/* ==============================================================================
   吹雪云 (cxy.lol) - 全局样式规范 (黑白极简风格)
   设计语言：黑白灰、克制留白、经典纯粹、无重型依赖、极简质感
   ============================================================================== */

:root {
  --bg-body: #ffffff;
  --bg-subtle: #f8f8f9;
  --bg-card: #ffffff;
  --bg-card-hover: #fafafa;
  --text-main: #09090b;
  --text-muted: #52525b;
  --text-light: #71717a;
  --border-light: #e4e4e7;
  --border-dark: #18181b;
  --accent-black: #000000;
  --accent-white: #ffffff;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.08);
  --max-w: 1160px;
  --transition-fast: 0.18s ease;
  --transition-base: 0.25s ease;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  text-size-adjust: 100%;
}

body {
  background-color: var(--bg-body);
  color: var(--text-main);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* 键盘可访问性焦点轮廓 */
:focus-visible {
  outline: 2px solid var(--accent-black);
  outline-offset: 3px;
}

/* 链接基础样式 */
a {
  color: inherit;
  text-decoration: none;
  transition: opacity var(--transition-fast), color var(--transition-fast);
}

/* 标题样式：粗圆黑体质感 */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-main);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
}

h1 {
  font-size: clamp(2.2rem, 5vw, 3.8rem);
  letter-spacing: -0.03em;
}

h2 {
  font-size: clamp(1.75rem, 3.5vw, 2.5rem);
  margin-bottom: 0.75rem;
}

h3 {
  font-size: clamp(1.2rem, 2vw, 1.45rem);
  margin-bottom: 0.5rem;
}

p {
  color: var(--text-muted);
  font-size: 1.05rem;
  line-height: 1.7;
}

/* 容器基础 */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

.section-block {
  padding: 80px 0;
  position: relative;
}

.section-title-wrap {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 56px;
}

.section-subtitle {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-light);
  margin-bottom: 12px;
  border-bottom: 2px solid var(--text-main);
  padding-bottom: 4px;
}

/* ==============================================================================
   页眉 Header
   ============================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  transition: all var(--transition-base);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand-logo-link {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand-logo-img {
  height: 38px;
  width: auto;
  display: block;
}

.nav-menu {
  display: flex;
  align-items: center;
  list-style: none;
  gap: 32px;
}

.nav-item-link {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-muted);
  position: relative;
  padding: 8px 0;
}

.nav-item-link:hover,
.nav-item-link.active {
  color: var(--text-main);
}

.nav-item-link.highlight-nav {
  color: var(--text-main);
  font-weight: 700;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* 按钮规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  font-size: 0.95rem;
  font-weight: 700;
  border-radius: var(--radius-full);
  transition: all var(--transition-fast);
  cursor: pointer;
  white-space: nowrap;
  min-height: 44px;
  text-decoration: none;
  border: 1px solid transparent;
}

.btn-primary {
  background-color: var(--accent-black);
  color: var(--accent-white);
  border-color: var(--accent-black);
}

.btn-primary:hover {
  background-color: #27272a;
  border-color: #27272a;
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

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

.btn-outline {
  background-color: transparent;
  color: var(--text-main);
  border-color: var(--border-light);
}

.btn-outline:hover {
  border-color: var(--text-main);
  background-color: var(--bg-subtle);
}

.btn-sm {
  padding: 8px 18px;
  font-size: 0.88rem;
  min-height: 38px;
}

/* ==============================================================================
   主视觉 Hero Section
   ============================================================================== */
.hero-section {
  padding: 80px 0 100px;
  background: radial-gradient(circle at 50% 0%, #fafafa 0%, #ffffff 80%);
  border-bottom: 1px solid var(--border-light);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 60px;
  align-items: center;
}

.hero-content {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  background: var(--bg-subtle);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  width: fit-content;
}

.hero-tag-dot {
  width: 8px;
  height: 8px;
  background: #22c55e;
  border-radius: 50%;
}

