#tool-body {
  font-family: "Comic Sans MS", "Segoe UI", cursive, sans-serif;
  max-width: 700px;
  margin: 0 auto;
  --primary: #4D96FF;
  --primary-dark: #3a7bd5;
  --primary-shadow: 0 4px 0 #2465cc;
  --danger: #FF6B6B;
  --success: #6BCB77;
  --warning: #FF9F43;
  --card-bg: #fff;
  --text-muted: #666;
  --border-color: #e8e8e8;
  --kbd-bg: #f5f8ff;
  --kbd-shadow: 0 4px 0 #c0d5ff;
  --kbd-hover: #e0ebff;
  --radius: 18px;
  --shadow: 0 6px 24px rgba(0, 0, 0, 0.08);
  --transition: 0.2s ease;
  color: #222;
}
.theme-dark-mode #tool-body {
  --card-bg: #2d2d2d;
  --text-muted: #b0b0b0;
  --border-color: #444;
  --kbd-bg: #3a3a3a;
  --kbd-shadow: 0 4px 0 #222;
  --kbd-hover: #484848;
  --shadow: 0 6px 24px rgba(0, 0, 0, 0.4);
  color: #eee;
}

#tool-body * {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ========== 卡片 ========== */
#tool-body .math-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px 20px;
  box-shadow: var(--shadow);
  transition: background var(--transition);
}

/* ========== 配置界面 ========== */
#tool-body .config-section {
  display: block;
}
#tool-body .config-section.hidden {
  display: none;
}

#tool-body .config-title {
  font-size: 26px;
  font-weight: 700;
  color: var(--primary);
  text-align: center;
  margin-bottom: 20px;
  letter-spacing: 1px;
}
#tool-body .config-title small {
  font-size: 14px;
  font-weight: 400;
  color: var(--text-muted);
  display: block;
  margin-top: 10px;
  margin-bottom: 30px;
}

#tool-body .config-group {
  margin-bottom: 30px;
}
#tool-body .config-label {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}
#tool-body .config-label .badge {
  font-size: 12px;
  background: var(--primary);
  color: #fff;
  border-radius: 10px;
  padding: 0 10px;
  line-height: 20px;
  font-weight: 400;
}

/* 運算類型按鈕組 */
#tool-body .op-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
#tool-body .op-btn {
  background: var(--kbd-bg);
  border: 2px solid var(--border-color);
  border-radius: 24px;
  padding: 8px 20px;
  font-size: 16px;
  font-family: inherit;
  cursor: pointer;
  color: var(--text-muted);
  transition: all var(--transition);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  /*   flex: 1 0 auto; */
  min-width: 60px;
  text-align: center;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}
#tool-body .op-btn i {
  font-size: 18px;
}
#tool-body .op-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}
#tool-body .op-btn:hover:not(.active) {
  border-color: var(--primary);
  color: var(--primary);
}
#tool-body .op-btn:active {
  transform: scale(0.96);
}

/* 預設範圍 */
#tool-body .range-presets {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 8px;
}
#tool-body .range-preset {
  background: var(--kbd-bg);
  border: 2px solid var(--border-color);
  border-radius: 20px;
  padding: 4px 16px;
  font-size: 14px;
  font-family: inherit;
  cursor: pointer;
  color: var(--text-muted);
  transition: all var(--transition);
  user-select: none;
}
#tool-body .range-preset.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}
#tool-body .range-preset:hover:not(.active) {
  border-color: var(--primary);
  color: var(--primary);
}

#tool-body .range-custom {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 6px;
}
#tool-body .range-custom input {
  width: 64px;
  padding: 6px 8px;
  border: 2px solid var(--border-color);
  border-radius: 12px;
  font-size: 15px;
  font-family: inherit;
  background: var(--card-bg);
  color: inherit;
  text-align: center;
  outline: none;
  transition: border var(--transition);
}
#tool-body .range-custom input:focus {
  border-color: var(--primary);
}
#tool-body .range-custom span {
  color: var(--text-muted);
  font-size: 16px;
}

/* 高級選項 */
#tool-body .adv-group {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}
#tool-body .adv-check {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 15px;
  color: var(--text-muted);
  cursor: pointer;
  user-select: none;
}
#tool-body .adv-check input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--primary);
  cursor: pointer;
  flex-shrink: 0;
}

