@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:ital,wght@0,400;0,600;0,700;0,800;1,400&display=swap');

/* ===== 变量 ===== */
:root {
  --mint: #b4fde1;
  --blue: #add8e6;
  --dark: #172620;
  --dark-80: rgba(23,38,32,0.8);
  --mint-deep: #7aefc4;
  --blue-deep: #7ab8cc;
  --white: #ffffff;
  --off-white: #f4fdf9;
  --radius-sm: 16px;
  --radius-md: 20px;
  --radius-lg: 24px;
  --border: 3px solid var(--dark);
  --border-thick: 4px solid var(--dark);
  --shadow-clay: 4px 4px 0 var(--dark), inset -2px -2px 8px rgba(23,38,32,0.12);
  --shadow-clay-hover: 6px 6px 0 var(--dark), inset -2px -2px 8px rgba(23,38,32,0.18);
  --shadow-press: 2px 2px 0 var(--dark), inset -1px -1px 6px rgba(23,38,32,0.1);
  --font: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --nav-h: 72px;
}

/* ===== 重置 ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; font-size: 16px; }
body { font-family: var(--font); background: var(--off-white); color: var(--dark); line-height: 1.65; overflow-x: hidden; }
body.nav-open { overflow: hidden; }
img { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

/* ===== 品牌字体 ===== */
.logo-text {
  font-size: 1.4rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--dark);
}
.site-logo-img { height: 40px; width: auto; }

/* ===== 顶部品牌栏 ===== */
.top-brand-bar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
  height: var(--nav-h);
  background: var(--mint);
  border-bottom: var(--border);
  box-shadow: 0 4px 0 var(--dark);
}
.brand-link { display: flex; align-items: center; gap: 10px; }

/* 汉堡按钮 */
.nav-toggle {
  width: 48px; height: 48px;
  border-radius: var(--radius-sm);
  border: var(--border);
  background: var(--white);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  box-shadow: var(--shadow-clay);
  transition: box-shadow 200ms ease-out, transform 200ms ease-out;
}
.nav-toggle:hover {
  box-shadow: var(--shadow-clay-hover);
  transform: translateY(-2px);
}
.nav-toggle:active {
  box-shadow: var(--shadow-press);
  transform: translateY(1px);
}
.hamburger-line {
  display: block;
  width: 22px; height: 2.5px;
  background: var(--dark);
  border-radius: 2px;
  transition: transform 200ms ease-out, opacity 200ms ease-out;
}
.nav-toggle.is-active .hamburger-line:nth-child(1) { transform: translateY(7.5px) rotate(45deg); }
.nav-toggle.is-active .hamburger-line:nth-child(2) { opacity: 0; transform: scaleX(0); }
.nav-toggle.is-active .hamburger-line:nth-child(3) { transform: translateY(-7.5px) rotate(-45deg); }

/* ===== 全屏遮罩菜单 ===== */
.fullscreen-overlay {
  position: fixed;
  inset: 0;
  z-index: 300;
  background: var(--dark);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 300ms ease-out;
}
.fullscreen-overlay.is-open {
  opacity: 1;
  pointer-events: all;
}
.nav-close {
  position: absolute;
  top: 24px; right: 32px;
  width: 52px; height: 52px;
  border-radius: var(--radius-md);
  border: var(--border);
  border-color: var(--mint);
  background: transparent;
  color: var(--mint);
  font-size: 1.4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 200ms ease-out, color 200ms ease-out;
}
.nav-close:hover { background: var(--mint); color: var(--dark); }

