/* 基础 Design System */
:root {
  --color-primary: #3b59aa;
  --color-primary-dark: #304887;
  --color-primary-light: #eef2fb;
  --color-accent: #e60000;
  --color-text: #1f2937;
  --color-text-secondary: #5b6472;
  --color-border: #dfe3e8;
  --color-bg: #ffffff;
  --color-bg-secondary: #f5f7f9;
  --color-white: #ffffff;

  --font-family-base:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", "Noto Sans SC", Arial, sans-serif;
  --font-size-body: 1rem;
  --line-height-body: 1.7;
  --font-weight-heading: 700;

  --container-max-width: 76rem;
  --container-padding: clamp(1.25rem, 3vw, 2rem);
  --header-height: 5rem;
  --radius-small: 0.25rem;
  --transition-fast: 160ms ease;
}

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

html {
  color-scheme: light;
  scroll-behavior: auto;
}

body {
  margin: 0;
  color: var(--color-text);
  background: var(--color-bg);
  font-family: var(--font-family-base);
  font-size: var(--font-size-body);
  line-height: var(--line-height-body);
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  color: var(--color-text);
  font-weight: var(--font-weight-heading);
  line-height: 1.3;
}

a {
  color: var(--color-primary-dark);
  text-underline-offset: 0.18em;
}

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

:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 3px;
}

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

.container {
  width: calc(100% - (2 * var(--container-padding)));
  max-width: var(--container-max-width);
  margin-inline: auto;
}

section {
  padding-block: 3rem;
}

main section[id] {
  scroll-margin-top: calc(var(--header-height) + 1rem);
}

/* Hero 首屏 */
.hero {
  padding-block: clamp(3.5rem, 7vw, 6rem);
  background: var(--color-bg-secondary);
}

.hero__inner {
  display: grid;
  grid-template-columns: minmax(0, 1.04fr) minmax(0, 0.96fr);
  align-items: center;
  gap: clamp(2.5rem, 5vw, 5rem);
}

.hero__content {
  max-width: 39rem;
}

.hero__eyebrow {
  display: flex;
  margin: 0 0 1rem;
  align-items: center;
  gap: 0.75rem;
  color: var(--color-primary);
  font-size: 0.875rem;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.hero__eyebrow::before {
  width: 1.75rem;
  height: 2px;
  flex: 0 0 auto;
  background: var(--color-accent);
  content: "";
}

.hero h1 {
  max-width: 11em;
  margin: 0;
  font-size: clamp(2.125rem, 4.25vw, 3.5rem);
  letter-spacing: -0.025em;
  line-height: 1.18;
  text-wrap: balance;
}

.hero__description {
  max-width: 38em;
  margin: clamp(1.25rem, 2.5vw, 1.75rem) 0 0;
  color: var(--color-text-secondary);
  font-size: clamp(1rem, 1.25vw, 1.125rem);
  line-height: 1.85;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.875rem;
  margin-top: clamp(1.75rem, 3vw, 2.25rem);
}

.button {
  display: inline-flex;
  min-height: 3rem;
  align-items: center;
  justify-content: center;
  padding: 0.6875rem 1.25rem;
  border: 1px solid transparent;
  border-radius: var(--radius-small);
  font-weight: 700;
  line-height: 1.4;
  text-decoration: none;
  transition:
    color var(--transition-fast),
    background-color var(--transition-fast),
    border-color var(--transition-fast);
}

.button--primary {
  color: var(--color-white);
  background: var(--color-primary);
  border-color: var(--color-primary);
}

.button--primary:hover,
.button--primary:focus-visible {
  color: var(--color-white);
  background: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
}

.button--secondary {
  color: var(--color-primary-dark);
  background: transparent;
  border-color: var(--color-primary);
}

.button--secondary:hover,
.button--secondary:focus-visible {
  color: var(--color-primary-dark);
  background: var(--color-primary-light);
  border-color: var(--color-primary-dark);
}

.hero__media {
  min-width: 0;
  aspect-ratio: 5 / 4;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-small);
  background: var(--color-primary-light);
}

.hero__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 65% 55%;
}

@media (max-width: 56.25rem) {
  .hero {
    padding-block: clamp(3rem, 8vw, 4.5rem);
  }

