/* =========================================
   学习网 - 访客着陆页样式
   高颜值营销级 Landing Page
   ========================================= */

/* ── 重置 ── */
.welcome-page {
  margin: 0;
  font-family: var(--font-main);
  background: #f8fafc;
  color: var(--text-primary);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* =========================================
   顶部导航栏
   ========================================= */
.welcome-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 40px;
  height: 64px;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0,0,0,0.06);
  transition: all 0.3s ease;
}
.welcome-nav.scrolled {
  box-shadow: 0 1px 20px rgba(0,0,0,0.08);
  background: rgba(255,255,255,0.95);
}
.welcome-nav .nav-brand {
  display: flex; align-items: center; gap: 10px;
  font-size: 20px; font-weight: 800; color: #1e293b;
  text-decoration: none;
}
.welcome-nav .nav-brand .brand-icon { font-size: 28px; }
.welcome-nav .nav-actions {
  display: flex; align-items: center; gap: 12px;
}
.welcome-nav .btn-nav-login {
  padding: 8px 20px;
  border-radius: 8px;
  font-size: 14px; font-weight: 600;
  border: 1.5px solid #d1d5db;
  background: #fff;
  color: #374151;
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
  display: inline-flex; align-items: center; gap: 6px;
}
.welcome-nav .btn-nav-login:hover {
  border-color: #6366f1;
  color: #4f46e5;
  background: #f5f3ff;
}
.welcome-nav .btn-nav-register {
  padding: 8px 20px;
  border-radius: 8px;
  font-size: 14px; font-weight: 600;
  border: none;
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  color: #fff;
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
  display: inline-flex; align-items: center; gap: 6px;
  box-shadow: 0 2px 8px rgba(99,102,241,0.3);
}
.welcome-nav .btn-nav-register:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 14px rgba(99,102,241,0.4);
}

/* =========================================
   Hero 横幅
   ========================================= */
.welcome-hero {
  padding: 100px 40px 80px;
  text-align: center;
  background: linear-gradient(160deg, #eef2ff 0%, #f0f4ff 25%, #ecfeff 50%, #f5f3ff 75%, #fef3c7 100%);
  position: relative;
  overflow: hidden;
}
.welcome-hero::before {
  content: '';
  position: absolute;
  top: -50%; right: -20%;
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(99,102,241,0.08) 0%, transparent 70%);
  border-radius: 50%;
}
.welcome-hero::after {
  content: '';
  position: absolute;
  bottom: -30%; left: -15%;
  width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(139,92,246,0.06) 0%, transparent 70%);
  border-radius: 50%;
}
.welcome-hero .hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 18px;
  background: rgba(99,102,241,0.08);
  border: 1px solid rgba(99,102,241,0.15);
  border-radius: 50px;
  font-size: 13px; font-weight: 600; color: #4f46e5;
  margin-bottom: 24px;
  position: relative; z-index: 1;
}
.welcome-hero .hero-badge .badge-dot {
  width: 8px; height: 8px;
  background: #22c55e;
  border-radius: 50%;
  animation: pulse-dot 2s infinite;
}
@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(1.3); }
}
.welcome-hero h1 {
  font-size: 48px; font-weight: 900; line-height: 1.2;
  color: #0f172a;
  margin: 0 auto 16px;
  max-width: 700px;
  position: relative; z-index: 1;
}
.welcome-hero h1 .highlight {
  background: linear-gradient(135deg, #6366f1, #a855f7);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.welcome-hero .hero-subtitle {
  font-size: 17px; color: #64748b;
  max-width: 560px; margin: 0 auto 36px;
  line-height: 1.7;
  position: relative; z-index: 1;
}
.welcome-hero .hero-cta {
  display: flex; align-items: center; justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  position: relative; z-index: 1;
}
.welcome-hero .btn-cta-primary {
  padding: 14px 36px;
  border-radius: 14px;
  font-size: 16px; font-weight: 700;
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  color: #fff;
  border: none;
  cursor: pointer;
  text-decoration: none;
  display: inline-flex; align-items: center; gap: 8px;
  box-shadow: 0 4px 20px rgba(99,102,241,0.35);
  transition: all 0.2s ease;
}
.welcome-hero .btn-cta-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(99,102,241,0.45);
}
.welcome-hero .btn-cta-secondary {
  padding: 14px 36px;
  border-radius: 14px;
  font-size: 16px; font-weight: 600;
  background: #fff;
  color: #4f46e5;
  border: 2px solid #e0e7ff;
  cursor: pointer;
  text-decoration: none;
  display: inline-flex; align-items: center; gap: 8px;
  transition: all 0.2s ease;
}
.welcome-hero .btn-cta-secondary:hover {
  background: #f5f3ff;
  border-color: #c7d2fe;
}