.overlay-nav-list { display: flex; flex-direction: column; gap: 12px; align-items: center; }
.overlay-nav-item {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 400ms cubic-bezier(0.34,1.56,0.64,1), transform 400ms cubic-bezier(0.34,1.56,0.64,1);
}
.fullscreen-overlay.is-open .overlay-nav-item {
  opacity: 1;
  transform: translateY(0);
}
/* stagger delay */
.fullscreen-overlay.is-open .overlay-nav-item:nth-child(1) { transition-delay: 60ms; }
.fullscreen-overlay.is-open .overlay-nav-item:nth-child(2) { transition-delay: 110ms; }
.fullscreen-overlay.is-open .overlay-nav-item:nth-child(3) { transition-delay: 160ms; }
.fullscreen-overlay.is-open .overlay-nav-item:nth-child(4) { transition-delay: 210ms; }
.fullscreen-overlay.is-open .overlay-nav-item:nth-child(5) { transition-delay: 260ms; }
.fullscreen-overlay.is-open .overlay-nav-item:nth-child(6) { transition-delay: 310ms; }
.fullscreen-overlay.is-open .overlay-nav-item:nth-child(7) { transition-delay: 360ms; }

.overlay-nav-link {
  display: block;
  font-size: clamp(1.5rem, 4vw, 2.4rem);
  font-weight: 800;
  color: var(--mint);
  padding: 10px 32px;
  border-radius: var(--radius-lg);
  border: 3px solid transparent;
  letter-spacing: -0.01em;
  transition: color 200ms, border-color 200ms, background 200ms;
}
.overlay-nav-link:hover {
  color: var(--dark);
  background: var(--mint);
  border-color: var(--mint);
}

/* ===== Hero ===== */
.hero-block {
  position: relative;
  min-height: 70vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--mint) 0%, var(--blue) 100%);
  border-bottom: var(--border-thick);
  margin-top: var(--nav-h);
  overflow: hidden;
  text-align: center;
  padding: 80px 24px 120px;
}
.hero-bg-text {
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  font-size: clamp(8rem, 22vw, 18rem);
  font-weight: 800;
  color: rgba(23,38,32,0.06);
  letter-spacing: -0.05em;
  pointer-events: none;
  user-select: none;
  white-space: nowrap;
}
.hero-inner {
  position: relative;
  z-index: 1;
  max-width: 700px;
}
.hero-h1 {
  font-size: clamp(2rem, 6vw, 3.6rem);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.03em;
  color: var(--dark);
  margin-bottom: 20px;
}
.hero-sub {
  font-size: clamp(1rem, 2.5vw, 1.2rem);
  color: var(--dark-80);
  margin-bottom: 36px;
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
}
/* 圆弧底边 */
.hero-arc {
  position: absolute;
  bottom: -2px; left: 0; right: 0;
  height: 60px;
  background: var(--off-white);
  border-radius: 50% 50% 0 0 / 60px 60px 0 0;
  border-top: var(--border-thick);
}

/* ===== Clay 按钮 ===== */
.clay-btn {
  display: inline-block;
  padding: 14px 36px;
  font-family: var(--font);
  font-size: 1rem;
  font-weight: 700;
  border-radius: var(--radius-md);
  border: var(--border);
  background: var(--mint);
  color: var(--dark);
  box-shadow: var(--shadow-clay);
  transition: box-shadow 200ms ease-out, transform 200ms ease-out;
  cursor: pointer;
  min-height: 48px;
  line-height: 1.2;
}
.clay-btn:hover {
  box-shadow: var(--shadow-clay-hover);
  transform: translateY(-3px);
}
.clay-btn:active {
  box-shadow: var(--shadow-press);
  transform: translateY(1px);
}
.clay-btn--dark {
  background: var(--dark);
  color: var(--mint);
  border-color: var(--mint);
  box-shadow: 4px 4px 0 var(--mint), inset -2px -2px 8px rgba(180,253,225,0.12);
}
.clay-btn--dark:hover {
  box-shadow: 6px 6px 0 var(--mint), inset -2px -2px 8px rgba(180,253,225,0.18);
}
.clay-btn--dark:active {
  box-shadow: 2px 2px 0 var(--mint);
}

/* ===== 主内容 main > div.wrap > section > article ===== */
main { padding: 60px 0 80px; }
.wrap {
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 24px;
}
.content-section {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 40px;
  align-items: start;
}
.content-article { min-width: 0; }

