:root {
  --color-bg-page: #f3f7f6;
  --color-bg-card: #ffffff;
  --color-bg-rail: #f7f4ee;
  --color-theme: #14968f;
  --color-copper: #c48a3a;
  --color-text: #1c3338;
  --color-muted: #7a9298;
  --color-border: rgba(20, 150, 143, 0.22);
  --ease-smooth: cubic-bezier(0.22, 1, 0.36, 1);
  --font-serif: "Songti SC", "Noto Serif SC", "STSong", "SimSun", serif;
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --space-xs: 0.5rem;
  --space-sm: 0.75rem;
  --space-md: 1.25rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --text-sm: clamp(0.8125rem, 2.5vw, 0.9375rem);
  --text-base: clamp(0.9375rem, 2.8vw, 1.0625rem);
  --text-lg: clamp(1.125rem, 3.2vw, 1.375rem);
  --text-xl: clamp(1.375rem, 4vw, 1.75rem);
  --rail-width: min(100%, 100vw);
  --content-max: 72rem;
  --draw-offset: 100;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg-page);
  overflow-x: hidden;
}

img,
svg {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--color-theme);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}

a:hover {
  color: var(--color-copper);
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* 侧轨 / 页眉 */
.rail {
  background: var(--color-bg-rail);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 20;
}

.rail-inner {
  padding: var(--space-sm) var(--space-md);
  max-width: 100%;
}

.brand {
  margin: 0 0 var(--space-xs);
  font-family: var(--font-serif);
  font-size: var(--text-sm);
  line-height: 1.4;
  color: var(--color-text);
}

.tagline {
  margin: 0 0 var(--space-sm);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--color-copper);
  line-height: 1.35;
}

.nav-toggle {
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  padding: 0.5rem 0.85rem;
  border: 1px solid var(--color-muted);
  background: transparent;
  color: var(--color-text);
  cursor: pointer;
  min-height: 2.75rem;
}

.nav-toggle:hover {
  border-color: var(--color-theme);
}

.site-nav {
  display: none;
  flex-direction: column;
  gap: var(--space-xs);
  padding: var(--space-sm) 0 0;
}

.site-nav.is-open {
  display: flex;
}

.site-nav a {
  position: relative;
  display: block;
  padding: 0.55rem 0 0.55rem var(--space-md);
  color: var(--color-text);
  text-decoration: none;
  min-height: 2.75rem;
  line-height: 1.6;
}

.site-nav a::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 0;
  height: 2px;
  background: var(--color-theme);
  transform: translateY(-50%);
  transition: width 0.5s var(--ease-smooth);
}

.site-nav a:hover::before,
.site-nav a:focus-visible::before,
.site-nav a.is-current::before {
  width: 1.1rem;
}

.site-nav a.is-current {
  color: var(--color-theme);
  font-weight: 600;
}

.content {
  flex: 1;
  min-width: 0;
  width: 100%;
}

#shouping,
#about,
#services,
#advantages {
  scroll-margin-top: 9rem;
}

/* 首屏 */
.hero {
  padding: var(--space-md);
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.hero-copy {
  order: 1;
}

.hero-highlight {
  margin: 0 0 var(--space-sm);
  font-family: var(--font-serif);
  font-size: var(--text-xl);
  line-height: 1.35;
  color: var(--color-text);
}

.hero-sub {
  margin: 0;
  color: var(--color-text);
  max-width: 38em;
}

.hero-visual {
  order: 0;
  width: 100%;
  border: 1px solid var(--color-border);
  background: var(--color-bg-card);
}

.hero-svg {
  width: 100%;
  aspect-ratio: 800 / 520;
}

.hero-draw-line {
  stroke-dasharray: var(--draw-offset);
  stroke-dashoffset: var(--draw-offset);
}

.hero-svg.is-hero-ready .hero-draw-line {
  stroke-dashoffset: 0;
  transition: stroke-dashoffset 1.4s var(--ease-smooth);
}

.hero-svg.is-hero-ready .hero-draw-line:nth-child(2) {
  transition-delay: 0.12s;
}

