/* Reset and base styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Colors - 21st.dev inspired dark theme */
  --bg-primary: #0a0a0a;
  --bg-secondary: #141414;
  --bg-tertiary: #1a1a1a;
  --border-color: #2a2a2a;
  --border-hover: #3a3a3a;

  --text-primary: #ffffff;
  --text-secondary: #a0a0a0;
  --text-tertiary: #707070;

  --accent-primary: #0066ff;
  --accent-hover: #0052cc;
  --accent-light: rgba(0, 102, 255, 0.1);

  --success: #00d084;
  --error: #ff4444;
  --warning: #ffaa00;

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;

  /* Border radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  /* Transitions */
  --transition: all 0.2s ease;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Helvetica Neue", Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-md);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md) 0;
  margin-bottom: var(--spacing-lg);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
}

.logo svg {
  color: var(--accent-primary);
}

/* Ensure image logo displays cleanly */
.logo img,
.logo .logo-image {
  height: 48px; /* +20% from 40px */
  width: auto;
  display: block;
  object-fit: contain;
}

.btn-back {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-xs) var(--spacing-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition);
}

.btn-back:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-hover);
  color: var(--text-primary);
}

/* Main content */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}

/* Hero section */
.hero {
  margin-bottom: var(--spacing-xl);
}

.title {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
}

/* Steps container */
.steps-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
  width: 100%;
  max-width: 900px;
}

.step-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: var(--transition);
}

.step-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

.step-icon {
  width: 48px;
  height: 48px;
  margin: 0 auto var(--spacing-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-light);
  border-radius: var(--radius-md);
  color: var(--accent-primary);
}

.step-number {
  display: inline-block;
  padding: 4px 12px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-sm);
}

.step-card h3 {
  font-size: 1.125rem;
  margin-bottom: var(--spacing-xs);
  color: var(--text-primary);
}

.step-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* CTA */
.cta-container {
  /* Center CTAs and give breathing room above and below */
  margin: var(--spacing-lg) 0 var(--spacing-xl);
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-md) var(--spacing-xl);
  background: var(--accent-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1.125rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 102, 255, 0.3);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-md) var(--spacing-lg);
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.btn-secondary:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-hover);
}

/* Button corner badge for counts */
.btn-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.25rem;
  height: 1.25rem;
  padding: 0 6px;
  margin-left: 8px;
  background: var(--error);
  color: #fff;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  line-height: 1;
}

/* Footer */
.footer {
  text-align: center;
  padding: var(--spacing-lg) 0;
  color: var(--text-tertiary);
  font-size: 0.875rem;
  border-top: 1px solid var(--border-color);
  margin-top: var(--spacing-xl);
}

/* Page header */
.page-header {
  margin-bottom: var(--spacing-xl);
}

.page-header h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: var(--spacing-xs);
}

.page-header p {
  font-size: 1.125rem;
  color: var(--text-secondary);
}

/* Grade grid */
.grade-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--spacing-md);
  width: 100%;
  max-width: 800px;
  margin-top: var(--spacing-lg);
}

.grade-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl) var(--spacing-lg);
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
}

.grade-card:hover {
  border-color: var(--accent-primary);
  background: var(--accent-light);
  transform: translateY(-4px);
}

.grade-number {
  font-size: 3rem;
  font-weight: 700;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-xs);
}

.grade-label {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.grade-info {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* Semester grid */
.semester-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
  width: 100%;
  max-width: 700px;
}

.semester-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
}

.semester-card:hover {
  border-color: var(--accent-primary);
  background: var(--accent-light);
  transform: translateY(-4px);
}

.semester-icon {
  margin-bottom: var(--spacing-md);
  color: var(--accent-primary);
}

.semester-card h2 {
  font-size: 1.5rem;
  margin-bottom: var(--spacing-xs);
}

.semester-card p {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-md);
}

.semester-units {
  display: inline-block;
  padding: 6px 16px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  color: var(--accent-primary);
}

/* Unit grid */
.unit-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--spacing-md);
  width: 100%;
  max-width: 900px;
}

.unit-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: var(--spacing-lg);
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
}

