/* ==========================================================================
   悠兔机场 (youtu-jichang.homes) - Muji Minimalist & Raw Cotton Canvas CSS
   风格：日系极简无印便签 (B5 Canvas & Muji Stationery)
   ========================================================================== */

:root {
  /* 核心色彩（无印自然色彩系统） */
  --bg-linen: #F3EFEA;           /* 天然亚麻米白底色 */
  --bg-paper: #FAF8F5;           /* B5 便签卡片纸白 */
  --bg-paper-alt: #F7F4EE;       /* 次级纸质卡片背景 */
  --bg-paper-hover: #FFFFFF;     /* 便签悬浮纯净白 */
  --text-main: #5A4D41;          /* 浅胡桃木色主文字 */
  --text-sub: #76685A;           /* 暖灰胡桃木次级文字 */
  --text-muted: #9E9084;         /* 柔和木色辅助文字 */
  --stamp-red: #B84A39;          /* 朱砂红单线印章 accent */
  --stamp-red-bg: #FDF4F2;       /* 朱砂红微沉淀底色 */
  --grid-line: #E6E0D8;          /* 浅灰方格网格线 */
  --border-paper: #E2DACF;       /* 便签边框 */
  --border-dotted: #C8BEB3;      /* 打孔线 / 虚线撕裂边框 */
  
  /* 影子与质感 */
  --shadow-paper: 0 4px 16px rgba(90, 77, 65, 0.05), 0 1px 3px rgba(90, 77, 65, 0.04);
  --shadow-paper-hover: 0 12px 32px rgba(90, 77, 65, 0.09), 0 2px 6px rgba(90, 77, 65, 0.05);
  --radius-card: 12px;
  --radius-btn: 6px;
  
  /* 字体与间距 */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --transition-smooth: cubic-bezier(0.25, 1, 0.5, 1);
}

/* 基础重置 */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  background-color: var(--bg-linen);
  color: var(--text-main);
  font-family: var(--font-family);
  line-height: 1.75;
  letter-spacing: 0.02em;
  -webkit-font-smoothing: antialiased;
  background-image: 
    linear-gradient(to right, rgba(230, 224, 216, 0.4) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(230, 224, 216, 0.4) 1px, transparent 1px);
  background-size: 32px 32px;
  min-height: 100vh;
  position: relative;
}

/* 全局容器 */
.container {
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 24px;
}

/* 链接基础样式 */
a {
  color: var(--text-main);
  text-decoration: none;
  transition: color 0.25s ease, border-color 0.25s ease;
}

a:hover {
  color: var(--stamp-red);
}

/* 头部导航 Header & Navbar */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(243, 239, 234, 0.92);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-paper);
  padding: 14px 0;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* 品牌 Logo 与朱砂红印章 */
.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: 0.05em;
}

.seal-stamp-icon {
  width: 36px;
  height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1.5px solid var(--stamp-red);
  border-radius: 6px;
  color: var(--stamp-red);
  padding: 2px;
  background-color: var(--stamp-red-bg);
  box-shadow: inset 0 0 0 1px rgba(184, 74, 57, 0.15);
}

/* 导航链接 */
.nav-menu {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav-link {
  font-size: 0.95rem;
  color: var(--text-sub);
  font-weight: 500;
  padding: 4px 0;
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 1.5px;
  background-color: var(--stamp-red);
  transition: width 0.3s var(--transition-smooth);
}

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

/* 统一 CTA 按钮 */
.btn-stamp {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  background-color: var(--stamp-red);
  color: #FFFFFF !important;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 10px 22px;
  border-radius: var(--radius-btn);
  border: 1px solid #A03B2B;
  box-shadow: 0 2px 6px rgba(184, 74, 57, 0.25);
  transition: all 0.25s var(--transition-smooth);
  cursor: pointer;
}

.btn-stamp:hover {
  background-color: #A33C2D;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(184, 74, 57, 0.35);
}

.btn-wood {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  background-color: var(--bg-paper);
  color: var(--text-main) !important;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 10px 22px;
  border-radius: var(--radius-btn);
  border: 1px solid var(--border-paper);
  box-shadow: var(--shadow-paper);
  transition: all 0.25s var(--transition-smooth);
}