.hero-svg.is-hero-ready .hero-draw-line:nth-child(3) {
  transition-delay: 0.24s;
}

.hero-svg.is-hero-ready .hero-draw-line:nth-child(4) {
  transition-delay: 0.36s;
}

.hero-node {
  opacity: 0;
  transform-origin: center;
  transform-box: fill-box;
  transform: scale(0.88);
}

.hero-svg.is-hero-ready .hero-node {
  opacity: 1;
  transform: scale(1);
  transition: opacity 0.55s var(--ease-smooth), transform 0.55s var(--ease-smooth);
}

.hero-svg.is-hero-ready .hero-node:nth-child(1) {
  transition-delay: 1.45s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(2) {
  transition-delay: 1.55s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(3) {
  transition-delay: 1.65s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(4) {
  transition-delay: 1.75s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(5) {
  transition-delay: 1.85s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(6) {
  transition-delay: 1.95s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(7) {
  transition-delay: 2.05s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(8) {
  transition-delay: 2.15s;
}

.hero-svg.is-hero-ready .hero-node:nth-child(9) {
  transition-delay: 2.25s;
}

.hero-node--pulse {
  animation: none;
}

.hero-svg.is-hero-ready .hero-node--pulse {
  animation: node-pulse-slow 5.5s var(--ease-smooth) infinite;
  animation-delay: 2.5s;
}

@keyframes node-pulse-slow {
  0%,
  100% {
    opacity: 0.82;
    transform: scale(1);
  }
  50% {
    opacity: 1;
    transform: scale(1.04);
  }
}

.link-stages {
  order: 2;
  margin: 0 calc(-1 * var(--space-md));
  padding: 0 var(--space-md);
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
}

.link-stages-track {
  display: flex;
  gap: var(--space-sm);
  width: max-content;
  padding-bottom: var(--space-xs);
}

.stage-chip {
  flex: 0 0 auto;
  padding: 0.5rem 0.85rem;
  border: 1px solid var(--color-border);
  color: var(--color-text);
  text-decoration: none;
  font-size: var(--text-sm);
  white-space: nowrap;
  background: var(--color-bg-card);
}

.stage-chip:hover {
  border-color: var(--color-theme);
  color: var(--color-theme);
}

/* 关于我们 */
.about {
  padding: var(--space-xl) var(--space-md);
  border-top: 1px solid var(--color-border);
}

.about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-md);
  max-width: var(--content-max);
  margin-inline: auto;
  width: 100%;
}

.about-accent {
  width: 2px;
  min-height: 6rem;
  background: linear-gradient(180deg, var(--color-theme), transparent);
  justify-self: start;
  transform: scaleY(0);
  transform-origin: top center;
}

.about.is-visible .about-accent {
  transform: scaleY(1);
  transition: transform 1s var(--ease-smooth);
}

.about-body h2 {
  margin: 0 0 var(--space-md);
  font-family: var(--font-serif);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--color-theme);
}

.about-text {
  opacity: 0;
  transform: translateY(0.35rem);
}

.about.is-visible .about-text {
  opacity: 1;
  transform: none;
  transition: opacity 0.75s var(--ease-smooth) 0.35s, transform 0.75s var(--ease-smooth) 0.35s;
}

.about-text p {
  margin: 0;
  max-width: 36em;
  text-align: left;
}

/* 核心业务 */
.services {
  padding: var(--space-xl) var(--space-md);
  border-top: 1px solid var(--color-border);
}

.services h2 {
  margin: 0 auto var(--space-lg);
  font-family: var(--font-serif);
  font-size: var(--text-lg);
  color: var(--color-theme);
  max-width: var(--content-max);
  width: 100%;
}

.services-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  max-width: var(--content-max);
  margin-inline: auto;
  width: 100%;
}

.service-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  padding: var(--space-md);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.85s var(--ease-smooth), transform 0.85s var(--ease-smooth);
}

.service-card.is-drawn {
  opacity: 1;
  transform: translateY(0);
  transition-delay: var(--card-delay, 0s);
}

