:root {
  --color-bg: #F7F2EA;
  --color-text: #1E2428;
  --color-accent: #C8843A;
  --color-border: #E8D5BC;
  --color-footer: #141A1F;
  --font-serif: "Songti SC", "Noto Serif SC", "STSong", "SimSun", serif;
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --max-width: 1080px;
  --content-max: var(--max-width);
  --layout-gutter: var(--space-md);
  --rail-width: 3px;
  --rail-offset: 1.25rem;
  --header-h: 3.25rem;
  --scroll-gap: 0.875rem;
  --scroll-margin: calc(var(--header-h) + var(--scroll-gap));
  --space-xs: 0.5rem;
  --space-sm: 0.875rem;
  --space-md: 1.25rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --text-sm: 0.9375rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.375rem;
  --text-2xl: 1.75rem;
  --text-hero: clamp(1.625rem, 4.5vw, 2.125rem);
  --reveal-duration: 0.65s;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--scroll-margin);
  overflow-x: hidden;
}

#home,
#about,
#services,
#advantages {
  scroll-margin-top: var(--scroll-margin);
}

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);
  overflow-x: hidden;
}

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

a {
  color: inherit;
}

.page-main {
  position: relative;
  padding-top: var(--header-h);
}

.path-rail {
  position: fixed;
  left: calc(var(--layout-gutter) + var(--rail-offset));
  top: calc(var(--header-h) + 1rem);
  bottom: 1rem;
  width: var(--rail-width);
  background: linear-gradient(to bottom, transparent, var(--color-border) 8%, var(--color-accent) 45%, var(--color-border) 92%, transparent);
  opacity: 0.85;
  pointer-events: none;
  z-index: 0;
}

/* 页眉 */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-h);
  background: color-mix(in srgb, var(--color-bg) 92%, transparent);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(6px);
}

.header-inner {
  position: relative;
  max-width: var(--content-max);
  margin: 0 auto;
  padding-left: var(--space-md);
  padding-right: var(--space-md);
  height: 100%;
  display: flex;
  flex-wrap: nowrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
  min-width: 0;
}

.logo {
  flex-shrink: 0;
  font-family: var(--font-serif);
  font-size: var(--text-lg);
  font-weight: 600;
  text-decoration: none;
  letter-spacing: 0.06em;
  border-bottom: 2px solid transparent;
  transition: border-color 0.25s ease;
}

.logo:hover,
.logo:focus-visible {
  border-bottom-color: var(--color-accent);
  outline: none;
}

.nav-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 2.75rem;
  min-height: 2.75rem;
  padding: 0 var(--space-sm);
  font-family: inherit;
  font-size: var(--text-sm);
  color: var(--color-text);
  background: transparent;
  border: 1px solid var(--color-border);
  cursor: pointer;
}

.site-nav {
  flex-shrink: 1;
  min-width: 0;
}

.site-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: nowrap;
  gap: var(--space-sm) var(--space-md);
  justify-content: flex-end;
}

.site-nav a {
  text-decoration: none;
  font-size: var(--text-sm);
  padding: 0.35rem 0;
  border-bottom: 2px solid transparent;
  transition: border-color 0.25s ease;
}

.site-nav a:hover,
.site-nav a:focus-visible {
  border-bottom-color: var(--color-accent);
  outline: none;
}

.site-nav:not(.is-open) {
  display: none;
}

.site-nav.is-open {
  display: block;
  position: fixed;
  top: var(--header-h);
  left: 0;
  right: 0;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-md);
  z-index: 99;
}

.site-nav.is-open ul {
  flex-direction: column;
}

.site-nav.is-open a {
  display: block;
  padding: 0.5rem 0;
}

/* 首屏 */
.hero {
  position: relative;
  z-index: 1;
  padding: var(--space-lg) var(--space-md) var(--space-xl);
}

.hero-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding-left: calc(var(--rail-offset) + var(--rail-width) + var(--space-sm));
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
}

.hero-copy h1 {
  font-family: var(--font-serif);
  font-size: var(--text-hero);
  font-weight: 600;
  line-height: 1.35;
  margin: 0 0 var(--space-md);
  max-width: 16em;
}

.hero-sub {
  margin: 0 0 var(--space-sm);
  max-width: 28em;
  font-size: var(--text-lg);
}

.hero-highlight {
  margin: 0 0 var(--space-lg);
  padding-left: var(--space-sm);
  border-left: 3px solid var(--color-accent);
  font-family: var(--font-serif);
  font-size: var(--text-lg);
  max-width: 22em;
}

.btn-anchor {
  display: inline-block;
  padding: 0.65rem 1.25rem;
  font-size: var(--text-sm);
  text-decoration: none;
  color: var(--color-text);
  border: 1px solid var(--color-accent);
  background: color-mix(in srgb, var(--color-bg) 80%, var(--color-border));
  transition: border-color 0.25s ease, box-shadow 0.25s ease;
}

.btn-anchor:hover,
.btn-anchor:focus-visible {
  border-color: var(--color-text);
  box-shadow: inset 3px 0 0 var(--color-accent);
  outline: none;
}

.hero-steps {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  align-items: flex-start;
}

