/* 职在北方 — 科技 · 新能源 · 自然 · 教育 */
:root {
  --ink: #14201a;
  --ink-soft: #3a4f44;
  --mist: #f2f7f4;
  --leaf: #e6f2eb;
  --green-deep: #0b3d2e;
  --green-mid: #1a6b4a;
  --green-bright: #2d9b6a;
  --teal: #0e7c7b;
  --sun: #c4a35a;
  --white: #ffffff;
  --line: rgba(20, 32, 26, 0.12);
  --shadow: 0 18px 40px rgba(11, 61, 46, 0.12);
  --radius: 4px;
  --font-display: "Noto Serif SC", "Songti SC", serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", sans-serif;
  --max: 1120px;
  --nav-h: 72px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--mist);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

.container {
  width: min(100% - 2rem, var(--max));
  margin-inline: auto;
}

/* —— Nav —— */
.site-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  transition: background 0.35s ease, box-shadow 0.35s ease, backdrop-filter 0.35s ease;
}

.site-header.is-scrolled {
  background: rgba(242, 247, 244, 0.92);
  backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 var(--line);
}

.site-header.is-scrolled .brand,
.site-header.is-scrolled .nav-link,
.site-header.is-scrolled .menu-toggle {
  color: var(--ink);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: min(100% - 2rem, var(--max));
  margin-inline: auto;
}

.brand {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--white);
  transition: color 0.3s ease;
}

.nav-links {
  display: none;
  gap: 2rem;
  align-items: center;
}

.nav-link {
  font-size: 0.9rem;
  color: rgba(255, 255, 255, 0.88);
  letter-spacing: 0.04em;
  transition: color 0.25s ease, opacity 0.25s ease;
}

.nav-link:hover {
  color: var(--white);
  opacity: 1;
}

.menu-toggle {
  display: flex;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--white);
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: currentColor;
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.menu-toggle.is-open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.menu-toggle.is-open span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.is-open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.mobile-nav {
  position: fixed;
  inset: var(--nav-h) 0 0;
  background: rgba(11, 61, 46, 0.97);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  transform: translateX(100%);
  transition: transform 0.35s ease;
  z-index: 99;
}

.mobile-nav.is-open {
  transform: translateX(0);
}

.mobile-nav a {
  color: var(--white);
  font-size: 1.15rem;
  font-family: var(--font-display);
  letter-spacing: 0.08em;
}

/* —— Hero —— */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: flex-end;
  overflow: hidden;
  background: var(--green-deep);
}

.hero-bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  animation: heroZoom 18s ease-out forwards;
}

@keyframes heroZoom {
  from {
    transform: scale(1.08);
  }
  to {
    transform: scale(1);
  }
}

.hero-veil {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(
      180deg,
      rgba(11, 61, 46, 0.45) 0%,
      rgba(11, 61, 46, 0.55) 40%,
      rgba(11, 61, 46, 0.88) 100%
    ),
    radial-gradient(ellipse at 70% 20%, rgba(45, 155, 106, 0.25), transparent 55%);
}

.hero-content {
  position: relative;
  z-index: 2;
  width: min(100% - 2rem, var(--max));
  margin: 0 auto;
  padding: calc(var(--nav-h) + 3rem) 0 4.5rem;
  color: var(--white);
  animation: fadeUp 0.9s ease 0.15s both;
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(28px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero-brand {
  font-family: var(--font-display);
  font-size: clamp(2.6rem, 8vw, 4.5rem);
  font-weight: 700;
  letter-spacing: 0.12em;
  line-height: 1.15;
  margin-bottom: 1.25rem;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 3.2vw, 1.75rem);
  font-weight: 500;
  letter-spacing: 0.04em;
  line-height: 1.45;
  max-width: 18em;
  margin-bottom: 1rem;
  color: rgba(255, 255, 255, 0.95);
}