.service-graphic {
  width: 100%;
  overflow: hidden;
}

.topology-svg {
  width: 100%;
  aspect-ratio: 400 / 220;
}

.service-card--small .topology-svg {
  aspect-ratio: 320 / 180;
}

.draw-line {
  stroke-dasharray: var(--draw-offset);
  stroke-dashoffset: var(--draw-offset);
}

.service-card.is-drawn .draw-line {
  stroke-dashoffset: 0;
  transition: stroke-dashoffset 1.15s var(--ease-smooth) 0.08s;
}

.service-card.is-drawn .draw-line:nth-child(2) {
  transition-delay: 0.22s;
}

.service-card h3 {
  margin: 0;
  font-size: var(--text-lg);
  font-weight: 600;
}

.service-hook {
  margin: 0;
  color: var(--color-copper);
  font-size: var(--text-sm);
}

.service-desc {
  margin: 0;
  color: var(--color-text);
  font-size: var(--text-sm);
}

/* 核心优势 */
.advantages {
  padding: var(--space-xl) var(--space-md);
  border-top: 1px solid var(--color-border);
  max-width: 100%;
}

.advantages h2 {
  margin: 0 auto var(--space-lg);
  font-family: var(--font-serif);
  font-size: var(--text-lg);
  color: var(--color-theme);
  max-width: var(--content-max);
  width: 100%;
}

.advantage-list {
  list-style: none;
  margin: 0 auto;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  max-width: var(--content-max);
  width: 100%;
}

.advantage-item {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  overflow: hidden;
}

.advantage-index {
  display: flex;
  align-items: stretch;
  justify-content: center;
  padding: var(--space-md) var(--space-sm);
  min-width: 3.25rem;
  background: var(--color-theme);
  color: #ffffff;
  font-weight: 700;
  font-size: var(--text-sm);
  writing-mode: horizontal-tb;
  transform: scaleX(0);
  transform-origin: left center;
}

.advantage-item.is-visible .advantage-index {
  transform: scaleX(1);
  transition: transform 0.75s var(--ease-smooth);
  transition-delay: var(--adv-delay, 0s);
}

.advantage-content {
  padding: var(--space-md);
  min-width: 0;
  opacity: 0;
}

.advantage-item.is-visible .advantage-content {
  opacity: 1;
  transition: opacity 0.7s var(--ease-smooth);
  transition-delay: calc(var(--adv-delay, 0s) + 0.18s);
}

.advantage-content h3 {
  margin: 0 0 var(--space-xs);
  font-size: var(--text-base);
  font-weight: 600;
}

.advantage-content p {
  margin: 0;
  font-size: var(--text-sm);
  color: var(--color-text);
}

/* 页脚 */
.site-footer {
  padding: var(--space-md);
  text-align: center;
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-page);
  font-size: var(--text-sm);
}

.site-footer p {
  margin: 0 0 var(--space-xs);
  color: var(--color-text);
}

.site-footer a {
  color: var(--color-muted);
}

/* 偏高竖屏 */
@media (max-aspect-ratio: 3/4) {
  .hero {
    padding-top: var(--space-sm);
  }

  .about {
    padding-block: var(--space-lg);
  }
}

/* 手机横屏矮屏 */
@media (orientation: landscape) and (max-height: 500px) {
  .rail {
    position: relative;
  }

  .hero {
    padding: var(--space-sm) var(--space-md);
    flex-direction: row;
    flex-wrap: wrap;
    align-items: flex-start;
  }

  .hero-visual {
    order: 2;
    flex: 1 1 45%;
    max-height: 42vh;
  }

  .hero-svg {
    max-height: 42vh;
    width: 100%;
    object-fit: contain;
  }

  .hero-copy {
    order: 1;
    flex: 1 1 50%;
  }

  .hero-highlight {
    font-size: var(--text-lg);
  }

  .link-stages {
    order: 3;
    flex: 1 1 100%;
    margin-top: 0;
  }

  .site-nav.is-open {
    flex-direction: row;
    flex-wrap: wrap;
    gap: var(--space-sm);
  }

