/* ===== 全局重置 ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --primary: #4f46e5;
  --primary-light: #818cf8;
  --primary-dark: #3730a3;
  --success: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --bg: #f1f5f9;
  --bg-card: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --shadow: 0 4px 20px rgba(0,0,0,0.08);
  --radius: 14px;
  --radius-sm: 8px;
}

body {
  font-family: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

/* ===== 顶部标题 ===== */
.header {
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 60%, var(--primary-light) 100%);
  color: white;
  padding: 28px 20px 24px;
  text-align: center;
  box-shadow: 0 4px 16px rgba(79,70,229,0.3);
}

.header h1 {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: 1px;
}

.subtitle {
  margin-top: 6px;
  font-size: 0.95rem;
  opacity: 0.85;
}

/* ===== 主容器 ===== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 16px 60px;
}

/* ===== 统计栏 ===== */
.stats-bar {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 24px;
}

.stat-item {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 16px 28px;
  text-align: center;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  min-width: 110px;
}

.stat-num {
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary);
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 600;
}

/* 进度圆圈 */
.progress-circle {
  position: relative;
  width: 52px;
  height: 52px;
}

.progress-circle svg {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.circle-bg {
  fill: none;
  stroke: var(--border);
  stroke-width: 3.5;
}

.circle-fill {
  fill: none;
  stroke: var(--primary);
  stroke-width: 3.5;
  stroke-linecap: round;
  transition: stroke-dasharray 0.5s ease;
}

.circle-text {
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  font-size: 0.65rem;
  font-weight: 800;
  color: var(--primary);
}

/* ===== 工具栏 ===== */
.toolbar {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 24px;
}

.search-box input {
  width: 100%;
  padding: 12px 18px;
  border-radius: 50px;
  border: 2px solid var(--border);
  font-size: 1rem;
  outline: none;
  background: var(--bg-card);
  transition: border-color 0.2s;
  box-shadow: var(--shadow);
}

.search-box input:focus {
  border-color: var(--primary);
}

/* 字母筛选 */
.filter-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-btn {
  padding: 6px 14px;
  border-radius: 50px;
  border: 2px solid var(--border);
  background: var(--bg-card);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s;
}

.filter-btn:hover {
  border-color: var(--primary-light);
  color: var(--primary);
}

.filter-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
}

/* 模式切换 */
.mode-group {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.mode-btn {
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--border);
  background: var(--bg-card);
  color: var(--text-muted);
  font-weight: 700;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s;
}

.mode-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.mode-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
}

/* ===== 列表模式 ===== */
.word-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}

.word-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 18px 20px;
  box-shadow: var(--shadow);
  cursor: pointer;
  border: 2px solid transparent;
  transition: all 0.2s;
  position: relative;
}

.word-card:hover {
  border-color: var(--primary-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(79,70,229,0.15);
}

.word-card.known {
  border-color: var(--success);
  background: #f0fdf4;
}

.word-card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
}

.word-en {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--primary-dark);
}

.word-phonetic {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 4px;
  font-style: italic;
}

.word-pos {
  font-size: 0.75rem;
  background: var(--primary-light);
  color: white;
  border-radius: 50px;
  padding: 2px 10px;
  font-weight: 700;
  white-space: nowrap;
}

.word-cn {
  margin-top: 10px;
  font-size: 0.95rem;
  color: var(--text);
  line-height: 1.5;
}

.word-phrase {
  margin-top: 8px;
  font-size: 0.82rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  padding-top: 8px;
}

.known-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  font-size: 1.1rem;
}

/* ===== 卡片模式 ===== */
.card-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.flashcard {
  width: 100%;
  max-width: 520px;
  height: 320px;
  perspective: 1000px;
  cursor: pointer;
}

.card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 0.5s ease;
}

.card-inner.flipped {
  transform: rotateY(180deg);
}

.card-front, .card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 36px;
  box-shadow: var(--shadow);
  text-align: center;
}

.card-front {
  background: linear-gradient(135deg, #ede9fe, #ddd6fe);
  border: 2px solid var(--primary-light);
}

.card-back {
  background: linear-gradient(135deg, #ecfdf5, #d1fae5);
  border: 2px solid var(--success);
  transform: rotateY(180deg);
}

.card-word {
  font-size: 2.4rem;
  font-weight: 900;
  color: var(--primary-dark);
}

.card-phonetic {
  font-size: 1rem;
  color: var(--text-muted);
  margin-top: 8px;
  font-style: italic;
}

.card-hint {
  margin-top: 20px;
  font-size: 0.85rem;
  color: var(--primary);
  opacity: 0.7;
}

.card-pos {
  font-size: 0.9rem;
  background: var(--success);
  color: white;
  border-radius: 50px;
  padding: 4px 16px;
  font-weight: 700;
  margin-bottom: 12px;
}

.card-meaning {
  font-size: 1.3rem;
  font-weight: 700;
  color: #065f46;
  line-height: 1.5;
}