/* Hero 装饰数字 */
.hero-floating-icons {
  position: absolute; inset: 0;
  pointer-events: none; z-index: 0;
}
.hero-floating-icons .float-icon {
  position: absolute;
  font-size: 40px;
  opacity: 0.15;
  animation: float-around 20s linear infinite;
}
.hero-floating-icons .float-icon:nth-child(1) { top: 15%; left: 8%; animation-delay: 0s; font-size: 36px; }
.hero-floating-icons .float-icon:nth-child(2) { top: 60%; left: 5%; animation-delay: -5s; font-size: 44px; }
.hero-floating-icons .float-icon:nth-child(3) { top: 20%; right: 8%; animation-delay: -10s; font-size: 38px; }
.hero-floating-icons .float-icon:nth-child(4) { top: 65%; right: 5%; animation-delay: -15s; font-size: 42px; }
.hero-floating-icons .float-icon:nth-child(5) { top: 40%; left: 45%; animation-delay: -3s; font-size: 32px; }
@keyframes float-around {
  0% { transform: translateY(0) rotate(0deg); }
  25% { transform: translateY(-12px) rotate(3deg); }
  50% { transform: translateY(0) rotate(0deg); }
  75% { transform: translateY(8px) rotate(-3deg); }
  100% { transform: translateY(0) rotate(0deg); }
}

/* =========================================
   平台数据统计条
   ========================================= */
.welcome-stats {
  display: flex; align-items: center; justify-content: center;
  gap: 48px;
  padding: 32px 40px;
  background: #fff;
  border-bottom: 1px solid #f1f5f9;
  flex-wrap: wrap;
}
.welcome-stats .stat-item {
  text-align: center;
}
.welcome-stats .stat-num {
  font-size: 32px; font-weight: 900;
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.welcome-stats .stat-label {
  font-size: 13px; color: #94a3b8; margin-top: 2px; font-weight: 500;
}
.welcome-stats .stat-divider {
  width: 1px; height: 40px; background: #e2e8f0;
}

/* =========================================
   通用区块
   ========================================= */
.welcome-section {
  padding: 72px 40px;
  max-width: 1100px;
  margin: 0 auto;
}
.welcome-section .section-tag {
  display: inline-block;
  padding: 4px 14px;
  background: rgba(99,102,241,0.08);
  color: #4f46e5;
  border-radius: 50px;
  font-size: 12px; font-weight: 700;
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.welcome-section .section-title {
  font-size: 32px; font-weight: 800; color: #0f172a;
  margin: 0 0 12px;
}
.welcome-section .section-desc {
  font-size: 15px; color: #64748b; line-height: 1.7;
  max-width: 600px; margin: 0 0 40px;
}

/* =========================================
   学段选择标签页
   ========================================= */
.stage-tabs {
  display: flex; gap: 8px; margin-bottom: 32px;
  background: #f1f5f9; padding: 5px;
  border-radius: 14px;
  width: fit-content;
}
.stage-tab {
  padding: 10px 24px;
  border-radius: 10px;
  font-size: 14px; font-weight: 600;
  border: none; background: transparent;
  color: #64748b;
  cursor: pointer;
  transition: all 0.15s ease;
  display: flex; align-items: center; gap: 6px;
}
.stage-tab.active {
  background: #fff;
  color: #4f46e5;
  box-shadow: 0 1px 4px rgba(0,0,0,0.06), 0 2px 8px rgba(0,0,0,0.04);
}