  .site-nav a {
    padding-left: var(--space-md);
    min-height: auto;
  }
}

/* 平板 */
@media (min-width: 768px) {
  .link-stages {
    display: none;
  }

  .about-layout {
    grid-template-columns: 3rem minmax(0, 1fr);
    align-items: start;
  }

  .about-text p {
    text-align: left;
  }

  .services-grid {
    display: grid;
    grid-template-columns: repeat(5, minmax(0, 1fr));
    grid-template-rows: auto auto;
    gap: var(--space-md);
  }

  #service-integration {
    grid-column: 1 / span 3;
    grid-row: 1;
  }

  #service-software {
    grid-column: 4 / span 2;
    grid-row: 1;
  }

  #service-5g {
    grid-column: 1 / span 2;
    grid-row: 2;
  }

  #service-security {
    grid-column: 3 / span 3;
    grid-row: 2;
  }

  .service-card--large {
    min-height: 18rem;
  }

  .service-card--small {
    min-height: 14rem;
    margin-top: 2rem;
  }
}

/* 桌面：左轨固定 */
@media (min-width: 1100px) {
  .app {
    flex-direction: row;
    align-items: stretch;
  }

  .rail {
    position: fixed;
    left: 0;
    top: 0;
    width: clamp(15rem, 22vw, 20rem);
    height: 100vh;
    border-bottom: none;
    border-right: 1px solid var(--color-border);
    overflow-y: auto;
  }

  .rail-inner {
    padding: var(--space-lg) var(--space-md);
    display: flex;
    flex-direction: column;
    min-height: 100%;
  }

  .tagline {
    font-size: var(--text-xl);
    margin-bottom: var(--space-lg);
  }

  .nav-toggle {
    display: none;
  }

  .site-nav {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
    padding-top: var(--space-md);
    margin-top: auto;
  }

  .content {
    margin-left: clamp(15rem, 22vw, 20rem);
    width: calc(100% - clamp(15rem, 22vw, 20rem));
  }

  #shouping,
  #about,
  #services,
  #advantages {
    scroll-margin-top: 1rem;
  }

  .hero {
    padding: var(--space-xl) var(--space-lg);
    min-height: min(85vh, 40rem);
    display: grid;
    grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
    gap: var(--space-lg);
    align-items: center;
  }

  .hero-copy {
    order: 1;
  }

  .hero-visual {
    order: 2;
    flex: unset;
  }

  .about,
  .services,
  .advantages {
    padding-inline: var(--space-lg);
  }

}

/* 宽屏 */
@media (min-width: 1440px) {
  .content {
    padding-inline: clamp(1rem, 4vw, 3rem);
  }

  .hero {
    width: 100%;
    max-width: none;
  }
}

/* 超宽 */
@media (min-aspect-ratio: 2/1) {
  .hero {
    flex-direction: row;
    align-items: center;
    gap: var(--space-xl);
  }

  .hero-copy {
    flex: 0 1 32%;
  }

  .hero-visual {
    flex: 1 1 60%;
  }

  .advantage-content p {
    max-width: 48em;
  }
}

@media (prefers-reduced-motion: reduce) {
  .hero-node,
  .hero-node--pulse {
    animation: none;
    opacity: 1;
    transform: none;
  }

  .hero-svg.is-hero-ready .hero-draw-line,
  .hero-svg.is-hero-ready .hero-node {
    transition: none;
  }

  .hero-draw-line {
    stroke-dashoffset: 0;
  }

  .about-accent {
    transform: scaleY(1);
  }

  .about-text,
  .about.is-visible .about-text {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .service-card,
  .service-card.is-drawn {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .draw-line,
  .service-card.is-drawn .draw-line {
    stroke-dashoffset: 0;
    transition: none;
  }

  .advantage-index,
  .advantage-item.is-visible .advantage-index {
    transform: scaleX(1);
    transition: none;
  }

  .advantage-content,
  .advantage-item.is-visible .advantage-content {
    opacity: 1;
    transition: none;
  }

  .site-nav a::before {
    transition: none;
  }
}