.unit-card:hover {
  border-color: var(--accent-primary);
  background: var(--accent-light);
  transform: translateY(-2px);
}

.unit-number {
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-xs);
}

.unit-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xs);
}

.unit-words {
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

/* Practice page */
.practice-content {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-lg) 0;
}

.practice-card {
  width: 100%;
  max-width: 600px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  text-align: center;
}

.progress-info {
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.progress-bar-container {
  width: 100%;
  height: 4px;
  background: var(--bg-tertiary);
  border-radius: 2px;
  margin-bottom: var(--spacing-xl);
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  background: var(--accent-primary);
  transition: width 0.3s ease;
}

.phonetic-display {
  font-size: 1.25rem;
  font-family: 'Courier New', 'Consolas', monospace;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-sm);
  font-weight: 500;
  letter-spacing: 1px;
  text-align: center;
}

.chinese-meaning {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xl);
  min-height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.audio-control {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xl);
}

.btn-audio {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-lg);
  background: var(--accent-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-audio:hover {
  background: var(--accent-hover);
  transform: scale(1.05);
}

.btn-audio:active {
  transform: scale(0.98);
}

.btn-slow {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
}

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

.btn-slow.active {
  background: var(--accent-light);
  border-color: var(--accent-primary);
  color: var(--accent-primary);
}

/* Input container with underline style */
.input-container {
  position: relative;
  margin-bottom: var(--spacing-md);
}

.word-input {
  width: 100%;
  padding: var(--spacing-md) 0;
  background: transparent;
  border: none;
  border-bottom: 2px solid var(--border-color);
  color: var(--text-primary);
  font-size: 1.5rem;
  font-weight: 500;
  text-align: center;
  outline: none;
  transition: var(--transition);
}

.word-input::placeholder {
  color: var(--text-tertiary);
  font-size: 1rem;
}

.word-input:focus {
  border-bottom-color: var(--accent-primary);
}

.input-underline {
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%) scaleX(0);
  width: 100%;
  height: 2px;
  background: var(--accent-primary);
  transition: transform 0.3s ease;
}

.word-input:focus + .input-underline {
  transform: translateX(-50%) scaleX(1);
}

.peek-hint {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-bottom: var(--spacing-md);
}

.answer-display {
  display: none;
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--accent-primary);
  padding: var(--spacing-md);
  background: var(--accent-light);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-md);
  animation: fadeIn 0.2s ease;
}

.answer-display.show {
  display: block;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.feedback-message {
  min-height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.125rem;
  font-weight: 500;
  margin-bottom: var(--spacing-md);
}

.feedback-message.correct {
  color: var(--success);
}

.feedback-message.wrong {
  color: var(--error);
}

.action-buttons {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: center;
  margin-bottom: var(--spacing-md);
}

.streak-counter {
  font-size: 1rem;
  color: var(--text-secondary);
  padding: var(--spacing-sm);
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
}

#streakNumber {
  color: var(--accent-primary);
  font-weight: 700;
}

/* Results page */
.results-content {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-lg) 0;
}

.results-card {
  width: 100%;
  max-width: 700px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  text-align: center;
}

.results-title {
  font-size: 2rem;
  margin-bottom: var(--spacing-xl);
}

.score-badge {
  margin-bottom: var(--spacing-xl);
}

.badge-icon {
  font-size: 4rem;
  margin-bottom: var(--spacing-sm);
}

.score-percentage {
  font-size: 3.5rem;
  font-weight: 700;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-xs);
}

.score-label {
  font-size: 1.125rem;
  color: var(--text-secondary);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}

.stat-item {
  padding: var(--spacing-md);
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-primary);
  margin-bottom: var(--spacing-xs);
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.wrong-words-section {
  margin-bottom: var(--spacing-xl);
  text-align: left;
}

.wrong-words-section h2 {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-md);
  text-align: center;
}

.wrong-words-list {
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  max-height: 300px;
  overflow-y: auto;
}

.wrong-word-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-sm);
  border-bottom: 1px solid var(--border-color);
}

.wrong-word-item:last-child {
  border-bottom: none;
}

.wrong-word-en {
  font-weight: 600;
  color: var(--text-primary);
}

.wrong-word-cn {
  color: var(--text-secondary);
}

.results-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  justify-content: center;
}