.steps-visual {
  overflow: hidden;
  max-height: 12rem;
}

.light-steps-img {
  animation: light-drift 18s ease-in-out infinite alternate;
  transform-origin: center top;
}

@keyframes light-drift {
  from {
    transform: translateY(0);
  }
  to {
    transform: translateY(-14px);
  }
}

.steps-results {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  width: 100%;
  max-width: 22rem;
}

.steps-results li {
  position: relative;
  padding: var(--space-sm) var(--space-sm) var(--space-sm) var(--space-md);
  border-left: 2px solid var(--color-border);
  font-size: var(--text-sm);
  transition: border-color 0.25s ease;
}

.steps-results li:nth-child(1) {
  margin-left: 0;
}

.steps-results li:nth-child(2) {
  margin-left: 0.75rem;
}

.steps-results li:nth-child(3) {
  margin-left: 1.5rem;
}

.steps-results li:hover {
  border-left-color: var(--color-accent);
}

/* 关于我们 */
.about {
  position: relative;
  z-index: 1;
  background: color-mix(in srgb, var(--color-border) 35%, var(--color-bg));
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-xl) var(--space-md);
}

.about-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding-left: calc(var(--rail-offset) + var(--rail-width) + var(--space-sm));
  display: grid;
  grid-template-columns: minmax(2.5rem, 18%) 1fr;
  gap: var(--space-md);
}

.section-index {
  font-family: var(--font-serif);
  font-size: var(--text-sm);
  letter-spacing: 0.2em;
  color: var(--color-accent);
  writing-mode: vertical-rl;
  text-orientation: mixed;
}

.about-content {
  max-width: 42rem;
  margin-left: auto;
  width: 100%;
}

.about-content h2 {
  font-family: var(--font-serif);
  font-size: var(--text-xl);
  margin: 0 0 var(--space-md);
  font-weight: 600;
}

.about-text p {
  margin: 0;
  text-align: justify;
  hyphens: auto;
}

/* 核心业务 */
.services {
  position: relative;
  z-index: 1;
  padding: var(--space-xl) var(--space-md);
}

.services-head {
  max-width: var(--content-max);
  margin: 0 auto var(--space-lg);
  padding-left: calc(var(--rail-offset) + var(--rail-width) + var(--space-sm));
}

.services-head h2 {
  font-family: var(--font-serif);
  font-size: var(--text-xl);
  margin: 0;
  font-weight: 600;
}

.service-strip {
  max-width: var(--content-max);
  margin: 0 auto var(--space-lg);
  padding-left: calc(var(--rail-offset) + var(--rail-width) + var(--space-sm));
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--color-border);
}

.strip-body {
  flex: 1 1 58%;
  min-width: 0;
}

.strip-num {
  display: block;
  font-family: var(--font-serif);
  font-size: var(--text-2xl);
  color: var(--color-accent);
  line-height: 1;
  margin-bottom: var(--space-sm);
  opacity: 0.9;
}

.strip-body h3 {
  font-family: var(--font-serif);
  font-size: var(--text-xl);
  margin: 0 0 var(--space-xs);
  font-weight: 600;
}

.strip-hook {
  margin: 0 0 var(--space-sm);
  font-size: var(--text-lg);
  color: color-mix(in srgb, var(--color-text) 88%, var(--color-accent));
}

.strip-text {
  margin: 0;
  font-size: var(--text-sm);
  max-width: 36em;
}

.strip-deco {
  flex: 1 1 42%;
  min-height: 5.5rem;
  max-height: 9rem;
  align-self: stretch;
  background-color: color-mix(in srgb, var(--color-border) 22%, var(--color-bg));
  background-image: url("strip-deco.svg");
  background-repeat: no-repeat;
  background-position: center;
  background-size: min(100%, 14rem) auto;
  border-left: 1px solid var(--color-border);
}

.strip-left .strip-deco {
  background-position: 55% center;
}

.strip-right .strip-deco {
  border-left: none;
  border-right: 1px solid var(--color-border);
  transform: scaleX(-1);
  background-position: 45% center;
}

/* 核心优势 */
.advantages {
  position: relative;
  z-index: 1;
  padding: var(--space-xl) var(--space-md);
}

.advantages-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding-left: calc(var(--rail-offset) + var(--rail-width) + var(--space-sm));
}

.advantages-inner h2 {
  font-family: var(--font-serif);
  font-size: var(--text-xl);
  margin: 0 0 var(--space-lg);
  font-weight: 600;
}

.advantages-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

.adv-block {
  padding: var(--space-md) var(--space-md) var(--space-md) var(--space-lg);
  border-left: 4px solid var(--color-accent);
  background: color-mix(in srgb, var(--color-bg) 70%, var(--color-border));
  transition: border-left-width 0.25s ease;
}

.adv-block:hover {
  border-left-width: 6px;
}

.adv-block h3 {
  font-family: var(--font-serif);
  font-size: var(--text-lg);
  margin: 0 0 var(--space-xs);
  font-weight: 600;
}