.hero-desc {
  font-size: 1.15rem;
  max-width: 540px;
  line-height: 1.75;
}

.hero-btn-group {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 12px;
}

.hero-visual-card {
  position: relative;
  background: var(--bg-subtle);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.hero-stat-row {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.hero-stat-box {
  background: var(--accent-white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 18px 20px;
}

.hero-stat-number {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--text-main);
}

.hero-stat-label {
  font-size: 0.85rem;
  color: var(--text-light);
  margin-top: 2px;
}

.hero-node-badge {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--accent-white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 14px 18px;
  font-size: 0.9rem;
  font-weight: 600;
}

.badge-status {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8rem;
  color: #16a34a;
}

/* ==============================================================================
   核心优势 Features
   ============================================================================== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  transition: all var(--transition-base);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--text-main);
  box-shadow: var(--shadow-md);
}

.feature-icon-box {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: var(--bg-subtle);
  border: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-main);
  font-size: 1.35rem;
}

.feature-desc {
  font-size: 0.95rem;
  line-height: 1.65;
}

/* ==============================================================================
   流媒体与 AI 支持 Media & AI Support
   ============================================================================== */
.support-section {
  background: var(--bg-subtle);
  border-top: 1px solid var(--border-light);
  border-bottom: 1px solid var(--border-light);
}

.support-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.support-category-card {
  background: var(--accent-white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px;
}

.support-category-title {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.support-tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 20px 0;
}

.support-tag {
  background: var(--bg-subtle);
  border: 1px solid var(--border-light);
  padding: 8px 16px;
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-main);
}

.support-note {
  font-size: 0.88rem;
  color: var(--text-light);
  line-height: 1.6;
  border-top: 1px solid var(--border-light);
  padding-top: 16px;
}

/* ==============================================================================
   套餐对比 Pricing
   ============================================================================== */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 40px 32px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all var(--transition-base);
}

.pricing-card:hover {
  border-color: var(--text-main);
  box-shadow: var(--shadow-md);
}

.pricing-card.popular {
  border: 2px solid var(--accent-black);
  box-shadow: var(--shadow-lg);
}

.pricing-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--accent-black);
  color: var(--accent-white);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 14px;
  border-radius: var(--radius-full);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.pricing-plan-name {
  font-size: 1.35rem;
  margin-bottom: 8px;
}

.pricing-plan-desc {
  font-size: 0.9rem;
  margin-bottom: 24px;
}

.pricing-price-wrap {
  display: flex;
  align-items: baseline;
  gap: 6px;
  margin-bottom: 24px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-light);
}

.pricing-price {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--text-main);
  line-height: 1;
}

.pricing-period {
  font-size: 0.9rem;
  color: var(--text-light);
}

.pricing-features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: 32px;
  flex-grow: 1;
}

.pricing-feature-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.92rem;
  color: var(--text-muted);
}

.pricing-feature-item svg {
  flex-shrink: 0;
  stroke: var(--text-main);
}

.pricing-notice {
  text-align: center;
  font-size: 0.88rem;
  color: var(--text-light);
  margin-top: 36px;
}

/* ==============================================================================
   常见问题 FAQ
   ============================================================================== */
.faq-wrap {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--bg-card);
  transition: border-color var(--transition-fast);
}

.faq-item:hover {
  border-color: #a1a1aa;
}

.faq-question {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 22px 26px;
  background: transparent;
  border: none;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-main);
  text-align: left;
  cursor: pointer;
}

.faq-icon {
  width: 20px;
  height: 20px;
  transition: transform var(--transition-fast);
  stroke: var(--text-main);
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
}

.faq-answer {
  display: none;
  padding: 0 26px 22px;
  font-size: 0.98rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.faq-item.active .faq-answer {
  display: block;
}