/* ===== 正文内容排版 ===== */
.content-article h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 800;
  color: var(--dark);
  margin: 2.5rem 0 1rem;
  letter-spacing: -0.02em;
  line-height: 1.25;
  padding-bottom: 8px;
  border-bottom: var(--border);
}
.content-article h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--dark);
  margin: 2rem 0 0.75rem;
}
.content-article h4 {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
}
.content-article p { margin-bottom: 1rem; font-size: 1rem; line-height: 1.72; }
.content-article ul, .content-article ol {
  margin: 0.75rem 0 1rem 1.2rem;
  list-style: initial;
}
.content-article li { margin-bottom: 0.4rem; line-height: 1.65; }
.content-article strong { font-weight: 700; }
.content-article em { font-style: italic; }
.content-article a { color: var(--dark); border-bottom: 2px solid var(--mint-deep); transition: color 180ms; }
.content-article a:hover { color: var(--blue-deep); }
.content-article blockquote {
  margin: 1.5rem 0;
  padding: 16px 20px;
  border-left: 4px solid var(--mint-deep);
  background: rgba(180,253,225,0.18);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-style: italic;
}
.content-article table { width: 100%; border-collapse: collapse; margin: 1.5rem 0; font-size: 0.95rem; }
.content-article th, .content-article td {
  padding: 10px 14px;
  border: 2px solid var(--dark);
  text-align: left;
}
.content-article th { background: var(--mint); font-weight: 700; }
.content-article tr:nth-child(even) td { background: rgba(173,216,230,0.18); }

/* section 区块之间的分隔感 */
.content-article section {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 2px dashed rgba(23,38,32,0.15);
}
.content-article section:last-child { border-bottom: none; }

/* scroll-margin for nav sections */
.content-article section[id] { scroll-margin-top: 90px; }

/* ===== 侧边栏 ===== */
.content-aside {
  position: sticky;
  top: calc(var(--nav-h) + 20px);
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.aside-card {
  background: var(--mint);
  border: var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-clay);
  padding: 20px;
}
.aside-card--info {
  background: var(--blue);
}
.aside-eyebrow {
  display: block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(23,38,32,0.6);
  margin-bottom: 6px;
}
.aside-title {
  font-size: 1rem;
  font-weight: 800;
  margin-bottom: 12px;
  color: var(--dark);
}
.aside-nav-list { display: flex; flex-direction: column; gap: 6px; }
.aside-nav-link {
  display: block;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--dark);
  background: var(--white);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--dark);
  box-shadow: 2px 2px 0 var(--dark);
  transition: box-shadow 200ms ease-out, transform 200ms ease-out, background 180ms;
  min-height: 40px;
  display: flex;
  align-items: center;
}
.aside-nav-link:hover {
  background: var(--mint);
  box-shadow: 3px 3px 0 var(--dark);
  transform: translateY(-1px);
}
.aside-desc {
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--dark-80);
}

/* ===== h2 前 small 眉题（正文注入） ===== */
small.aside-eyebrow,
small.footer-eyebrow,
small.footer-info-eyebrow {
  display: block;
}

/* ===== 页脚 CTA 块 ===== */
.footer-cta-block {
  background: linear-gradient(135deg, var(--mint) 0%, var(--blue) 100%);
  border-top: var(--border-thick);
  border-bottom: var(--border-thick);
  padding: 60px 24px;
  text-align: center;
}
.footer-eyebrow {
  display: block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(23,38,32,0.55);
  margin-bottom: 10px;
}
.footer-cta-title {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 800;
  color: var(--dark);
  margin-bottom: 28px;
  letter-spacing: -0.02em;
}

/* ===== 页脚主体 footer 结构 ===== */
.site-footer {
  background: var(--dark);
  color: var(--mint);
  border-top: var(--border-thick);
}
.footer-main {
  max-width: 1140px;
  margin: 0 auto;
  padding: 48px 24px;
  display: grid;
  grid-template-columns: 2fr 1.5fr 1fr 1fr;
  gap: 40px;
  align-items: start;
}
.footer-brand-col {}
.footer-brand-link .logo-text { color: var(--mint); }
.footer-brand-link .site-logo-img { filter: brightness(0) invert(1); }
.footer-brand-desc {
  margin-top: 14px;
  font-size: 0.88rem;
  line-height: 1.6;
  color: rgba(180,253,225,0.7);
  max-width: 260px;
}

