  margin: 0.5rem 0 0.7rem 0;
  color: #409eff;
  letter-spacing: 2px;
  font-weight: bold;
}

#sound-toggle-btn {
  position: absolute;
  top: 1.2rem;
  right: 1.5rem;
  background: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1.5rem;
  width: 2.4rem;
  height: 2.4rem;
  box-shadow: 0 2px 8px rgba(64,158,255,0.08);
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
  outline: none;
  z-index: 10;
}
#sound-toggle-btn:active {
  background: #e0f7fa;
  transform: scale(0.92);
}

.vertical-problem.enhanced, .horizontal-problem.enhanced {
  display: inline-block;
  padding: 0.7rem 0.5rem 0.7rem 0.5rem;
  background: #fff;
  border-radius: 1.2rem;
  box-shadow: 0 2px 8px rgba(64, 158, 255, 0.08);
  margin: 1.2rem auto 1.2rem auto;
  font-size: 1.7rem;
  text-align: right;
}
.carry-row {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 0.1rem;
}
.carry-cell {
  width: 2.1rem;
  height: 1.2rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  color: #ff9800;
  cursor: pointer;
  user-select: none;
  transition: background 0.15s;
  border-radius: 0.7rem;
}
.carry-cell:hover {
  background: #fff3e0;
}
.num-row {
  display: flex;
  justify-content: flex-end;
}
.num-cell {
  width: 2.1rem;
  height: 2.1rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  color: #333;
}
.answer-row {
  margin-top: 0.2rem;
}
.ans-cell {
  width: 2.1rem;
  height: 2.1rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: #409eff;
  background: #e3f2fd;
  border-radius: 0.7rem;
  margin: 0 0.05rem;
  border: 2px solid transparent;
  cursor: pointer;
  transition: border 0.15s, background 0.15s;
  user-select: none;
}
.ans-cell.active {
  border: 2px solid #409eff;
  background: #fffde7;
  color: #ff9800;
  box-shadow: 0 0 0 2px #ffe082;
}
.ans-cell:hover {
  background: #bbdefb;
}
.horizontal-problem.enhanced {
  font-size: 1.5rem;
  text-align: left;
  padding: 1rem 0.5rem 1rem 0.5rem;
}