/* =========================================
   学科预览卡片网格
   ========================================= */
.subject-preview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 14px;
}
.subject-preview-card {
  background: #fff;
  border: 1px solid #f1f5f9;
  border-radius: 14px;
  padding: 24px 20px;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
  color: inherit;
  display: flex; flex-direction: column; align-items: center;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.subject-preview-card::after {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  opacity: 0;
  transition: opacity 0.2s ease;
}
.subject-preview-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(0,0,0,0.08);
  border-color: #e2e8f0;
}
.subject-preview-card:hover::after { opacity: 1; }
.subject-preview-card .preview-icon {
  font-size: 36px;
  width: 64px; height: 64px;
  border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 14px;
}
.subject-preview-card .preview-name {
  font-size: 15px; font-weight: 700; color: #1e293b; margin-bottom: 4px;
}
.subject-preview-card .preview-range {
  font-size: 12px; color: #94a3b8;
}
.subject-preview-card .preview-count {
  margin-top: 8px;
  font-size: 11px; font-weight: 600; color: #6366f1;
  background: rgba(99,102,241,0.08);
  padding: 3px 10px; border-radius: 50px;
}

/* 各学科卡片主题色 */
.sp-card-chinese    .preview-icon { background: #ecfdf5; } .sp-card-chinese::after    { background: #10b981; }
.sp-card-math       .preview-icon { background: #eff6ff; } .sp-card-math::after       { background: #3b82f6; }
.sp-card-english    .preview-icon { background: #fff7ed; } .sp-card-english::after    { background: #f97316; }
.sp-card-aoshu      .preview-icon { background: #faf5ff; } .sp-card-aoshu::after      { background: #a855f7; }
.sp-card-mid-chinese .preview-icon { background: #ecfdf5; } .sp-card-mid-chinese::after { background: #059669; }
.sp-card-mid-math   .preview-icon { background: #eff6ff; } .sp-card-mid-math::after   { background: #2563eb; }
.sp-card-mid-eng    .preview-icon { background: #fff7ed; } .sp-card-mid-eng::after    { background: #ea580c; }
.sp-card-mid-physics  .preview-icon { background: #f0f9ff; } .sp-card-mid-physics::after  { background: #0284c7; }
.sp-card-mid-chem   .preview-icon { background: #fefce8; } .sp-card-mid-chem::after   { background: #ca8a04; }
.sp-card-high-math    .preview-icon { background: #eef2ff; } .sp-card-high-math::after    { background: #4f46e5; }
.sp-card-high-eng     .preview-icon { background: #fff1f2; } .sp-card-high-eng::after     { background: #e11d48; }
.sp-card-high-physics  .preview-icon { background: #eff6ff; } .sp-card-high-physics::after  { background: #1d4ed8; }
.sp-card-high-chem   .preview-icon { background: #f5f3ff; } .sp-card-high-chem::after   { background: #7c3aed; }
.sp-card-high-bio    .preview-icon { background: #ecfdf5; } .sp-card-high-bio::after    { background: #059669; }

/* =========================================
   AI 教学特色
   ========================================= */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.feature-card {
  background: #fff;
  border: 1px solid #f1f5f9;
  border-radius: 16px;
  padding: 32px 24px;
  transition: all 0.2s ease;
}
.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(0,0,0,0.06);
}
.feature-card .ft-icon {
  font-size: 36px;
  width: 56px; height: 56px;
  border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 20px;
}
.feature-card .ft-title {
  font-size: 17px; font-weight: 700; color: #1e293b; margin-bottom: 8px;
}
.feature-card .ft-desc {
  font-size: 14px; color: #64748b; line-height: 1.7;
}
.feature-card .ft-icon.ft-ai      { background: #eef2ff; }
.feature-card .ft-icon.ft-star    { background: #fefce8; }
.feature-card .ft-icon.ft-review  { background: #fef2f2; }