/* 題目數量 */
#tool-body .count-group {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}
#tool-body .count-btn {
  background: var(--kbd-bg);
  border: 2px solid var(--border-color);
  border-radius: 20px;
  padding: 4px 16px;
  font-size: 14px;
  font-family: inherit;
  cursor: pointer;
  color: var(--text-muted);
  transition: all var(--transition);
  user-select: none;
}
#tool-body .count-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}
#tool-body .count-btn:hover:not(.active) {
  border-color: var(--primary);
  color: var(--primary);
}
#tool-body .count-custom {
  display: flex;
  align-items: center;
  gap: 4px;
}
#tool-body .count-custom input {
  width: 80px;
  padding: 6px 8px;
  border: 2px solid var(--border-color);
  border-radius: 12px;
  font-size: 15px;
  font-family: inherit;
  background: var(--card-bg);
  color: inherit;
  text-align: center;
  outline: none;
  transition: border var(--transition);
}
#tool-body .count-custom input:focus {
  border-color: var(--primary);
}
#tool-body .count-custom span {
  color: var(--text-muted);
  font-size: 14px;
}

/* 開始按鈕 */
#tool-body .start-btn-wrap {
  text-align: center;
  margin-top: 12px;
}
#tool-body .start-btn {
  background: var(--primary);
  border: none;
  border-radius: 30px;
  padding: 14px 48px;
  font-size: 20px;
  font-family: inherit;
  color: #fff;
  cursor: pointer;
  box-shadow: var(--primary-shadow);
  transition: all var(--transition);
  letter-spacing: 2px;
  font-weight: 700;
}
#tool-body .start-btn:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 0 #1a4a8a;
}
#tool-body .start-btn:active {
  transform: translateY(3px);
  box-shadow: none;
}
#tool-body .start-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
  box-shadow: var(--primary-shadow);
}

/* 配置底部操作 */
#tool-body .config-actions {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 14px;
  flex-wrap: wrap;
}
#tool-body .config-actions .action-btn {
  background: none;
  border: 2px solid var(--border-color);
  border-radius: 20px;
  padding: 6px 22px;
  font-size: 15px;
  font-family: inherit;
  cursor: pointer;
  color: var(--text-muted);
  transition: all var(--transition);
}
#tool-body .config-actions .action-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}
#tool-body .config-actions .action-btn.history-btn {
  border-color: var(--danger);
  color: var(--danger);
}
#tool-body .config-actions .action-btn.history-btn:hover {
  background: var(--danger);
  color: #fff;
}

/* ========== 做題界面 ========== */
#tool-body .play-section {
  display: none;
}
#tool-body .play-section.active {
  display: block;
}

#tool-body .play-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
  font-size: 15px;
  color: var(--text-muted);
}
#tool-body .play-header .progress {
  font-weight: 600;
  color: var(--primary);
  font-size: 17px;
}
#tool-body .play-header .stats {
  display: flex;
  gap: 14px;
  align-items: center;
  font-size: 18px;
}
#tool-body .play-header .stats span {
  display: flex;
  align-items: center;
  gap: 4px;
}
#tool-body .play-header .stats .num-correct {
  color: var(--success);
  font-weight: 700;
  font-size: 18px;
}
#tool-body .play-header .stats .num-wrong {
  color: var(--danger);
  font-weight: 700;
  font-size: 18px;
}
#tool-body .play-header .stats .num-rate {
  color: var(--primary);
  font-weight: 700;
  font-size: 18px;
}

/* 題目區域 */
#tool-body .problem-area {
  text-align: center;
  margin: 6px 0 12px;
  padding: 10px 0;
}
#tool-body .problem-expr {
  font-size: 48px;
  color: var(--primary);
  line-height: 1.2;
  letter-spacing: 2px;
  font-weight: 700;
}
#tool-body .answer-display {
  font-size: 40px;
  color: var(--danger);
  min-height: 48px;
  border-bottom: 3px dashed var(--primary);
  display: inline-block;
  min-width: 80px;
  padding: 0 12px;
  letter-spacing: 2px;
  margin-top: 6px;
  font-weight: 600;
  transition: border-color 0.2s, color 0.2s;
}
#tool-body .answer-display.placeholder {
  color: #bbb;
}
#tool-body .answer-display.shake {
  animation: shakeInput 0.4s ease-in-out;
  border-color: var(--danger) !important;
  color: var(--danger) !important;
}
@keyframes shakeInput {
  0%,
  100% {
    transform: translateX(0);
  }
  20% {
    transform: translateX(-10px);
  }
  40% {
    transform: translateX(10px);
  }
  60% {
    transform: translateX(-6px);
  }
  80% {
    transform: translateX(6px);
  }
}

