/* ===== Reset & Base ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #4CAF50;
  --primary-dark: #388E3C;
  --primary-light: #81C784;
  --accent: #FF9800;
  --text: #333333;
  --text-light: #666666;
  --text-muted: #999999;
  --bg: #ffffff;
  --bg-soft: #f8faf8;
  --bg-dark: #1a1a2e;
  --border: #e8e8e8;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 48px rgba(0,0,0,0.12);
  --radius: 16px;
  --radius-sm: 8px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  overflow-x: hidden;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== Navbar ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 16px 0;
  transition: var(--transition);
}

.navbar.scrolled {
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(20px);
  box-shadow: 0 2px 20px rgba(0,0,0,0.06);
  padding: 10px 0;
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--bg);
  transition: var(--transition);
}

.navbar.scrolled .logo {
  color: var(--text);
}

.logo-icon {
  font-size: 1.8rem;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 36px;
}

.nav-links a {
  text-decoration: none;
  color: rgba(255,255,255,0.85);
  font-size: 0.95rem;
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: var(--transition);
}

.nav-links a:hover::after {
  width: 100%;
}

.navbar.scrolled .nav-links a {
  color: var(--text-light);
}

.navbar.scrolled .nav-links a:hover {
  color: var(--primary);
}

.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.mobile-menu-btn span {
  display: block;
  width: 24px;
  height: 2px;
  background: white;
  border-radius: 2px;
  transition: var(--transition);
}

.navbar.scrolled .mobile-menu-btn span {
  background: var(--text);
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #1a5e1f 0%, #4CAF50 40%, #66BB6A 70%, #81C784 100%);
  z-index: -1;
}

.hero-bg::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 80%;
  height: 200%;
  background: radial-gradient(ellipse, rgba(255,255,255,0.08) 0%, transparent 70%);
  animation: float 8s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50% { transform: translateY(-30px) rotate(2deg); }
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
  padding: 120px 24px 80px;
}

.hero-text {
  color: white;
}

.hero-title {
  font-size: 3.2rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.hero-title .highlight {
  background: linear-gradient(135deg, #FFD54F, #FF9800);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.15rem;
  line-height: 1.8;
  opacity: 0.9;
  margin-bottom: 36px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  margin-bottom: 48px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 32px;
  border-radius: 50px;
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: white;
  color: var(--primary-dark);
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(0,0,0,0.2);
}

.btn-outline {
  background: transparent;
  color: white;
  border: 2px solid rgba(255,255,255,0.5);
}

.btn-outline:hover {
  background: rgba(255,255,255,0.1);
  border-color: white;
}

.hero-stats {
  display: flex;
  gap: 40px;
}

.stat-item {
  text-align: center;
}

.stat-number {
  font-size: 2.2rem;
  font-weight: 800;
  display: block;
}

.stat-suffix {
  font-size: 1.4rem;
  font-weight: 700;
}

.stat-label {
  font-size: 0.85rem;
  opacity: 0.8;
  display: block;
  margin-top: 4px;
}

/* Phone Mockup */
.hero-visual {
  display: flex;
  justify-content: center;
}

.phone-mockup {
  width: 280px;
  height: 560px;
  background: #1a1a1a;
  border-radius: 40px;
  padding: 12px;
  box-shadow: 0 30px 80px rgba(0,0,0,0.3), inset 0 0 0 2px rgba(255,255,255,0.1);
  animation: phoneFloat 6s ease-in-out infinite;
}

@keyframes phoneFloat {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-15px); }
}

.phone-screen {
  width: 100%;
  height: 100%;
  background: linear-gradient(180deg, #f0f7f0 0%, #ffffff 100%);
  border-radius: 30px;
  padding: 32px 20px 20px;
  overflow: hidden;
}

.mock-header {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--primary-dark);
  margin-bottom: 20px;
  text-align: center;
}