.adv-block p {
  margin: 0;
  font-size: var(--text-sm);
}

/* 页脚 */
.site-footer {
  background: var(--color-footer);
  color: color-mix(in srgb, var(--color-bg) 88%, white);
  text-align: center;
  padding: var(--space-lg) var(--space-md);
  font-size: var(--text-sm);
}

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

.footer-beian {
  margin-bottom: 0 !important;
}

.site-footer a {
  color: inherit;
  text-decoration: underline;
  text-underline-offset: 0.2em;
}

.site-footer a:hover,
.site-footer a:focus-visible {
  color: var(--color-border);
  outline: none;
}

/* 入场动效 */
.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity var(--reveal-duration) ease, transform var(--reveal-duration) ease;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 767px) {
  .service-strip .strip-body {
    order: 1;
  }

  .service-strip .strip-deco {
    order: 2;
    width: 100%;
    flex: 0 0 auto;
    min-height: 3rem;
    max-height: 4rem;
  }
}

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

  .site-nav:not(.is-open),
  .site-nav.is-open {
    display: block;
    position: static;
    top: auto;
    left: auto;
    right: auto;
    padding: 0;
    background: transparent;
    border: none;
    z-index: auto;
  }

  .site-nav:not(.is-open) ul,
  .site-nav.is-open ul {
    flex-direction: row;
  }

  .site-nav:not(.is-open) a,
  .site-nav.is-open a {
    display: inline;
    padding: 0.35rem 0;
  }

  .hero-inner {
    flex-direction: row;
    align-items: flex-start;
    justify-content: space-between;
  }

  .hero-copy {
    flex: 0 1 58%;
    min-width: 0;
  }

  .hero-steps {
    flex: 0 1 42%;
    min-width: 0;
    align-items: flex-end;
  }

  .steps-results {
    align-self: stretch;
  }

  .service-strip {
    flex-direction: row;
    align-items: stretch;
  }

  .advantages-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-lg) var(--space-md);
  }

  .adv-offset-b {
    margin-top: 1.5rem;
  }

  .adv-offset-c {
    margin-top: -0.5rem;
  }

  .adv-offset-d {
    margin-top: 1rem;
  }
}

/* 桌面 */
@media (min-width: 1100px) {
  :root {
    --header-h: 3.5rem;
  }

  .hero {
    padding-top: var(--space-xl);
  }

  .about-content {
    max-width: 46rem;
  }
}

/* 宽屏 */
@media (min-width: 1440px) {
  :root {
    --layout-gutter: max(var(--space-md), calc((100vw - var(--content-max)) / 2));
  }

  .path-rail {
    left: var(--layout-gutter);
  }

  body {
    font-size: 1.0625rem;
  }
}

/* 手机横屏矮屏 */
@media (orientation: landscape) and (max-height: 500px) {
  :root {
    --header-h: 2.75rem;
    --scroll-gap: 0.5rem;
  }

  .hero {
    padding-top: var(--space-sm);
    padding-bottom: var(--space-md);
  }

  .hero-inner {
    flex-direction: column;
    gap: var(--space-sm);
  }

  .hero-copy {
    flex: none;
    width: 100%;
    min-width: min(100%, 36rem);
    max-width: 100%;
  }

  .hero-copy h1 {
    font-size: clamp(1.125rem, 2.8vw, 1.375rem);
    margin-bottom: var(--space-xs);
    max-width: none;
    line-height: 1.25;
    white-space: nowrap;
  }

  .hero-sub,
  .hero-highlight {
    font-size: var(--text-sm);
    margin-bottom: var(--space-xs);
    max-width: none;
  }

  .hero-highlight {
    white-space: nowrap;
  }

  .hero-steps {
    flex: none;
    width: 100%;
    max-width: 100%;
    flex-direction: row;
    align-items: flex-end;
    gap: var(--space-sm);
    min-width: 0;
  }

  .steps-visual {
    flex: 0 0 auto;
    max-height: 4.5rem;
  }

  .light-steps-img {
    width: 64px;
    height: auto;
  }

  .steps-results {
    flex: 1 1 auto;
    min-width: 12em;
    max-width: none;
    gap: 0.25rem;
  }

  .steps-results li {
    padding: 0.2rem 0 0.2rem var(--space-sm);
    font-size: 0.8125rem;
    line-height: 1.3;
    white-space: nowrap;
    margin-left: 0 !important;
  }

  .strip-deco {
    min-height: 3.25rem;
    max-height: 4.5rem;
    background-size: min(100%, 11rem) auto;
  }
}

/* 超宽（仅桌面宽屏，排除手机横屏） */
@media (min-aspect-ratio: 2/1) and (min-width: 1440px) {
  :root {
    --content-max: min(920px, 42vw);
    --layout-gutter: max(calc((100vw - var(--content-max)) / 2), 6vw);
  }

  .path-rail {
    left: var(--layout-gutter);
  }
}

/* 偏高竖屏 */
@media (max-aspect-ratio: 3/4) {
  .hero-highlight {
    font-size: var(--text-base);
  }

  .path-rail {
    opacity: 0.65;
  }

  .adv-block {
    padding-top: var(--space-sm);
    padding-bottom: var(--space-sm);
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .light-steps-img {
    animation: none;
  }
}