/* ==============================================================================
   全站右侧章节切换按钮 Chapter Navigator
   ============================================================================== */
.chapter-nav {
  position: fixed;
  right: 24px;
  bottom: 40px;
  z-index: 99;
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: rgba(255, 255, 255, 0.9);
  padding: 8px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(8px);
}

.chapter-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  color: var(--text-main);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.chapter-btn:hover:not(:disabled) {
  background: var(--accent-black);
  color: var(--accent-white);
  border-color: var(--accent-black);
}

.chapter-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

/* ==============================================================================
   页脚 Footer
   ============================================================================== */
.site-footer {
  background: var(--bg-subtle);
  border-top: 1px solid var(--border-light);
  padding: 60px 0 36px;
  margin-top: 40px;
}

.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--border-light);
  flex-wrap: wrap;
  gap: 24px;
}

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

.footer-brand-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
}

.footer-brand-desc {
  font-size: 0.9rem;
  color: var(--text-light);
  max-width: 420px;
}

.footer-links-list {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
  flex-wrap: wrap;
}

.footer-link-item a {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-muted);
}

.footer-link-item a:hover {
  color: var(--text-main);
}

.footer-bottom {
  margin-top: 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--text-light);
}

/* ==============================================================================
   文章与独立单页样式 Articles & Subpages
   ============================================================================== */
.article-header {
  padding: 60px 0 40px;
  border-bottom: 1px solid var(--border-light);
  margin-bottom: 48px;
}

.article-breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.88rem;
  color: var(--text-light);
  margin-bottom: 20px;
}

.article-breadcrumb a:hover {
  color: var(--text-main);
}

.article-meta-row {
  display: flex;
  align-items: center;
  gap: 20px;
  margin-top: 18px;
  font-size: 0.9rem;
  color: var(--text-light);
  flex-wrap: wrap;
}

.article-content-body {
  max-width: 820px;
  margin: 0 auto;
  font-size: 1.1rem;
  line-height: 1.85;
}

.article-content-body h2 {
  margin-top: 48px;
  margin-bottom: 18px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-light);
}

.article-content-body h3 {
  margin-top: 36px;
  margin-bottom: 14px;
}

.article-content-body p {
  margin-bottom: 24px;
}

.article-content-body ul,
.article-content-body ol {
  margin-bottom: 24px;
  padding-left: 28px;
  color: var(--text-muted);
}

.article-content-body li {
  margin-bottom: 10px;
}

.article-content-body blockquote {
  border-left: 3px solid var(--text-main);
  padding: 16px 20px;
  background: var(--bg-subtle);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 28px 0;
  font-style: italic;
}

.article-promo-box {
  background: var(--bg-subtle);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px;
  margin: 48px 0;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.article-reference-box {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin: 36px 0;
  font-size: 0.92rem;
}

/* 文章列表页 */
.article-list-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
  margin-bottom: 60px;
}

.article-list-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-base);
}

.article-list-card:hover {
  transform: translateY(-3px);
  border-color: var(--text-main);
  box-shadow: var(--shadow-md);
}

.article-list-date {
  font-size: 0.85rem;
  color: var(--text-light);
  margin-bottom: 10px;
}

.article-list-summary {
  font-size: 0.95rem;
  margin: 12px 0 24px;
  flex-grow: 1;
}

/* ==============================================================================
   响应式规范 Responsive
   ============================================================================== */
@media (max-width: 992px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .pricing-grid {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: 0 auto;
  }
  .support-grid {
    grid-template-columns: 1fr;
  }
  .article-list-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none; /* 移动端精简头部，确保触控空间 */
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .section-block {
    padding: 60px 0;
  }
  .hero-section {
    padding: 50px 0 70px;
  }
  .chapter-nav {
    right: 16px;
    bottom: 24px;
  }
  .footer-top {
    flex-direction: column;
    align-items: flex-start;
  }
  .footer-links-list {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }
  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

/* prefers-reduced-motion 尊重系统减弱动画设置 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}