:root {
  --brand: #1f4d3a;
  --brand-mid: #2f6b4f;
  --brand-soft: #dce8e1;
  --ink: #14201a;
  --muted: #5a6b62;
  --paper: #f3f6f4;
  --white: #ffffff;
  --line: rgba(31, 77, 58, 0.12);
  --font-display: "Noto Serif SC", "Songti SC", serif;
  --font-body: "Noto Sans SC", "PingFang SC", sans-serif;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --nav-h: 4.25rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.7;
  background:
    radial-gradient(1200px 600px at 10% -10%, rgba(47, 107, 79, 0.12), transparent 55%),
    radial-gradient(900px 500px at 100% 20%, rgba(31, 77, 58, 0.08), transparent 50%),
    var(--paper);
  -webkit-font-smoothing: antialiased;
}

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

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

h1,
h2,
h3 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.25;
  margin: 0;
}

p {
  margin: 0;
}

/* —— Nav —— */
.site-nav {
  position: fixed;
  inset: 0 0 auto;
  z-index: 40;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(1.25rem, 4vw, 3.5rem);
  transition: background 0.35s var(--ease), backdrop-filter 0.35s var(--ease), box-shadow 0.35s var(--ease);
}

.site-nav.is-scrolled {
  background: rgba(243, 246, 244, 0.88);
  backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 var(--line);
}

.site-nav__brand {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--white);
  letter-spacing: 0.04em;
  transition: color 0.3s var(--ease);
}

.site-nav.is-scrolled .site-nav__brand {
  color: var(--brand);
}

.site-nav__links {
  display: none;
  align-items: center;
  gap: 1.75rem;
}

.site-nav__links a {
  font-size: 0.9375rem;
  color: rgba(255, 255, 255, 0.88);
  transition: color 0.25s var(--ease);
}

.site-nav.is-scrolled .site-nav__links a {
  color: var(--muted);
}

.site-nav__links a:hover {
  color: var(--white);
}

.site-nav.is-scrolled .site-nav__links a:hover {
  color: var(--brand);
}

.site-nav__cta {
  padding: 0.55rem 1.1rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.16);
  border: 1px solid rgba(255, 255, 255, 0.35);
}

.site-nav.is-scrolled .site-nav__cta {
  background: var(--brand);
  border-color: var(--brand);
  color: var(--white) !important;
}

.site-nav__menu {
  width: 2.5rem;
  height: 2.5rem;
  border: 0;
  background: transparent;
  display: grid;
  place-content: center;
  gap: 6px;
  cursor: pointer;
}

.site-nav__menu span {
  display: block;
  width: 1.35rem;
  height: 2px;
  background: var(--white);
  transition: background 0.25s var(--ease);
}

.site-nav.is-scrolled .site-nav__menu span {
  background: var(--brand);
}

.nav-drawer {
  position: fixed;
  inset: var(--nav-h) 1rem auto;
  z-index: 39;
  display: grid;
  gap: 0.25rem;
  padding: 1rem;
  background: var(--white);
  border-radius: 1rem;
  box-shadow: 0 18px 40px rgba(20, 32, 26, 0.14);
}

.nav-drawer[hidden] {
  display: none;
}

.nav-drawer a {
  padding: 0.85rem 0.75rem;
  border-radius: 0.65rem;
  color: var(--ink);
  font-weight: 500;
}

.nav-drawer a:hover {
  background: var(--brand-soft);
}

@media (min-width: 860px) {
  .site-nav__links {
    display: flex;
  }

  .site-nav__menu {
    display: none;
  }
}

/* —— Buttons —— */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 3rem;
  padding: 0 1.4rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.975rem;
  transition: transform 0.25s var(--ease), background 0.25s var(--ease), color 0.25s var(--ease);
}

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

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

.btn--primary:hover {
  background: var(--brand-mid);
}

.btn--ghost {
  color: var(--white);
  border: 1px solid rgba(255, 255, 255, 0.55);
  background: rgba(255, 255, 255, 0.08);
}