.card-phrase {
  margin-top: 10px;
  font-size: 0.85rem;
  color: #047857;
}

.card-controls {
  display: flex;
  align-items: center;
  gap: 20px;
}

.card-counter {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-muted);
}

.ctrl-btn {
  padding: 10px 22px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--primary);
  background: white;
  color: var(--primary);
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all 0.2s;
}

.ctrl-btn:hover {
  background: var(--primary);
  color: white;
}

.card-actions {
  display: flex;
  gap: 14px;
}

.action-btn {
  padding: 10px 26px;
  border-radius: var(--radius-sm);
  border: none;
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-known {
  background: var(--success);
  color: white;
}

.btn-known:hover {
  background: #059669;
}

.btn-unknown {
  background: var(--danger);
  color: white;
}

.btn-unknown:hover {
  background: #dc2626;
}

/* ===== 测试模式 ===== */
.quiz-wrapper {
  max-width: 640px;
  margin: 0 auto;
}

.quiz-info {
  display: flex;
  justify-content: space-between;
  margin-bottom: 20px;
  font-weight: 700;
  color: var(--text-muted);
}

.quiz-question {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 32px;
  text-align: center;
  box-shadow: var(--shadow);
  margin-bottom: 20px;
}

.quiz-word {
  font-size: 2.2rem;
  font-weight: 900;
  color: var(--primary-dark);
}

.quiz-phonetic {
  font-size: 0.95rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 6px;
}

.quiz-ask {
  margin-top: 14px;
  font-size: 0.95rem;
  color: var(--text-muted);
}

.quiz-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 16px;
}

.quiz-option {
  padding: 16px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--border);
  background: var(--bg-card);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-align: center;
  transition: all 0.2s;
  box-shadow: var(--shadow);
}

.quiz-option:hover:not(.disabled) {
  border-color: var(--primary);
  color: var(--primary);
}

.quiz-option.correct {
  background: #f0fdf4;
  border-color: var(--success);
  color: var(--success);
}

.quiz-option.wrong {
  background: #fef2f2;
  border-color: var(--danger);
  color: var(--danger);
}

.quiz-option.disabled {
  cursor: not-allowed;
  opacity: 0.7;
}

.quiz-result {
  text-align: center;
  padding: 12px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 12px;
}

.quiz-result.correct-msg {
  background: #f0fdf4;
  color: var(--success);
}

.quiz-result.wrong-msg {
  background: #fef2f2;
  color: var(--danger);
}

.quiz-next {
  display: block;
  width: 100%;
  padding: 14px;
  border-radius: var(--radius-sm);
  border: none;
  background: var(--primary);
  color: white;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  margin-bottom: 16px;
  transition: background 0.2s;
}

.quiz-next:hover {
  background: var(--primary-dark);
}

.quiz-finish {
  text-align: center;
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 40px;
  box-shadow: var(--shadow);
}

.quiz-finish h2 {
  font-size: 1.8rem;
  margin-bottom: 12px;
}

.quiz-finish p {
  font-size: 1.1rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

/* ===== 弹窗 ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 16px;
  backdrop-filter: blur(3px);
}

.modal {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 36px;
  max-width: 480px;
  width: 100%;
  position: relative;
  box-shadow: 0 20px 60px rgba(0,0,0,0.2);
  animation: modalIn 0.25s ease;
}

@keyframes modalIn {
  from { transform: scale(0.9); opacity: 0; }
  to   { transform: scale(1);   opacity: 1; }
}

.modal-close {
  position: absolute;
  top: 14px; right: 16px;
  background: none;
  border: none;
  font-size: 1.3rem;
  cursor: pointer;
  color: var(--text-muted);
}

.modal-word {
  font-size: 2rem;
  font-weight: 900;
  color: var(--primary-dark);
}

.modal-phonetic {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 4px;
}

.modal-pos {
  display: inline-block;
  margin: 12px 0 6px;
  font-size: 0.8rem;
  background: var(--primary);
  color: white;
  border-radius: 50px;
  padding: 3px 14px;
  font-weight: 700;
}

.modal-meaning {
  font-size: 1.1rem;
  line-height: 1.6;
  color: var(--text);
  margin-bottom: 14px;
}

.modal-phrase-title {
  font-size: 0.85rem;
  font-weight: 800;
  color: var(--text-muted);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.modal-phrase {
  font-size: 0.92rem;
  color: var(--text);
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  line-height: 1.7;
  margin-bottom: 20px;
}

.modal-footer {
  display: flex;
  justify-content: center;
}

/* ===== 工具类 ===== */
.hidden {
  display: none !important;
}

/* ===== 响应式 ===== */
@media (max-width: 600px) {
  .header h1 { font-size: 1.4rem; }
  .word-grid { grid-template-columns: 1fr; }
  .quiz-options { grid-template-columns: 1fr; }
  .stats-bar { gap: 10px; }
  .stat-item { padding: 12px 18px; min-width: 80px; }
  .card-word { font-size: 1.8rem; }
  .quiz-word { font-size: 1.6rem; }
}