  .hero__inner {
    grid-template-columns: minmax(0, 1fr);
    gap: clamp(2rem, 6vw, 3rem);
  }

  .hero__content {
    max-width: 44rem;
  }

  .hero__media {
    width: 100%;
    aspect-ratio: 4 / 3;
  }

  .hero__media img {
    object-position: 65% 58%;
  }
}

/* 关于有元 */
.about {
  padding-block: clamp(3.75rem, 6vw, 5.5rem);
  background: var(--color-bg-secondary);
}

.about__title {
  display: flex;
  margin: 0 0 clamp(2rem, 3.5vw, 3rem);
  align-items: center;
  gap: 0.75rem;
  color: var(--color-text);
  font-size: clamp(1.5rem, 2.4vw, 2rem);
  letter-spacing: -0.015em;
}

.about__title::before {
  width: 1.75rem;
  height: 2px;
  flex: 0 0 auto;
  background: var(--color-accent);
  content: "";
}

.about__introduction {
  max-width: 46rem;
}

.about__introduction p {
  margin: 0;
  color: var(--color-text-secondary);
  font-size: clamp(1rem, 1.3vw, 1.125rem);
  line-height: 1.9;
}

.about__introduction p + p {
  margin-top: 1.25rem;
}

.about__metrics {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: clamp(2.5rem, 5vw, 3.5rem) 0 0;
  border-block: 1px solid var(--color-border);
}

.about__metric {
  min-width: 0;
  padding: clamp(1.5rem, 4vw, 2.25rem) clamp(1rem, 3vw, 2rem);
}

.about__metric:nth-child(even) {
  border-left: 1px solid var(--color-border);
}

.about__metric:nth-child(n + 3) {
  border-top: 1px solid var(--color-border);
}

.about__metric dt {
  color: var(--color-primary);
  font-size: clamp(1.5rem, 3vw, 2.5rem);
  font-weight: 650;
  letter-spacing: -0.035em;
  line-height: 1.15;
  white-space: nowrap;
}

.about__metric dd {
  margin: 0.75rem 0 0;
  color: var(--color-text-secondary);
  font-size: clamp(0.9375rem, 1.5vw, 1rem);
  line-height: 1.65;
}

@media (min-width: 64rem) {
  .about__metrics {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .about__metric:nth-child(n) {
    border-top: 0;
    border-left: 1px solid var(--color-border);
  }

  .about__metric:first-child {
    border-left: 0;
  }
}

/* 专业服务 */
.services {
  padding-block: clamp(4rem, 7vw, 6rem);
  background: var(--color-bg);
}

.services__header {
  display: grid;
  grid-template-columns: minmax(0, 16rem) minmax(0, 1fr);
  align-items: end;
  gap: clamp(1.5rem, 4vw, 4rem);
  margin-bottom: clamp(2rem, 4vw, 3rem);
}

.services__title {
  display: flex;
  margin: 0;
  align-items: center;
  gap: 0.75rem;
  font-size: clamp(1.5rem, 2.4vw, 2rem);
  letter-spacing: -0.015em;
}

.services__title::before {
  width: 1.75rem;
  height: 2px;
  flex: 0 0 auto;
  background: var(--color-accent);
  content: "";
}

.services__introduction {
  max-width: 42rem;
  margin: 0;
  color: var(--color-text-secondary);
  font-size: clamp(1rem, 1.3vw, 1.0625rem);
  line-height: 1.8;
}

.services__list {
  border-block: 1px solid var(--color-border);
}

.service-item {
  display: grid;
  grid-template-columns: 5rem minmax(13rem, 16rem) minmax(0, 1fr);
  align-items: start;
  gap: clamp(1.5rem, 3vw, 3rem);
  padding-block: clamp(1.75rem, 3vw, 2.5rem);
}

.service-item + .service-item {
  border-top: 1px solid var(--color-border);
}

.service-item__number {
  color: var(--color-primary);
  font-size: clamp(1.375rem, 2.25vw, 1.75rem);
  font-weight: 650;
  letter-spacing: 0.02em;
  line-height: 1.3;
}

.service-item h3 {
  margin: 0;
  color: var(--color-text);
  font-size: clamp(1.125rem, 1.6vw, 1.25rem);
  letter-spacing: -0.01em;
  line-height: 1.5;
}