/* Responsive */
@media (max-width: 768px) {
  .title {
    font-size: 2rem;
  }

  .subtitle {
    font-size: 1rem;
  }

  .steps-container {
    grid-template-columns: 1fr;
  }

  .grade-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .semester-grid {
    grid-template-columns: 1fr;
  }

  .unit-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .chinese-meaning {
    font-size: 2rem;
  }

  .word-input {
    font-size: 1.25rem;
  }

  .results-actions {
    flex-direction: column;
  }

  .results-actions button {
    width: 100%;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .container {
    padding: var(--spacing-sm);
  }

  .title {
    font-size: 1.5rem;
  }

  .page-header h1 {
    font-size: 1.75rem;
  }

  .unit-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .practice-card {
    padding: var(--spacing-lg);
  }

  .action-buttons {
    flex-direction: column;
  }

  .action-buttons button {
    width: 100%;
  }
}

/* ==================== 炫酷二次元科技背景 ==================== */

/* 主容器 */
.anime-tech-background {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  overflow: hidden;
  background: linear-gradient(
    135deg,
    #0a0a0f 0%,
    #1a0a2e 25%,
    #0f051d 50%,
    #1a0a2e 75%,
    #0a0a0f 100%
  );
  background-size: 400% 400%;
  animation: cyber-gradient 15s ease infinite;
}

@keyframes cyber-gradient {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

/* 科技网格 */
.tech-grid {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: 
    linear-gradient(rgba(138, 43, 226, 0.1) 1px, transparent 1px),
    linear-gradient(90deg, rgba(138, 43, 226, 0.1) 1px, transparent 1px);
  background-size: 50px 50px;
  animation: grid-move 20s linear infinite;
}

@keyframes grid-move {
  0% { transform: translateY(0); }
  100% { transform: translateY(50px); }
}

/* 粒子层 */
.particle-layer {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.particle {
  position: absolute;
  background: #00f5ff;
  border-radius: 50%;
  box-shadow: 0 0 10px #00f5ff, 0 0 20px #00f5ff;
  animation: particle-float 4s ease-in-out infinite;
}

@keyframes particle-float {
  0%, 100% {
    transform: translateY(0) translateX(0);
    opacity: 0.3;
  }
  50% {
    transform: translateY(-20px) translateX(10px);
    opacity: 1;
  }
}

/* 扫描线 */
.scan-line {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(0, 245, 255, 0.8),
    transparent
  );
  box-shadow: 0 0 20px rgba(0, 245, 255, 0.8);
  animation: scan 8s linear infinite;
}

@keyframes scan {
  0% { transform: translateY(0); }
  100% { transform: translateY(100vh); }
}

/* 漂浮单词 - 向上移动 */
.floating-word {
  position: absolute;
  font-family: 'Courier New', 'Consolas', monospace;
  font-weight: bold;
  font-size: 24px;
  letter-spacing: 2px;
  pointer-events: none;
  white-space: nowrap;
  animation: float-up-glow 10s ease-out forwards;
  z-index: 1;
}

@keyframes float-up-glow {
  0% {
    transform: translateY(0) translateX(0) scale(1);
    opacity: 0;
  }
  10% {
    opacity: 1;
  }
  50% {
    transform: translateY(-50vh) translateX(20px) scale(1.2);
    opacity: 0.9;
  }
  90% {
    opacity: 0.5;
  }
  100% {
    transform: translateY(-120vh) translateX(-20px) scale(0.8);
    opacity: 0;
  }
}

/* 代码雨层 */
.code-rain-layer {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 0;
}

/* 代码雨 */
.code-rain {
  position: absolute;
  top: -100%;
  font-family: 'Courier New', 'Consolas', monospace;
  font-size: 14px;
  font-weight: bold;
  line-height: 1.5;
  white-space: pre;
  opacity: 0.6;
  animation: code-fall 8s linear forwards;
  letter-spacing: 1px;
}