.btn--ghost:hover {
  background: rgba(255, 255, 255, 0.18);
}

.btn--soft {
  color: var(--brand);
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.65);
  cursor: pointer;
}

.btn--soft:hover {
  background: var(--white);
}

/* —— Phone preview —— */
.preview {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: clamp(2rem, 5vw, 4rem);
  align-items: center;
  padding: clamp(3.5rem, 8vh, 5.5rem) clamp(1.25rem, 4vw, 3.5rem);
  background:
    radial-gradient(700px 420px at 85% 30%, rgba(47, 107, 79, 0.16), transparent 60%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.55), transparent 40%),
    var(--paper);
}

.preview__eyebrow {
  font-size: 0.875rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--brand-mid);
  margin-bottom: 0.75rem;
  font-weight: 600;
}

.preview__copy h2 {
  font-size: clamp(1.75rem, 3.5vw, 2.35rem);
  color: var(--brand);
  margin-bottom: 1rem;
}

.preview__copy > p:not(.preview__eyebrow) {
  color: var(--muted);
  max-width: 28em;
  margin-bottom: 1.75rem;
}

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

.preview__stage {
  display: flex;
  justify-content: center;
  perspective: 1200px;
}

.phone {
  position: relative;
  width: min(320px, 78vw);
  aspect-ratio: 9 / 19.2;
  padding: 12px;
  border-radius: 2.15rem;
  background: linear-gradient(160deg, #1a2e26 0%, #0d1814 55%, #243d32 100%);
  box-shadow:
    0 28px 60px rgba(20, 32, 26, 0.28),
    inset 0 0 0 1px rgba(255, 255, 255, 0.08);
  animation: phone-float 7s var(--ease) infinite alternate;
}

.phone__notch {
  position: absolute;
  top: 18px;
  left: 50%;
  z-index: 2;
  width: 34%;
  height: 18px;
  transform: translateX(-50%);
  border-radius: 999px;
  background: #0a1210;
}

.phone__screen {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
  border-radius: 1.65rem;
  background: #eef2ef;
}

.phone__screen iframe {
  display: block;
  width: 100%;
  height: 100%;
  border: 0;
  background: #eef2ef;
}

.phone__placeholder {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 1.5rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.9rem;
  background: linear-gradient(180deg, #f7faf8, #e8eee9);
  transition: opacity 0.4s var(--ease);
}

.phone__placeholder.is-hidden {
  opacity: 0;
  pointer-events: none;
}

.phone__home {
  position: absolute;
  left: 50%;
  bottom: 8px;
  width: 28%;
  height: 4px;
  transform: translateX(-50%);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.28);
}

@keyframes phone-float {
  from {
    transform: translateY(0) rotateY(-4deg);
  }
  to {
    transform: translateY(-10px) rotateY(4deg);
  }
}

@media (max-width: 900px) {
  .preview {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .preview__copy > p:not(.preview__eyebrow) {
    margin-left: auto;
    margin-right: auto;
  }

  .preview__actions {
    justify-content: center;
  }
}

@media (max-width: 640px) {
  .preview__stage {
    display: none;
  }

  .preview__copy::after {
    content: "当前已是手机浏览，可直接打开手机端体验。";
    display: block;
    margin-top: 0.5rem;
    color: var(--muted);
    font-size: 0.95rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .phone {
    animation: none;
  }
}

/* —— Hero —— */
.hero {
  position: relative;
  min-height: 100svh;
  display: grid;
  align-items: end;
  color: var(--white);
  overflow: hidden;
}

.hero__media {
  position: absolute;
  inset: 0;
}

.hero__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  transform: scale(1.04);
  animation: hero-zoom 18s var(--ease) forwards;
}