.btn-wood:hover {
  border-color: var(--stamp-red);
  color: var(--stamp-red) !important;
  background-color: #FFFFFF;
  transform: translateY(-1px);
}

/* 首屏 Hero Section */
.hero-section {
  padding: 60px 0 80px;
  position: relative;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 0.85rem;
  color: var(--stamp-red);
  font-weight: 600;
  margin-bottom: 24px;
}

.hero-title {
  font-size: 2.5rem;
  line-height: 1.3;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 20px;
  letter-spacing: -0.01em;
}

.hero-title span {
  color: var(--stamp-red);
  position: relative;
}

.hero-desc {
  font-size: 1.05rem;
  color: var(--text-sub);
  line-height: 1.8;
  margin-bottom: 32px;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 40px;
}

/* B5 便签卡片基础元件 */
.b5-card {
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  border-radius: var(--radius-card);
  padding: 32px;
  box-shadow: var(--shadow-paper);
  position: relative;
  transition: transform 0.3s var(--transition-smooth), box-shadow 0.3s var(--transition-smooth);
}

.b5-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-paper-hover);
}

/* 便签打孔线与顶部装饰线 */
.b5-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 24px;
  right: 24px;
  height: 3px;
  background: repeating-linear-gradient(90deg, var(--border-dotted) 0, var(--border-dotted) 8px, transparent 8px, transparent 14px);
}

/* 标记印章标头 */
.stamp-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--stamp-red);
  border: 1px solid var(--stamp-red);
  padding: 2px 8px;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 12px;
  background-color: var(--stamp-red-bg);
}

/* 通用 Section 标题 */
.section-header {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 48px;
}

.section-title {
  font-size: 2rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 12px;
}

.section-subtitle {
  font-size: 1rem;
  color: var(--text-sub);
  line-height: 1.7;
}

/* 核心优势网格 */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 60px;
}

.feature-b5 {
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  border-radius: var(--radius-card);
  padding: 28px;
  box-shadow: var(--shadow-paper);
  position: relative;
  overflow: hidden;
}

.feature-num {
  font-size: 2rem;
  font-weight: 900;
  color: rgba(184, 74, 57, 0.18);
  position: absolute;
  top: 16px;
  right: 20px;
  font-family: serif;
}

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: 8px;
  background-color: var(--stamp-red-bg);
  border: 1px solid rgba(184, 74, 57, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  color: var(--stamp-red);
  font-weight: 700;
}

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

.feature-desc {
  font-size: 0.92rem;
  color: var(--text-sub);
  line-height: 1.7;
}

/* 套餐价格 Section */
.pricing-section {
  padding: 70px 0;
  background-color: rgba(247, 244, 238, 0.6);
  border-top: 1px dashed var(--border-paper);
  border-bottom: 1px dashed var(--border-paper);
}

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

.pricing-b5 {
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  border-radius: var(--radius-card);
  padding: 36px 28px;
  box-shadow: var(--shadow-paper);
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all 0.3s var(--transition-smooth);
}

.pricing-b5.featured {
  border: 2px solid var(--stamp-red);
  background-color: #FFFFFF;
  transform: scale(1.02);
}

.pricing-b5.featured::after {
  content: '热门推荐';
  position: absolute;
  top: -14px;
  right: 24px;
  background-color: var(--stamp-red);
  color: #FFFFFF;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 12px;
  letter-spacing: 0.05em;
}

.price-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
}

.price-box {
  display: flex;
  align-items: baseline;
  gap: 4px;
  margin: 16px 0 8px;
}

.price-symbol {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--stamp-red);
}

.price-amount {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--text-main);
  line-height: 1;
}

.price-note {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px dashed var(--border-paper);
}

.price-features {
  list-style: none;
  margin-bottom: 32px;
  flex-grow: 1;
}

.price-features li {
  font-size: 0.92rem;
  color: var(--text-sub);
  padding: 8px 0;
  display: flex;
  align-items: center;
  gap: 8px;
}

.price-features li span {
  color: var(--stamp-red);
  font-weight: 700;
}

/* 教程 Tab 样式 */
.tutorial-section {
  padding: 80px 0;
}

.tutorial-tabs {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-bottom: 36px;
  flex-wrap: wrap;
}