/* 反饋 + 跳過 */
#tool-body .feedback-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  min-height: 44px;
  margin: 6px 0 2px;
}
#tool-body .feedback {
  font-size: 20px;
  min-height: 32px;
  text-align: center;
  font-weight: 600;
}
#tool-body .feedback.correct {
  color: var(--success);
}
#tool-body .feedback.wrong {
  color: var(--danger);
  animation: blinkFeedback 0.6s ease;
}
@keyframes blinkFeedback {
  0%,
  100% {
    opacity: 1;
  }
  50% {
    opacity: 0.3;
  }
}
#tool-body .feedback.skip {
  color: var(--warning);
}
#tool-body .skip-btn {
  background: none;
  border: 2px solid var(--warning);
  border-radius: 20px;
  padding: 4px 18px;
  font-size: 15px;
  font-family: inherit;
  cursor: pointer;
  color: var(--warning);
  transition: all var(--transition);
  user-select: none;
  display: none;
  /* 默認隱藏 */;
}
#tool-body .skip-btn.visible {
  display: inline-block;
  animation: fadeInSkip 0.3s ease;
}
@keyframes fadeInSkip {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}
#tool-body .skip-btn:hover {
  background: var(--warning);
  color: #fff;
}
#tool-body .skip-btn:active {
  transform: scale(0.95);
}

/* 虛擬鍵盤 */
#tool-body .numpad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-top: 12px;
}
#tool-body .numpad-key {
  background: var(--kbd-bg);
  border: none;
  border-radius: 12px;
  box-shadow: var(--kbd-shadow);
  font-size: 28px;
  font-family: inherit;
  padding: 14px 0;
  cursor: pointer;
  color: var(--primary);
  transition: all 0.08s;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  font-weight: bold;
}
#tool-body .numpad-key:active,
#tool-body .numpad-key.pressed {
  transform: translateY(3px);
  box-shadow: none;
}
#tool-body .numpad-key:hover {
  background: var(--kbd-hover);
}
#tool-body .numpad-key.key-0 {
  grid-column: span 2;
}
#tool-body .numpad-key.key-del {
  color: var(--warning);
}
#tool-body .numpad-key.key-neg {
  color: var(--danger);
}
#tool-body .numpad-key.key-dot {
  color: var(--primary);
  font-size: 28px;
  font-weight: 700;
  padding: 0;
}
#tool-body .numpad-key.key-dot.disabled {
  opacity: 0.3;
  cursor: not-allowed;
  pointer-events: none;
}
#tool-body .numpad-key.key-enter {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 0 #2465cc;
  font-size: 22px;
  grid-column: span 1;
  grid-row: span 2;
  border-radius: 14px;
  font-weight: 700;
  letter-spacing: 1px;
  display: flex;
  align-items: center;
  justify-content: center;
}
#tool-body .numpad-key.key-enter:active {
  box-shadow: none;
}
.theme-dark-mode #tool-body .numpad-key.key-enter {
  box-shadow: 0 4px 0 #1a3a70;
}

/* 做題底部操作 */
#tool-body .play-actions {
  display: flex;
  justify-content: center;
  gap: 14px;
  margin-top: 16px;
  flex-wrap: wrap;
}
#tool-body .play-actions .action-btn {
  background: none;
  border: 2px solid var(--border-color);
  border-radius: 20px;
  padding: 7px 22px;
  font-size: 15px;
  font-family: inherit;
  cursor: pointer;
  color: var(--text-muted);
  transition: all var(--transition);
}
#tool-body .play-actions .action-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}
#tool-body .play-actions .action-btn.replay-btn {
  border-color: var(--danger);
  color: var(--danger);
}
#tool-body .play-actions .action-btn.replay-btn:hover {
  background: var(--danger);
  color: #fff;
}
#tool-body .play-actions .action-btn.history-btn {
  border-color: var(--primary);
  color: var(--primary);
}
#tool-body .play-actions .action-btn.history-btn:hover {
  background: var(--primary);
  color: #fff;
}