.mock-word-card {
  background: white;
  border-radius: 16px;
  padding: 24px 16px;
  box-shadow: 0 4px 16px rgba(76,175,80,0.1);
  margin-bottom: 16px;
}

.mock-word {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--text);
  margin-bottom: 4px;
}

.mock-phonetic {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.mock-meaning {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-bottom: 16px;
}

.mock-progress {
  height: 6px;
  background: #e8f5e9;
  border-radius: 3px;
  overflow: hidden;
  margin-bottom: 8px;
}

.mock-progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--primary-light));
  border-radius: 3px;
  animation: progressGrow 2s ease-out;
}

@keyframes progressGrow {
  from { width: 0; }
}

.mock-progress-text {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-align: right;
}

.mock-actions {
  display: flex;
  gap: 10px;
}

.mock-btn {
  flex: 1;
  padding: 10px;
  border-radius: 10px;
  text-align: center;
  font-size: 0.8rem;
  font-weight: 600;
}

.mock-btn-familiar {
  background: var(--primary);
  color: white;
}

.mock-btn-review {
  background: #FFF3E0;
  color: var(--accent);
}

.hero-wave {
  position: absolute;
  bottom: -1px;
  left: 0;
  right: 0;
}

.hero-wave svg {
  display: block;
  width: 100%;
  height: 80px;
}

/* ===== Section Common ===== */
.section-header {
  text-align: center;
  margin-bottom: 60px;
}

.section-tag {
  display: inline-block;
  padding: 6px 16px;
  background: rgba(76,175,80,0.1);
  color: var(--primary);
  border-radius: 50px;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.section-title {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--text);
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-light);
}

/* ===== Features ===== */
.features {
  padding: 100px 0;
  background: var(--bg);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-soft);
  border-radius: var(--radius);
  padding: 36px 28px;
  transition: var(--transition);
  border: 1px solid transparent;
}

.feature-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(76,175,80,0.2);
  background: white;
}

.feature-icon {
  font-size: 2.6rem;
  margin-bottom: 18px;
  display: block;
}

.feature-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text);
}

.feature-card p {
  font-size: 0.92rem;
  color: var(--text-light);
  line-height: 1.7;
}

/* ===== How it works ===== */
.how-it-works {
  padding: 100px 0;
  background: var(--bg-soft);
}

.steps {
  max-width: 700px;
  margin: 0 auto;
}

.step {
  display: flex;
  align-items: flex-start;
  gap: 24px;
  padding: 24px;
  background: white;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.step:hover {
  transform: translateX(8px);
  box-shadow: var(--shadow-lg);
}

.step-number {
  font-size: 2rem;
  font-weight: 900;
  color: var(--primary);
  opacity: 0.3;
  min-width: 56px;
  line-height: 1;
  padding-top: 4px;
}

.step-content h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.step-content p {
  font-size: 0.9rem;
  color: var(--text-light);
  line-height: 1.6;
}

.step-line {
  width: 2px;
  height: 32px;
  background: linear-gradient(to bottom, var(--primary-light), transparent);
  margin: 0 auto;
}

/* ===== Showcase ===== */
.showcase {
  padding: 100px 0;
  background: var(--bg);
}

.showcase-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.showcase-item {
  transition: var(--transition);
}

.showcase-item:hover {
  transform: translateY(-4px);
}

.showcase-card {
  background: var(--bg-soft);
  border-radius: var(--radius);
  padding: 32px 20px;
  text-align: center;
  border: 1px solid var(--border);
  transition: var(--transition);
  height: 100%;
}

.showcase-card:hover {
  border-color: var(--primary-light);
  box-shadow: var(--shadow);
}

.showcase-emoji {
  font-size: 2.4rem;
  margin-bottom: 14px;
}

.showcase-card h4 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.showcase-card p {
  font-size: 0.85rem;
  color: var(--text-light);
  line-height: 1.6;
}

/* ===== Contact ===== */
.contact {
  padding: 100px 0;
  background: linear-gradient(135deg, #f0f7f0 0%, #e8f5e9 100%);
}