@keyframes code-fall {
  0% {
    transform: translateY(0);
    opacity: 0;
  }
  10% {
    opacity: 0.8;
  }
  90% {
    opacity: 0.4;
  }
  100% {
    transform: translateY(120vh);
    opacity: 0;
  }
}

/* 霓虹发光效果增强 */
.floating-word:nth-child(2n) {
  animation: float-up-glow 12s ease-out forwards, pulse-glow 2s ease-in-out infinite;
}

.floating-word:nth-child(3n) {
  animation: float-up-glow 9s ease-out forwards, rotate-glow 15s linear infinite;
}

@keyframes pulse-glow {
  0%, 100% {
    filter: brightness(1);
  }
  50% {
    filter: brightness(1.5);
  }
}

@keyframes rotate-glow {
  0% {
    filter: hue-rotate(0deg);
  }
  100% {
    filter: hue-rotate(360deg);
  }
}

/* 添加毛玻璃效果到内容容器 */
.container {
  background: rgba(10, 10, 15, 0.3);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(138, 43, 226, 0.3);
  box-shadow: 
    0 8px 32px rgba(0, 0, 0, 0.3),
    inset 0 0 20px rgba(138, 43, 226, 0.15);
}

/* 响应式优化 */
@media (max-width: 768px) {
  .floating-word {
    font-size: 18px;
  }
  
  .code-rain {
    font-size: 12px;
  }
  
  .tech-grid {
    background-size: 30px 30px;
  }
}

/* 性能优化 - 降低复杂度 */
@media (prefers-reduced-motion: reduce) {
  .anime-tech-background,
  .floating-word,
  .code-rain,
  .scan-line {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}

/* ==================== 小学总复习样式 ==================== */

.cta-container {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 2rem;
}

.btn-secondary {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.875rem 1.75rem;
  background: linear-gradient(135deg, var(--accent-primary), #00ccff);
  border: 1px solid rgba(0, 102, 255, 0.3);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 15px rgba(0, 102, 255, 0.2);
}

.btn-secondary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 102, 255, 0.35);
  background: linear-gradient(135deg, #0052cc, #00aadd);
}

.btn-secondary:active {
  transform: translateY(0);
}

/* 进度条 */
.progress-container {
  margin-bottom: 1.5rem;
}

.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--bg-secondary);
  border-radius: 4px;
  overflow: hidden;
  border: 1px solid var(--border-color);
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-primary), #00d084);
  transition: width 0.3s ease;
  box-shadow: 0 0 10px rgba(0, 102, 255, 0.5);
}

.progress-text {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 0.5rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* 页面标题 */
.page-title {
  font-size: 2rem;
  text-align: center;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

/* 完成界面 */
.completion-screen {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 600px;
  padding: 3rem;
}

.completion-content {
  text-align: center;
  max-width: 500px;
}

.completion-icon {
  font-size: 5rem;
  margin-bottom: 1rem;
  animation: bounce 1s ease-in-out infinite;
}

@keyframes bounce {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-10px);
  }
}

.completion-content h2 {
  font-size: 2rem;
  margin-bottom: 1rem;
  color: var(--success);
}

.completion-content p {
  color: var(--text-secondary);
  margin-bottom: 2rem;
  font-size: 1.1rem;
}

/* 最终统计 */
.final-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-bottom: 2rem;
  background: var(--bg-secondary);
  padding: 1.5rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.final-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.final-stat .label {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.final-stat .value {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--accent-primary);
}

.final-stat .value.correct-stat {
  color: var(--success);
}

.final-stat .value.error-stat {
  color: var(--error);
}

/* 错词列表 */
.wrong-words-section {
  margin-top: 2rem;
  text-align: left;
}

.wrong-words-section h3 {
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.wrong-words-list {
  max-height: 300px;
  overflow-y: auto;
}

.wrong-word-item {
  background: var(--bg-secondary);
  border-left: 3px solid var(--error);
  padding: 1rem;
  margin-bottom: 0.75rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.wrong-word-header {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.5rem;
}

.word-english {
  font-weight: 600;
  color: var(--accent-primary);
}

.word-chinese {
  color: var(--text-secondary);
}

.wrong-word-answer {
  font-size: 0.9rem;
  color: var(--text-tertiary);
  margin-bottom: 0.25rem;
}