.hero__veil {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(180deg, rgba(12, 28, 22, 0.35) 0%, rgba(12, 28, 22, 0.18) 38%, rgba(12, 28, 22, 0.78) 100%),
    linear-gradient(90deg, rgba(12, 28, 22, 0.45) 0%, transparent 55%);
}

.hero__content {
  position: relative;
  z-index: 1;
  width: min(720px, 100%);
  padding: calc(var(--nav-h) + 2rem) clamp(1.25rem, 4vw, 3.5rem) clamp(3.5rem, 8vh, 5.5rem);
}

.hero__brand {
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 7vw, 4.25rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  line-height: 1.1;
  margin-bottom: 1.1rem;
}

.hero__title {
  font-size: clamp(1.35rem, 3.2vw, 1.85rem);
  font-weight: 600;
  max-width: 18em;
  margin-bottom: 0.85rem;
}

.hero__lead {
  font-size: clamp(1rem, 2vw, 1.125rem);
  color: rgba(255, 255, 255, 0.88);
  max-width: 30em;
  margin-bottom: 1.75rem;
}

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

@keyframes hero-zoom {
  from {
    transform: scale(1.06);
  }
  to {
    transform: scale(1);
  }
}

/* —— Band / Split —— */
.band,
.split,
.features,
.modules,
.scenes,
.cta {
  padding: clamp(4rem, 10vw, 7rem) clamp(1.25rem, 4vw, 3.5rem);
}

.band {
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
  align-items: center;
}

.band__copy h2,
.split__copy h2,
.features__head h2,
.modules__head h2,
.cta__inner h2 {
  font-size: clamp(1.75rem, 3.5vw, 2.45rem);
  color: var(--brand);
  margin-bottom: 1rem;
}

.band__copy p,
.split__copy p,
.features__head p,
.modules__head p,
.cta__inner p {
  color: var(--muted);
  max-width: 36em;
}

.band__figure,
.split__figure,
.modules__visual {
  margin: 0;
  overflow: hidden;
  border-radius: 1.25rem;
}

.band__figure img,
.split__figure img,
.modules__visual img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.split {
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
  align-items: center;
  background: linear-gradient(180deg, transparent, rgba(31, 77, 58, 0.05), transparent);
}

.steps {
  list-style: none;
  margin: 1.75rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.9rem;
}

.steps li {
  display: flex;
  align-items: baseline;
  gap: 0.85rem;
  font-weight: 500;
  color: var(--ink);
}

.steps span {
  font-family: var(--font-display);
  color: var(--brand-mid);
  font-size: 0.95rem;
  min-width: 1.75rem;
}

@media (min-width: 900px) {
  .band {
    grid-template-columns: 0.95fr 1.05fr;
  }

  .split {
    grid-template-columns: 1.05fr 0.95fr;
  }
}

/* —— Modules —— */
.modules {
  background:
    linear-gradient(160deg, rgba(31, 77, 58, 0.06), transparent 40%),
    var(--paper);
}

.modules__head {
  max-width: 36em;
  margin-bottom: clamp(2rem, 4vw, 2.75rem);
}

.modules__list {
  list-style: none;
  margin: 0 0 clamp(2rem, 5vw, 3rem);
  padding: 0;
  display: grid;
  gap: 1.5rem 2rem;
}

.modules__list h3 {
  font-size: 1.2rem;
  color: var(--brand);
  margin-bottom: 0.45rem;
}

.modules__list p {
  color: var(--muted);
  font-size: 0.98rem;
}

.modules__list li {
  padding-top: 1rem;
  border-top: 1px solid var(--line);
}

@media (min-width: 800px) {
  .modules__list {
    grid-template-columns: 1fr 1fr;
  }
}

/* —— Features —— */
.features {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(900px 520px at 0% 0%, rgba(47, 107, 79, 0.14), transparent 55%),
    radial-gradient(700px 480px at 100% 40%, rgba(31, 77, 58, 0.1), transparent 50%),
    linear-gradient(180deg, #e8efe9 0%, var(--paper) 42%, #e6ece8 100%);
}