.hero-desc {
  font-size: 1rem;
  color: rgba(255, 255, 255, 0.78);
  max-width: 32em;
  margin-bottom: 2rem;
}

.cta-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.85rem 1.6rem;
  font-size: 0.95rem;
  font-family: var(--font-body);
  letter-spacing: 0.06em;
  border: none;
  cursor: pointer;
  transition: background 0.25s ease, color 0.25s ease, border-color 0.25s ease, transform 0.25s ease;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-primary {
  background: var(--green-bright);
  color: var(--white);
}

.btn-primary:hover {
  background: #35ad78;
}

.btn-ghost {
  background: transparent;
  color: var(--white);
  border: 1px solid rgba(255, 255, 255, 0.45);
}

.btn-ghost:hover {
  border-color: var(--white);
  background: rgba(255, 255, 255, 0.08);
}

.scroll-hint {
  position: absolute;
  bottom: 1.5rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  width: 1px;
  height: 40px;
  background: linear-gradient(to bottom, transparent, rgba(255, 255, 255, 0.7));
  animation: pulseLine 2s ease-in-out infinite;
}

@keyframes pulseLine {
  0%,
  100% {
    opacity: 0.35;
    transform: translateX(-50%) scaleY(0.85);
  }
  50% {
    opacity: 1;
    transform: translateX(-50%) scaleY(1);
  }
}

/* —— Sections —— */
.section {
  padding: 5rem 0;
}

.section-label {
  font-size: 0.8rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: 0.75rem;
  font-weight: 500;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(1.75rem, 4vw, 2.35rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  line-height: 1.3;
  margin-bottom: 1rem;
  color: var(--green-deep);
}

.section-lead {
  color: var(--ink-soft);
  max-width: 36em;
  font-size: 1.05rem;
}

/* —— About —— */
.about {
  background: var(--white);
}

.about-grid {
  display: grid;
  gap: 2.5rem;
  align-items: center;
}

.about-visual {
  position: relative;
  overflow: hidden;
  min-height: 260px;
}

.about-visual img {
  width: 100%;
  height: 100%;
  min-height: 280px;
  object-fit: cover;
  animation: fadeIn 1s ease both;
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

.about-visual::after {
  content: "";
  position: absolute;
  inset: auto 0 0 auto;
  width: 40%;
  height: 6px;
  background: var(--green-bright);
}

.about-copy p {
  color: var(--ink-soft);
  margin-bottom: 1.1rem;
}

.about-copy p:last-child {
  margin-bottom: 0;
}

.about-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1.75rem;
}

.about-tags span {
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  color: var(--green-mid);
  padding: 0.35rem 0;
  border-bottom: 1px solid var(--green-bright);
}

/* —— Services —— */
.services {
  background:
    linear-gradient(165deg, var(--leaf) 0%, var(--mist) 55%, #e8f4ef 100%);
  position: relative;
}

.services::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle at 1px 1px, rgba(26, 107, 74, 0.07) 1px, transparent 0);
  background-size: 28px 28px;
  pointer-events: none;
}

.services .container {
  position: relative;
}

.services-head {
  margin-bottom: 3rem;
}

.service-list {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line);
}

.service-item {
  display: grid;
  gap: 0.75rem;
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--line);
  transition: padding-left 0.35s ease, background 0.35s ease;
}

.service-item:hover {
  padding-left: 0.5rem;
}

.service-num {
  font-family: var(--font-display);
  font-size: 0.85rem;
  color: var(--teal);
  letter-spacing: 0.12em;
}

.service-name {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--green-deep);
}

.service-desc {
  color: var(--ink-soft);
  max-width: 42em;
  font-size: 0.98rem;
}

/* —— Why —— */
.why {
  background: var(--green-deep);
  color: var(--white);
  position: relative;
  overflow: hidden;
}

.why::before {
  content: "";
  position: absolute;
  top: -20%;
  right: -10%;
  width: 55%;
  height: 80%;
  background: radial-gradient(ellipse, rgba(45, 155, 106, 0.28), transparent 70%);
  pointer-events: none;
}