.user-answer {
  color: var(--error);
  font-weight: 600;
}

.wrong-word-source {
  font-size: 0.85rem;
  color: var(--text-tertiary);
  margin-top: 0.5rem;
}

/* 统计信息容器 */
.stats-container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-top: 2rem;
}

.stat-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 1.5rem;
  border-radius: var(--radius-md);
  text-align: center;
  transition: var(--transition);
}

.stat-card:hover {
  border-color: var(--border-hover);
  background: var(--bg-tertiary);
}

.stat-card.correct {
  border-left: 3px solid var(--success);
}

.stat-card.incorrect {
  border-left: 3px solid var(--error);
}

.stat-card.accuracy {
  border-left: 3px solid var(--accent-primary);
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.stat-card.correct .stat-value {
  color: var(--success);
}

.stat-card.incorrect .stat-value {
  color: var(--error);
}

.stat-card.accuracy .stat-value {
  color: var(--accent-primary);
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* 响应式设计 */
@media (max-width: 768px) {
  .cta-container {
    flex-direction: column;
    margin: var(--spacing-md) 0 var(--spacing-lg);
  }

  .btn-primary,
  .btn-secondary {
    width: 100%;
  }

  .completion-screen {
    padding: 1.5rem;
    min-height: auto;
  }

  .final-stats {
    grid-template-columns: repeat(2, 1fr);
  }

  .stats-container {
    grid-template-columns: 1fr;
  }

  .page-title {
    font-size: 1.5rem;
  }

  .completion-icon {
    font-size: 3rem;
  }

  .completion-content h2 {
    font-size: 1.5rem;
  }
}

/* ==================== 错词本样式 ==================== */

.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 500px;
  text-align: center;
}

.empty-icon {
  font-size: 4rem;
  margin-bottom: 1rem;
}

.empty-state h2 {
  font-size: 1.5rem;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.empty-state p {
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.empty-message {
  padding: 2rem;
  text-align: center;
  color: var(--text-secondary);
  background: rgba(0, 102, 255, 0.05);
  border: 1px dashed rgba(0, 102, 255, 0.2);
  border-radius: var(--radius-md);
}

/* Mistake book layout */
.mistake-book-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  padding: var(--spacing-lg) 0;
}

.mistake-book-header {
  text-align: center;
  margin-bottom: var(--spacing-lg);
}

.mistake-book-header h1 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
}

.stat-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.25rem 0.75rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 999px;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.mistake-list-container {
  width: 100%;
  max-width: 760px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: var(--spacing-lg);
  margin: 0 auto;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}

.mistake-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.mistake-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-md);
  padding: var(--spacing-md);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  transition: var(--transition);
}

.mistake-item:hover {
  border-color: var(--accent-primary);
  transform: translateY(-2px);
}

.mistake-item-content {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 6px;
  min-width: 0;
}

.mistake-item-word {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.mistake-item-en {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
}

.mistake-item-phonetic {
  font-size: 0.95rem;
  color: var(--accent-primary);
  font-family: 'Courier New', 'Consolas', monospace;
}

.mistake-item-meaning {
  color: var(--text-secondary);
}

.mistake-item-actions {
  display: flex;
  flex-shrink: 0;
  gap: var(--spacing-sm);
}

.btn-small {
  width: 40px;
  height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  border: 1px solid var(--border-color);
  background: var(--bg-primary);
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
}

.btn-small:hover {  
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: rgba(0, 102, 255, 0.06);
}

.btn-small svg {
  width: 18px;
  height: 18px;
}

.btn-small.btn-remove:hover {
  border-color: var(--error);
  color: var(--error);
  background: rgba(255, 68, 68, 0.08);
}

.mistake-book-actions {
  display: flex;
  justify-content: center;
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

.mistake-book-actions .btn-primary,
.mistake-book-actions .btn-secondary {
  min-width: 220px;
  padding: var(--spacing-md) var(--spacing-xl);
}

@media (max-width: 768px) {
  .mistake-list-container {
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
  }
  .mistake-book-actions {
    flex-direction: column;
  }
  .mistake-book-actions .btn-primary,
  .mistake-book-actions .btn-secondary {
    width: 100%;
    min-width: 0;
  }
}