.contact-wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.contact-desc {
  font-size: 1.05rem;
  color: var(--text-light);
  line-height: 1.8;
  margin: 20px 0 32px;
}

.contact-details {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 16px;
}

.contact-icon {
  font-size: 1.6rem;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: white;
  border-radius: 12px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.contact-item strong {
  display: block;
  font-size: 0.9rem;
  margin-bottom: 2px;
}

.contact-item p {
  font-size: 0.88rem;
  color: var(--text-light);
}

/* QR Code */
.qr-section {
  display: flex;
  justify-content: center;
}

.qr-card {
  background: white;
  border-radius: 24px;
  padding: 40px;
  text-align: center;
  box-shadow: var(--shadow-lg);
}

.qr-image-wrapper {
  width: 220px;
  height: 220px;
  position: relative;
  margin-bottom: 16px;
}

.qr-image {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border-radius: 12px;
}

.qr-placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: #f5f5f5;
  border-radius: 12px;
  border: 2px dashed #ddd;
  color: var(--text-muted);
}

.qr-placeholder p {
  font-size: 0.9rem;
  font-weight: 600;
  margin-top: 12px;
  color: var(--text-light);
}

.qr-placeholder span {
  font-size: 0.75rem;
  margin-top: 6px;
  text-align: center;
  line-height: 1.5;
}

.qr-tip {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ===== Footer ===== */
.footer {
  background: var(--bg-dark);
  color: rgba(255,255,255,0.8);
  padding: 60px 0 30px;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding-bottom: 30px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
  margin-bottom: 24px;
}

.footer-brand .logo-icon {
  font-size: 2rem;
}

.footer-brand .logo-text {
  font-size: 1.3rem;
  font-weight: 700;
  color: white;
}

.footer-slogan {
  font-size: 0.85rem;
  opacity: 0.6;
  margin-top: 8px;
}

.footer-links {
  display: flex;
  gap: 60px;
}

.footer-col {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-col h4 {
  font-size: 0.9rem;
  font-weight: 700;
  color: white;
  margin-bottom: 6px;
}

.footer-col a {
  text-decoration: none;
  color: rgba(255,255,255,0.6);
  font-size: 0.85rem;
  transition: var(--transition);
}

.footer-col a:hover {
  color: var(--primary-light);
}

.footer-bottom {
  text-align: center;
  font-size: 0.8rem;
  opacity: 0.5;
}

/* ===== Scroll Animation ===== */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 40px;
  }
  .hero-actions {
    justify-content: center;
  }
  .hero-stats {
    justify-content: center;
  }
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .showcase-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .contact-wrapper {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .contact-info .section-title {
    text-align: center !important;
  }
}

@media (max-width: 768px) {
  .hero-title {
    font-size: 2.2rem;
  }
  .hero-subtitle {
    font-size: 1rem;
  }
  .hero-subtitle br {
    display: none;
  }
  .section-title {
    font-size: 1.8rem;
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .showcase-grid {
    grid-template-columns: 1fr 1fr;
  }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: white;
    flex-direction: column;
    padding: 20px 24px;
    gap: 16px;
    box-shadow: var(--shadow);
  }
  .nav-links.active {
    display: flex;
  }
  .nav-links a {
    color: var(--text) !important;
  }
  .mobile-menu-btn {
    display: flex;
  }
  .phone-mockup {
    width: 220px;
    height: 440px;
  }
  .hero-stats {
    gap: 24px;
  }
  .stat-number {
    font-size: 1.6rem;
  }
  .footer-content {
    flex-direction: column;
    gap: 30px;
    align-items: center;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.8rem;
  }
  .hero-actions {
    flex-direction: column;
    align-items: center;
  }
  .showcase-grid {
    grid-template-columns: 1fr;
  }
  .hero-stats {
    flex-direction: column;
    gap: 16px;
  }
}