.service-item__details {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.625rem clamp(1.5rem, 3vw, 3rem);
  min-width: 0;
  margin: 0;
  padding: 0;
  color: var(--color-text-secondary);
  list-style: none;
}

.service-item__details li {
  position: relative;
  min-width: 0;
  padding-left: 1rem;
  line-height: 1.65;
  overflow-wrap: anywhere;
}

.service-item__details li::before {
  position: absolute;
  top: 0.74em;
  left: 0;
  width: 0.3rem;
  height: 0.3rem;
  background: var(--color-primary);
  border-radius: 50%;
  content: "";
}

@media (max-width: 56.25rem) {
  .services__header {
    grid-template-columns: minmax(0, 1fr);
    gap: 1rem;
  }

  .service-item {
    grid-template-columns: 4rem minmax(0, 1fr);
    gap: 0.875rem 1.5rem;
  }

  .service-item__details {
    grid-column: 2;
  }
}

@media (max-width: 40rem) {
  .services {
    padding-block: 3.75rem;
  }

  .service-item {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.625rem;
    padding-block: 1.75rem;
  }

  .service-item__details {
    grid-template-columns: minmax(0, 1fr);
    grid-column: 1;
    gap: 0.5rem;
    margin-top: 0.375rem;
  }
}

/* 项目经验 */
.projects {
  padding-block: clamp(4rem, 7vw, 6rem);
  background: var(--color-bg-secondary);
}

.projects__title {
  display: flex;
  margin: 0 0 clamp(2rem, 4vw, 3rem);
  align-items: center;
  gap: 0.75rem;
  font-size: clamp(1.5rem, 2.4vw, 2rem);
  letter-spacing: -0.015em;
}

.projects__title::before {
  width: 1.75rem;
  height: 2px;
  flex: 0 0 auto;
  background: var(--color-accent);
  content: "";
}

.projects__layout {
  max-width: 52rem;
}

.projects__description {
  margin: 0;
  color: var(--color-text-secondary);
  font-size: clamp(1rem, 1.3vw, 1.125rem);
  line-height: 1.9;
}

.projects__organizations {
  margin-top: clamp(2rem, 4vw, 2.75rem);
  padding-top: clamp(1.75rem, 3vw, 2.25rem);
  border-top: 1px solid var(--color-border);
}

.projects__organizations h3 {
  margin: 0 0 1.25rem;
  color: var(--color-text);
  font-size: 1.125rem;
  letter-spacing: 0.01em;
}

.projects__organization-text {
  margin: 0;
  color: var(--color-text-secondary);
  font-size: 1rem;
  line-height: 1.85;
  overflow-wrap: anywhere;
}

@media (max-width: 40rem) {
  .projects {
    padding-block: 3.75rem;
  }
}

/* 联系我们 */
.contact {
  padding-block: clamp(4rem, 7vw, 6rem);
  background: var(--color-bg);
}

.contact__title {
  display: flex;
  margin: 0 0 clamp(2rem, 4vw, 3rem);
  align-items: center;
  gap: 0.75rem;
  font-size: clamp(1.5rem, 2.4vw, 2rem);
  letter-spacing: -0.015em;
}

.contact__title::before {
  width: 1.75rem;
  height: 2px;
  flex: 0 0 auto;
  background: var(--color-accent);
  content: "";
}

.contact__details {
  max-width: 52rem;
  font-style: normal;
}

.contact__list {
  margin: 0;
  border-block: 1px solid var(--color-border);
}

.contact__item {
  display: grid;
  grid-template-columns: minmax(6rem, 9rem) minmax(0, 1fr);
  gap: clamp(1rem, 3vw, 2.5rem);
  padding-block: clamp(1.25rem, 2.5vw, 1.75rem);
}

.contact__item + .contact__item {
  border-top: 1px solid var(--color-border);
}

.contact__item dt {
  color: var(--color-text);
  font-weight: 700;
}

.contact__item dd {
  min-width: 0;
  margin: 0;
  color: var(--color-text-secondary);
  overflow-wrap: anywhere;
}