/* ========== 模態框 ========== */
#tool-body .modal {
  display: none;
  position: fixed;
  z-index: 9999;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.45);
  align-items: center;
  justify-content: center;
  padding: 16px;
  box-sizing: border-box;
  backdrop-filter: blur(3px);
}
#tool-body .modal.open {
  display: flex;
}
#tool-body .modal-content {
  background-color: var(--card-bg);
  color: inherit;
  padding: 24px 28px;
  border-radius: var(--radius);
  width: 100%;
  max-width: 560px;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  box-shadow: 0 12px 48px rgba(0, 0, 0, 0.25);
  position: relative;
  box-sizing: border-box;
  margin: 0 auto;
  animation: modalFadeIn 0.25s ease;
}
@keyframes modalFadeIn {
  from {
    opacity: 0;
    transform: scale(0.94) translateY(20px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}
#tool-body .modal-title {
  font-size: 22px;
  color: var(--primary);
  font-weight: 700;
  margin-bottom: 12px;
  padding-right: 32px;
}
#tool-body .modal-close {
  position: absolute;
  right: 18px;
  top: 14px;
  font-size: 28px;
  cursor: pointer;
  color: var(--text-muted);
  line-height: 1;
  background: none;
  border: none;
  font-family: inherit;
  transition: color var(--transition);
}
#tool-body .modal-close:hover {
  color: var(--danger);
}
#tool-body .modal-body {
  overflow-y: auto;
  overflow-x: auto;
  flex: 1;
  margin-top: 4px;
}

/* 總結彈窗 */
#tool-body .summary-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px 20px;
  margin: 8px 0 16px;
}
#tool-body .summary-item {
  text-align: center;
  padding: 12px 8px;
  background: var(--kbd-bg);
  border-radius: 14px;
}
#tool-body .summary-item .num {
  font-size: 32px;
  font-weight: 700;
}
#tool-body .summary-item .num.green {
  color: var(--success);
}
#tool-body .summary-item .num.red {
  color: var(--danger);
}
#tool-body .summary-item .num.blue {
  color: var(--primary);
}
#tool-body .summary-item .label {
  font-size: 14px;
  color: var(--text-muted);
  margin-top: 2px;
}
#tool-body .summary-actions {
  display: flex;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
  margin: 6px 0;
}
#tool-body .summary-actions .action-btn {
  background: none;
  border: 2px solid var(--border-color);
  border-radius: 20px;
  padding: 8px 28px;
  font-size: 16px;
  font-family: inherit;
  cursor: pointer;
  color: var(--text-muted);
  transition: all var(--transition);
}
#tool-body .summary-actions .action-btn.primary-btn {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  box-shadow: var(--primary-shadow);
}
#tool-body .summary-actions .action-btn.primary-btn:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
}
#tool-body .summary-actions .action-btn.primary-btn:active {
  transform: translateY(3px);
  box-shadow: none;
}
#tool-body .summary-actions .action-btn:hover:not(.primary-btn) {
  border-color: var(--primary);
  color: var(--primary);
}
#tool-body .summary-actions .action-btn.history-btn {
  border-color: var(--danger);
  color: var(--danger);
}
#tool-body .summary-actions .action-btn.history-btn:hover {
  background: var(--danger);
  color: #fff;
}

/* 歷史表格 */
#tool-body #historyTable {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}
#tool-body #historyTable th,
#tool-body #historyTable td {
  padding: 10px 8px;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}
#tool-body #historyTable th {
  background-color: var(--primary);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 2;
}
#tool-body #historyTable tr:nth-child(even) td {
  background-color: var(--kbd-bg);
}
#tool-body #historyTable .tag {
  display: inline-block;
  padding: 0 10px;
  border-radius: 10px;
  font-size: 12px;
  line-height: 20px;
  font-weight: 600;
}
#tool-body #historyTable .tag.correct {
  background: var(--success);
  color: #fff;
}
#tool-body #historyTable .tag.wrong {
  background: var(--danger);
  color: #fff;
}
#tool-body #historyTable .tag.skip {
  background: var(--warning);
  color: #fff;
}