/* footer nav > dl > dt/dd > a */
.footer-nav-wrap {}
.footer-nav-dl {}
.footer-nav-dt {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(180,253,225,0.5);
  margin-bottom: 14px;
}
.footer-nav-dl dd { margin: 0; }
.footer-nav-dl dd a {
  display: block;
  padding: 7px 0;
  font-size: 0.92rem;
  font-weight: 500;
  color: rgba(180,253,225,0.85);
  border-bottom: 1px solid rgba(180,253,225,0.1);
  transition: color 180ms, padding-left 180ms;
  min-height: 40px;
  display: flex;
  align-items: center;
}
.footer-nav-dl dd a:hover { color: var(--mint); padding-left: 6px; }

.footer-info-col {}
.footer-info-eyebrow {
  display: block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(180,253,225,0.5);
  margin-bottom: 14px;
}
.footer-contact {
  font-size: 0.9rem;
  color: rgba(180,253,225,0.85);
  margin-bottom: 8px;
}
.footer-contact-link { border-bottom: 1px solid rgba(180,253,225,0.4); transition: color 180ms; }
.footer-contact-link:hover { color: var(--mint); }
.footer-contact-empty { font-size: 0.85rem; color: rgba(180,253,225,0.45); }

.footer-meta-col {}
.footer-keyword {
  font-size: 0.88rem;
  color: rgba(180,253,225,0.6);
  line-height: 1.6;
}

/* 页脚底栏 */
.footer-bottom {
  max-width: 1140px;
  margin: 0 auto;
  padding: 16px 24px;
  border-top: 1px solid rgba(180,253,225,0.15);
}
.footer-copy {
  font-size: 0.82rem;
  color: rgba(180,253,225,0.45);
}

/* ===== 入场动画 stagger ===== */
.stagger-item {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 500ms cubic-bezier(0.34,1.56,0.64,1), transform 500ms cubic-bezier(0.34,1.56,0.64,1);
}
.stagger-item.in-view { opacity: 1; transform: translateY(0); }

/* ===== 正文内 section 样式补强（claymorphism 感） ===== */
.content-article section {
  background: var(--white);
  border: var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-clay);
  padding: 28px 28px 24px;
  margin-bottom: 28px;
  transition: box-shadow 200ms ease-out, transform 200ms ease-out;
}
.content-article section:hover {
  box-shadow: var(--shadow-clay-hover);
  transform: translateY(-2px);
}
.content-article section:last-child { border-bottom: var(--border); }
.content-article section h2:first-child { margin-top: 0; }

/* ===== 卡片（纯色块无边框，圆角0，站群规格） ===== */
.card {
  background: var(--mint);
  border-radius: 0;
  padding: 24px;
  border: none;
}
.card--blue { background: var(--blue); }

/* ===== 移动端响应式 ===== */
@media (max-width: 900px) {
  .content-section {
    grid-template-columns: 1fr;
  }
  .content-aside {
    position: static;
  }
  .footer-main {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }
}

@media (max-width: 600px) {
  :root { --nav-h: 64px; }
  .top-brand-bar { padding: 0 16px; }
  .wrap { padding: 0 16px; }
  .hero-block { padding: 60px 16px 100px; min-height: 70vh; }
  .hero-h1 { font-size: 1.9rem; }
  .footer-main {
    grid-template-columns: 1fr;
    gap: 28px;
    padding: 36px 16px;
  }
  .footer-cta-block { padding: 44px 16px; }
  .content-article section { padding: 20px 16px; }
  main { padding: 40px 0 60px; }
  .overlay-nav-link { font-size: 1.5rem; padding: 10px 20px; }
}

/* ===== prefers-reduced-motion ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
  }
  html { scroll-behavior: auto; }
  .stagger-item { opacity: 1 !important; transform: none !important; }
  .overlay-nav-item { opacity: 1 !important; transform: none !important; }
}