.contact__link {
  display: inline-flex;
  min-height: 2.75rem;
  align-items: center;
  color: var(--color-primary-dark);
  font-weight: 650;
}

.contact__link:hover,
.contact__link:focus-visible {
  color: var(--color-primary);
}

@media (max-width: 40rem) {
  .contact {
    padding-block: 3.75rem;
  }

  .contact__item {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.25rem;
  }
}

/* 页脚 */
.site-footer {
  padding-block: 1.5rem;
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
}

.site-footer p {
  margin: 0;
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  line-height: 1.7;
  text-align: center;
}

.site-footer__rights {
  white-space: nowrap;
}

/* Header 与主导航 */
.site-header {
  position: sticky;
  z-index: 100;
  top: 0;
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
}

.site-header__inner {
  display: flex;
  min-height: var(--header-height);
  align-items: center;
  justify-content: space-between;
  gap: clamp(1.5rem, 3vw, 3rem);
}

.site-brand {
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 0.75rem;
  color: var(--color-text);
  text-decoration: none;
}

.site-brand:hover {
  color: var(--color-primary-dark);
}

.site-brand__logo {
  width: 3rem;
  height: auto;
  flex: 0 0 auto;
}

.site-brand__name {
  font-size: 1.0625rem;
  font-weight: 700;
  line-height: 1.35;
  white-space: nowrap;
}

.site-nav {
  margin-left: auto;
}

.site-nav__list {
  display: flex;
  margin: 0;
  align-items: center;
  gap: clamp(0.5rem, 1.25vw, 1.25rem);
  padding: 0;
  list-style: none;
}

.site-nav a {
  display: block;
  padding: 0.625rem 0.25rem;
  color: var(--color-text);
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.4;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--transition-fast);
}

.site-nav a:hover,
.site-nav a:focus-visible {
  color: var(--color-primary);
}

.site-nav .site-nav__cta {
  padding-inline: 0.875rem;
  color: var(--color-white);
  background: var(--color-primary);
  border-radius: var(--radius-small);
  transition:
    color var(--transition-fast),
    background-color var(--transition-fast);
}

.site-nav .site-nav__cta:hover,
.site-nav .site-nav__cta:focus-visible {
  color: var(--color-white);
  background: var(--color-primary-dark);
}

.nav-toggle {
  display: none;
  width: 2.75rem;
  height: 2.75rem;
  flex: 0 0 auto;
  align-items: center;
  justify-content: center;
  padding: 0;
  color: var(--color-text);
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-small);
  cursor: pointer;
}

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

.nav-toggle__icon,
.nav-toggle__icon::before,
.nav-toggle__icon::after {
  display: block;
  width: 1.25rem;
  height: 2px;
  background: currentColor;
  transition:
    transform var(--transition-fast),
    opacity var(--transition-fast);
}

.nav-toggle__icon {
  position: relative;
}

.nav-toggle__icon::before,
.nav-toggle__icon::after {
  position: absolute;
  left: 0;
  content: "";
}

.nav-toggle__icon::before {
  transform: translateY(-0.4rem);
}

.nav-toggle__icon::after {
  transform: translateY(0.4rem);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__icon {
  background: transparent;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__icon::before {
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__icon::after {
  transform: rotate(-45deg);
}

@media (max-width: 52rem) {
  :root {
    --header-height: 4.5rem;
  }

  .site-header__inner {
    flex-wrap: wrap;
    gap: 0;
  }

  .site-brand {
    gap: 0.625rem;
    min-height: var(--header-height);
  }

  .site-brand__logo {
    width: 2.625rem;
  }

  .site-brand__name {
    font-size: 1rem;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .site-nav {
    display: none;
    width: 100%;
    margin-left: 0;
    border-top: 1px solid var(--color-border);
  }

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

  .site-nav__list {
    display: block;
    padding-block: 0.5rem 1rem;
  }

  .site-nav a {
    padding: 0.75rem 0.25rem;
    font-size: 1rem;
  }

  .site-nav .site-nav__cta {
    margin-top: 0.375rem;
    padding-inline: 0.875rem;
    text-align: center;
  }
}

@media (max-width: 24rem) {
  .site-brand__logo {
    width: 2.375rem;
  }

  .site-brand__name {
    font-size: 0.9375rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
  }
}