.tab-btn {
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  padding: 10px 24px;
  border-radius: 20px;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-sub);
  cursor: pointer;
  transition: all 0.25s ease;
}

.tab-btn.active, .tab-btn:hover {
  background-color: var(--stamp-red);
  color: #FFFFFF;
  border-color: var(--stamp-red);
}

.tutorial-panel {
  display: none;
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  border-radius: var(--radius-card);
  padding: 36px;
  box-shadow: var(--shadow-paper);
}

.tutorial-panel.active {
  display: block;
}

.step-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.step-item {
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 20px;
  align-items: start;
}

.step-num {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background-color: var(--stamp-red-bg);
  border: 1px solid var(--stamp-red);
  color: var(--stamp-red);
  font-weight: 800;
  font-size: 1.1rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.step-info h4 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
}

.step-info p {
  font-size: 0.95rem;
  color: var(--text-sub);
  line-height: 1.7;
}

/* FAQ 手风琴 */
.faq-section {
  padding: 70px 0;
}

.faq-grid {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 860px;
  margin: 0 auto;
}

.faq-b5 {
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  border-radius: 10px;
  overflow: hidden;
  box-shadow: var(--shadow-paper);
  transition: border-color 0.25s ease;
}

.faq-header {
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  user-select: none;
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text-main);
}

.faq-header:hover {
  color: var(--stamp-red);
}

.faq-icon {
  font-size: 1.3rem;
  color: var(--stamp-red);
  transition: transform 0.3s ease;
}

.faq-b5.active .faq-icon {
  transform: rotate(45deg);
}

.faq-body {
  display: none;
  padding: 0 24px 20px;
  font-size: 0.95rem;
  color: var(--text-sub);
  line-height: 1.8;
  border-top: 1px dashed var(--border-paper);
  padding-top: 16px;
}

.faq-b5.active .faq-body {
  display: block;
}

/* 文章预览卡片 */
.articles-preview-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  margin-bottom: 40px;
}

.article-b5-card {
  background-color: var(--bg-paper);
  border: 1px solid var(--border-paper);
  border-radius: var(--radius-card);
  overflow: hidden;
  box-shadow: var(--shadow-paper);
  display: flex;
  flex-direction: column;
  transition: transform 0.3s var(--transition-smooth), box-shadow 0.3s var(--transition-smooth);
}

.article-b5-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-paper-hover);
}

.article-cover {
  width: 100%;
  height: 180px;
  object-fit: cover;
  border-bottom: 1px solid var(--border-paper);
}

.article-content {
  padding: 24px;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.article-meta .tag {
  color: var(--stamp-red);
  font-weight: 600;
}

.article-title-text {
  font-size: 1.1rem;
  font-weight: 700;
  line-height: 1.5;
  color: var(--text-main);
  margin-bottom: 12px;
}

.article-title-text a:hover {
  color: var(--stamp-red);
}

.article-excerpt {
  font-size: 0.9rem;
  color: var(--text-sub);
  line-height: 1.7;
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-link-btn {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--stamp-red);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* 页脚 Footer */
.footer {
  background-color: var(--bg-paper-alt);
  border-top: 1px solid var(--border-paper);
  padding: 60px 0 30px;
  margin-top: 80px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 48px;
}

.footer-brand p {
  font-size: 0.9rem;
  color: var(--text-sub);
  margin-top: 16px;
  line-height: 1.8;
}

.footer-col h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 20px;
  padding-bottom: 8px;
  border-bottom: 1px dashed var(--border-paper);
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-links a {
  font-size: 0.88rem;
  color: var(--text-sub);
}

.footer-links a:hover {
  color: var(--stamp-red);
}

.footer-bottom {
  text-align: center;
  padding-top: 24px;
  border-top: 1px solid var(--border-paper);
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* 响应式调整 */
@media (max-width: 992px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }
  .features-grid, .pricing-grid, .articles-preview-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  .features-grid, .pricing-grid, .articles-preview-grid {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .hero-title {
    font-size: 1.8rem;
  }
  .pricing-b5.featured {
    transform: none;
  }
  .nav-menu {
    display: none;
  }
}