/* 错题统计 */
.error-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin: 2rem 0;
}

.error-stats .stat-card {
  border-left: 3px solid var(--error);
}

.error-stats .stat-value {
  color: var(--error);
}

/* 筛选按钮 */
.filter-section {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin: 2rem 0;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 0.75rem 1.5rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 50px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition);
}

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

.filter-btn.active {
  background: var(--accent-primary);
  border-color: var(--accent-primary);
  color: var(--text-primary);
  box-shadow: 0 4px 12px rgba(0, 102, 255, 0.3);
}

/* 错题列表 */
.error-list {
  margin: 2rem 0;
}

.error-item {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-left: 3px solid var(--error);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  margin-bottom: 1rem;
  transition: var(--transition);
}

.error-item:hover {
  border-color: var(--accent-primary);
  box-shadow: 0 6px 16px rgba(0, 102, 255, 0.1);
}

.error-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.error-index {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: rgba(255, 68, 68, 0.2);
  border-radius: 50%;
  color: var(--error);
  font-weight: 600;
  font-size: 0.9rem;
}

.error-word {
  flex: 1;
  display: flex;
  gap: 1rem;
  align-items: center;
}

.word-english {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--accent-primary);
}

.word-chinese {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.error-mode {
  margin-left: auto;
}

.mode-badge {
  padding: 0.25rem 0.75rem;
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 600;
}

.mode-normal {
  background: rgba(0, 102, 255, 0.15);
  color: var(--accent-primary);
}

.mode-review {
  background: rgba(0, 208, 132, 0.15);
  color: var(--success);
}

/* 错题详情 */
.error-details {
  background: rgba(0, 0, 0, 0.2);
  padding: 1rem;
  border-radius: var(--radius-sm);
  margin-bottom: 1rem;
}

.detail-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border-color);
}

.detail-row:last-child {
  border-bottom: none;
}

.detail-label {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.detail-value {
  font-weight: 500;
  color: var(--text-primary);
}

.detail-value.correct {
  color: var(--success);
}

.detail-value.user-answer {
  color: var(--error);
}

.detail-value.source {
  color: var(--text-secondary);
  font-size: 0.85rem;
}

.detail-value.time {
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

/* 错题操作按钮 */
.error-actions {
  display: flex;
  gap: 1rem;
  justify-content: flex-end;
}

.btn-retry,
.btn-delete {
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  border: 1px solid;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-retry {
  background: rgba(0, 208, 132, 0.1);
  border-color: rgba(0, 208, 132, 0.3);
  color: var(--success);
}

.btn-retry:hover {
  background: rgba(0, 208, 132, 0.2);
  border-color: var(--success);
}

.btn-delete {
  background: rgba(255, 68, 68, 0.1);
  border-color: rgba(255, 68, 68, 0.3);
  color: var(--error);
}

.btn-delete:hover {
  background: rgba(255, 68, 68, 0.2);
  border-color: var(--error);
}

/* 批量操作 */
.batch-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-top: 3rem;
  flex-wrap: wrap;
}

/* 动画 */
@keyframes slideOut {
  to {
    opacity: 0;
    transform: translateX(20px);
  }
}

.btn-tertiary {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.875rem 1.75rem;
  background: linear-gradient(135deg, #ff6b6b, #ff4757);
  border: 1px solid rgba(255, 71, 87, 0.3);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 15px rgba(255, 71, 87, 0.2);
}

.btn-tertiary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(255, 71, 87, 0.35);
  background: linear-gradient(135deg, #ff5252, #ff3838);
}

.btn-tertiary:active {
  transform: translateY(0);
}

/* ==================== 输入框和按钮样式 ==================== */

.input-section {
  display: flex;
  gap: 1rem;
  margin: 1.5rem 0;
}

.answer-input {
  flex: 1;
  padding: 0.75rem 0.5rem;
  background: transparent;
  border: none;
  border-bottom: 2px solid var(--border-color);
  border-radius: 0;
  color: var(--text-primary);
  font-size: 1rem;
  transition: var(--transition);
}