/* =========================================
   教学流程展示
   ========================================= */
.teach-flow {
  display: flex; align-items: center; gap: 0;
  background: #fff; border: 1px solid #f1f5f9;
  border-radius: 20px; padding: 40px 32px;
  overflow-x: auto;
}
.teach-flow .flow-step {
  display: flex; align-items: center; gap: 12px;
  flex-shrink: 0;
}
.teach-flow .flow-num {
  width: 36px; height: 36px;
  border-radius: 50%;
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-size: 15px; font-weight: 800;
  flex-shrink: 0;
}
.teach-flow .flow-text {
  font-size: 14px; font-weight: 600; color: #334155;
  white-space: nowrap;
}
.teach-flow .flow-arrow {
  margin: 0 20px;
  font-size: 18px; color: #cbd5e1;
  flex-shrink: 0;
}

/* =========================================
   CTA 底部
   ========================================= */
.welcome-cta-section {
  padding: 80px 40px;
  text-align: center;
  background: linear-gradient(160deg, #eef2ff 0%, #f5f3ff 100%);
  position: relative;
  overflow: hidden;
}
.welcome-cta-section::before {
  content: '';
  position: absolute;
  top: -40%; left: 50%;
  transform: translateX(-50%);
  width: 800px; height: 800px;
  background: radial-gradient(circle, rgba(99,102,241,0.06) 0%, transparent 70%);
  border-radius: 50%;
}
.welcome-cta-section h2 {
  font-size: 32px; font-weight: 800; color: #0f172a;
  margin: 0 0 12px;
  position: relative; z-index: 1;
}
.welcome-cta-section p {
  font-size: 15px; color: #64748b; margin: 0 0 32px;
  position: relative; z-index: 1;
}
.welcome-cta-section .cta-buttons {
  display: flex; align-items: center; justify-content: center;
  gap: 16px; flex-wrap: wrap;
  position: relative; z-index: 1;
}

/* =========================================
   页脚
   ========================================= */
.welcome-footer {
  padding: 32px 40px;
  text-align: center;
  background: #fff;
  border-top: 1px solid #f1f5f9;
  font-size: 13px; color: #94a3b8;
}

/* =========================================
   响应式
   ========================================= */
@media (max-width: 768px) {
  .welcome-nav {
    padding: 0 20px; height: 56px;
  }
  .welcome-nav .nav-brand {
    font-size: 17px;
  }
  .welcome-nav .nav-brand .brand-icon { font-size: 24px; }
  .welcome-nav .btn-nav-login,
  .welcome-nav .btn-nav-register {
    padding: 6px 14px; font-size: 13px;
  }

  .welcome-hero {
    padding: 100px 20px 56px;
  }
  .welcome-hero h1 {
    font-size: 30px;
  }
  .welcome-hero .hero-subtitle {
    font-size: 15px;
  }
  .welcome-hero .btn-cta-primary,
  .welcome-hero .btn-cta-secondary {
    padding: 12px 24px; font-size: 14px;
  }

  .welcome-section {
    padding: 48px 20px;
  }
  .welcome-section .section-title {
    font-size: 24px;
  }

  .welcome-stats {
    gap: 24px; padding: 24px 20px;
  }
  .welcome-stats .stat-num { font-size: 24px; }
  .welcome-stats .stat-divider { display: none; }

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

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

  .teach-flow {
    flex-direction: column; align-items: flex-start;
    gap: 16px; padding: 28px 20px;
  }
  .teach-flow .flow-arrow {
    transform: rotate(90deg);
    margin: 4px 0 4px 16px;
  }

  .welcome-cta-section {
    padding: 56px 20px;
  }
  .welcome-cta-section h2 { font-size: 24px; }

  .welcome-footer { padding: 24px 20px; }
}