.why .section-label {
  color: rgba(196, 163, 90, 0.9);
}

.why .section-title {
  color: var(--white);
}

.why .section-lead {
  color: rgba(255, 255, 255, 0.72);
}

.why-head {
  margin-bottom: 3rem;
}

.why-grid {
  display: grid;
  gap: 2.5rem;
}

.why-item {
  border-top: 1px solid rgba(255, 255, 255, 0.18);
  padding-top: 1.5rem;
  animation: fadeUp 0.7s ease both;
}

.why-item:nth-child(2) {
  animation-delay: 0.12s;
}

.why-item:nth-child(3) {
  animation-delay: 0.24s;
}

.why-index {
  font-family: var(--font-display);
  font-size: 2rem;
  color: var(--sun);
  letter-spacing: 0.08em;
  margin-bottom: 0.75rem;
  line-height: 1;
}

.why-title {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  margin-bottom: 0.65rem;
}

.why-text {
  color: rgba(255, 255, 255, 0.72);
  font-size: 0.98rem;
  max-width: 28em;
}

/* —— CTA band —— */
.cta-band {
  background: var(--white);
  padding: 4rem 0;
  text-align: center;
}

.cta-band h2 {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 3.5vw, 2rem);
  letter-spacing: 0.06em;
  color: var(--green-deep);
  margin-bottom: 0.75rem;
}

.cta-band p {
  color: var(--ink-soft);
  margin-bottom: 1.75rem;
}

/* —— Footer —— */
.site-footer {
  background: #0a2e23;
  color: rgba(255, 255, 255, 0.75);
  padding: 3rem 0 2rem;
}

.footer-top {
  display: grid;
  gap: 2rem;
  margin-bottom: 2.5rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.12);
}

.footer-brand {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--white);
  margin-bottom: 0.5rem;
}

.footer-tagline {
  font-size: 0.9rem;
  max-width: 22em;
  line-height: 1.6;
}

.footer-contact h4 {
  font-size: 0.8rem;
  letter-spacing: 0.14em;
  color: rgba(255, 255, 255, 0.45);
  margin-bottom: 0.75rem;
  font-weight: 500;
}

.footer-contact p {
  font-size: 0.95rem;
  margin-bottom: 0.35rem;
}

.footer-bottom {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
  text-align: center;
}

.footer-copy {
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.45);
  order: 2;
}

.footer-icp {
  order: 1;
  font-size: 0.9rem;
  letter-spacing: 0.04em;
}

.footer-icp a {
  color: rgba(255, 255, 255, 0.85);
  border-bottom: 1px solid rgba(255, 255, 255, 0.35);
  padding-bottom: 1px;
  transition: color 0.25s ease, border-color 0.25s ease;
}

.footer-icp a:hover {
  color: var(--white);
  border-color: var(--white);
}

/* —— Reveal on scroll —— */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

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

/* —— Desktop —— */
@media (min-width: 768px) {
  .menu-toggle {
    display: none;
  }

  .nav-links {
    display: flex;
  }

  .mobile-nav {
    display: none;
  }

  .about-grid {
    grid-template-columns: 1fr 1.05fr;
    gap: 3.5rem;
  }

  .service-item {
    grid-template-columns: 4rem 12rem 1fr;
    gap: 1.5rem;
    align-items: baseline;
    padding: 2rem 0;
  }

  .service-item:hover {
    padding-left: 0.75rem;
  }

  .why-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
  }

  .footer-top {
    grid-template-columns: 1.4fr 1fr;
    align-items: start;
  }

  .footer-bottom {
    position: relative;
  }

  .footer-icp {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
  }

  .footer-copy {
    width: 100%;
    text-align: left;
    order: 0;
  }
}

@media (min-width: 1024px) {
  .section {
    padding: 6.5rem 0;
  }

  .hero-content {
    padding-bottom: 5.5rem;
  }
}