.answer-input:focus {
  outline: none;
  border-bottom-color: var(--accent-primary);
  box-shadow: 0 2px 8px rgba(0, 102, 255, 0.2);
}

.answer-input::placeholder {
  color: var(--text-tertiary);
}

.btn-submit {
  padding: 1rem 1.5rem;
  background: linear-gradient(135deg, var(--accent-primary), #0052cc);
  border: 1px solid rgba(0, 102, 255, 0.3);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 12px rgba(0, 102, 255, 0.2);
}

.btn-submit:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(0, 102, 255, 0.35);
  background: linear-gradient(135deg, #0052cc, #003d99);
}

.btn-submit:active {
  transform: translateY(0);
}

/* 控制按钮 */
.btn-control {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 50px;
  height: 50px;
  background: var(--bg-secondary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--accent-primary);
  cursor: pointer;
  transition: var(--transition);
  font-size: 0;
}

.btn-control svg {
  width: 24px;
  height: 24px;
  stroke: currentColor;
}

.btn-control:hover {
  border-color: var(--accent-primary);
  background: rgba(0, 102, 255, 0.1);
  box-shadow: 0 0 12px rgba(0, 102, 255, 0.2);
}

.btn-control:active {
  transform: scale(0.95);
}

.btn-control.active {
  border-color: var(--success);
  color: var(--success);
  box-shadow: 0 0 12px rgba(0, 208, 132, 0.3);
}

/* 大播放按钮 */
.btn-play-large {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 2rem;
  margin: 1.5rem auto;
  background: linear-gradient(135deg, var(--accent-primary), #0052cc);
  border: 1px solid rgba(0, 102, 255, 0.3);
  border-radius: 50px;
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 6px 20px rgba(0, 102, 255, 0.3);
}

.btn-play-large:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 102, 255, 0.4);
  background: linear-gradient(135deg, #0052cc, #003d99);
}

.btn-play-large:active {
  transform: translateY(0);
}

.btn-play-large svg {
  width: 24px;
  height: 24px;
}

/* 小慢速按钮 */
.btn-slow-compact {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 45px;
  height: 45px;
  margin-left: -1rem;
  background: var(--bg-secondary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
}

.btn-slow-compact:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  box-shadow: 0 0 12px rgba(0, 102, 255, 0.2);
}

.btn-slow-compact.active {
  border-color: var(--success);
  color: var(--success);
  box-shadow: 0 0 12px rgba(0, 208, 132, 0.3);
}

/* 动作按钮组 */
.action-buttons {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin: 2rem 0 1.5rem 0;
}

.btn-skip {
  padding: 0.875rem 1.75rem;
  background: rgba(0, 102, 255, 0.2);
  border: 1px solid rgba(0, 102, 255, 0.4);
  border-radius: 50px;
  color: var(--accent-primary);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 12px rgba(0, 102, 255, 0.1);
}

.btn-skip:hover {
  background: rgba(0, 102, 255, 0.3);
  border-color: rgba(0, 102, 255, 0.6);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(0, 102, 255, 0.2);
}

.btn-skip:active {
  transform: translateY(0);
}

/* 按钮组 */
.button-group {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin: 1.5rem 0;
  flex-wrap: wrap;
}

/* 反馈消息 */
.feedback-message {
  margin-top: 1rem;
  padding: 1rem;
  border-radius: var(--radius-md);
  text-align: center;
  font-weight: 600;
  transition: var(--transition);
  min-height: 45px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.feedback-message.correct {
  background: rgba(0, 208, 132, 0.15);
  color: var(--success);
  border: 1px solid rgba(0, 208, 132, 0.3);
}

.feedback-message.incorrect {
  background: rgba(255, 68, 68, 0.15);
  color: var(--error);
  border: 1px solid rgba(255, 68, 68, 0.3);
}

/* 词卡样式 */
.word-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  margin: 1.5rem 0;
  text-align: center;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
  transition: var(--transition);
}

.word-card:hover {
  border-color: var(--accent-primary);
  box-shadow: 0 12px 32px rgba(0, 102, 255, 0.15);
}

.practice-card {
  background: rgba(20, 20, 20, 0.5);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}