/* ========== 確認對話框 ========== */
#tool-body .confirm-dialog .modal-content {
  max-width: 400px;
  text-align: center;
  padding: 28px 24px;
}
#tool-body .confirm-dialog .modal-title {
  text-align: center;
  padding-right: 0;
  font-size: 20px;
}
#tool-body .confirm-dialog .modal-body {
  font-size: 16px;
  color: var(--text-muted);
  padding: 8px 0 16px;
}
#tool-body .confirm-dialog .confirm-actions {
  display: flex;
  justify-content: center;
  gap: 14px;
}
#tool-body .confirm-dialog .confirm-actions button {
  border: none;
  border-radius: 20px;
  padding: 8px 32px;
  font-size: 16px;
  font-family: inherit;
  cursor: pointer;
  transition: all var(--transition);
}
#tool-body .confirm-dialog .confirm-actions .btn-cancel {
  background: var(--kbd-bg);
  color: var(--text-muted);
  border: 2px solid var(--border-color);
}
#tool-body .confirm-dialog .confirm-actions .btn-cancel:hover {
  border-color: var(--primary);
  color: var(--primary);
}
#tool-body .confirm-dialog .confirm-actions .btn-confirm {
  background: var(--danger);
  color: #fff;
  border: 2px solid var(--danger);
}
#tool-body .confirm-dialog .confirm-actions .btn-confirm:hover {
  background: #e55a5a;
}
#tool-body .confirm-dialog .confirm-actions .btn-confirm.primary {
  background: var(--primary);
  border-color: var(--primary);
}
#tool-body .confirm-dialog .confirm-actions .btn-confirm.primary:hover {
  background: var(--primary-dark);
}

/* ========== 響應式 ========== */
@media (max-width: 520px) {
  #tool-body .math-card {
    padding: 16px 12px;
  }
  #tool-body .config-title {
    font-size: 22px;
  }
  #tool-body .problem-expr {
    font-size: 36px;
  }
  #tool-body .answer-display {
    font-size: 32px;
    min-height: 40px;
    min-width: 60px;
  }
  #tool-body .numpad-key {
    font-size: 22px;
    padding: 12px 0;
  }
  #tool-body .numpad {
    gap: 8px;
  }
  #tool-body .play-header {
    font-size: 13px;
  }
  #tool-body .feedback {
    font-size: 17px;
  }
  #tool-body .summary-grid {
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }
  #tool-body .summary-item .num {
    font-size: 26px;
  }
  #tool-body .modal-content {
    padding: 18px 16px;
  }
  #tool-body .range-custom input {
    width: 52px;
  }
  #tool-body .op-btn {
    padding: 6px 14px;
    font-size: 14px;
    min-width: 50px;
  }
}
@media (max-width: 400px) {
  #tool-body .problem-expr {
    font-size: 30px;
  }
  #tool-body .answer-display {
    /*     font-size: 26px; */
    min-height: 34px;
    min-width: 50px;
  }
  #tool-body .numpad-key {
    font-size: 18px;
    padding: 10px 0;
  }
  #tool-body .play-header {
    font-size: 12px;
    /*     flex-direction: column; */
    align-items: stretch;
    gap: 4px;
  }
  #tool-body .play-header .stats {
    justify-content: center;
  }
}

/* ========== 工具類 ========== */
#tool-body .text-center {
  text-align: center;
}
#tool-body .mt-8 {
  margin-top: 8px;
}
#tool-body .mb-4 {
  margin-bottom: 4px;
}
#tool-body .flex-wrap {
  display: flex;
  flex-wrap: wrap;
}
#tool-body .items-center {
  align-items: center;
}
#tool-body .justify-center {
  justify-content: center;
}
#tool-body .gap-4 {
  gap: 4px;
}
@keyframes toastFadeIn {
  from {
    opacity: 0;
    transform: translateX(-50%) scale(0.9);
  }
  to {
    opacity: 1;
    transform: translateX(-50%) scale(1);
  }
}
/* Toast 提示 */
#tool-body .toast-float {
  position: fixed;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--card-bg);
  color: inherit;
  padding: 12px 28px;
  border-radius: 16px;
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.18);
  font-size: 16px;
  font-family: inherit;
  z-index: 99999;
  border-left: 5px solid var(--primary);
  max-width: 90%;
  text-align: center;
  animation: toastFadeIn 0.25s ease;
}
#tool-body .range-hint {
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 6px;
  padding-left: 2px;
  opacity: 0.8;
}