.features__head {
  position: relative;
  z-index: 1;
  max-width: 28em;
  margin-bottom: clamp(2.5rem, 6vw, 4rem);
}

.features__eyebrow {
  font-size: 0.8rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--brand-mid);
  font-weight: 600;
  margin-bottom: 0.85rem;
}

.features__head h2 {
  font-family: var(--font-display);
  font-size: clamp(2.1rem, 5vw, 3.1rem);
  letter-spacing: 0.04em;
  line-height: 1.15;
}

.features__rail {
  display: none;
}

.features__stack {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(1.25rem, 2.5vw, 1.75rem);
}

.feature {
  display: grid;
  gap: 1.25rem 2rem;
  padding: clamp(1.75rem, 4vw, 2.75rem);
  border-radius: 0;
  border-left: 4px solid var(--brand);
  background:
    linear-gradient(105deg, rgba(255, 255, 255, 0.92) 0%, rgba(255, 255, 255, 0.72) 100%);
  box-shadow: none;
}

.feature__index {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(3.25rem, 8vw, 5.5rem);
  font-weight: 700;
  line-height: 0.85;
  letter-spacing: -0.04em;
  color: rgba(31, 77, 58, 0.16);
  user-select: none;
}

.feature h3 {
  font-family: var(--font-display);
  font-size: clamp(1.55rem, 3vw, 2rem);
  color: var(--brand);
  letter-spacing: 0.03em;
  margin-bottom: 0.65rem;
}

.feature__lead {
  color: var(--muted);
  max-width: 36em;
  margin-bottom: 1.35rem;
  font-size: 1.05rem;
}

.feature__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.85rem 1.5rem;
}

.feature__list li {
  position: relative;
  padding: 0.15rem 0 0.15rem 1.15rem;
  color: var(--ink);
  font-size: 0.98rem;
  line-height: 1.55;
  border-bottom: 1px solid rgba(31, 77, 58, 0.08);
  padding-bottom: 0.75rem;
}

.feature__list li:last-child {
  border-bottom: 0;
  padding-bottom: 0.15rem;
}

.feature__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.7em;
  width: 0.55rem;
  height: 2px;
  background: var(--brand-mid);
}

.feature--dark {
  border-left-color: rgba(255, 255, 255, 0.45);
  background:
    linear-gradient(125deg, rgba(20, 42, 32, 0.97) 0%, rgba(31, 77, 58, 0.94) 55%, rgba(47, 107, 79, 0.9) 100%),
    url("../assets/scene-ops.jpg") right center / cover;
  color: var(--white);
}

.feature--dark .feature__index {
  color: rgba(255, 255, 255, 0.14);
}

.feature--dark h3 {
  color: var(--white);
}

.feature--dark .feature__lead {
  color: rgba(255, 255, 255, 0.78);
}

.feature--dark .feature__list li {
  color: rgba(255, 255, 255, 0.92);
  border-bottom-color: rgba(255, 255, 255, 0.12);
}

.feature--dark .feature__list li::before {
  background: rgba(255, 255, 255, 0.75);
}

@media (min-width: 900px) {
  .features {
    padding-right: clamp(1.25rem, 4vw, 3.5rem);
  }

  .features__rail {
    display: flex;
    position: absolute;
    top: clamp(8rem, 18vh, 12rem);
    right: 1.25rem;
    z-index: 0;
    writing-mode: vertical-rl;
    flex-direction: row;
    gap: 1.75rem;
    font-family: var(--font-display);
    font-size: 0.85rem;
    letter-spacing: 0.28em;
    color: rgba(31, 77, 58, 0.28);
    pointer-events: none;
  }

  .feature {
    grid-template-columns: minmax(5.5rem, 7.5rem) minmax(0, 1fr);
    align-items: start;
    padding: clamp(2.25rem, 4vw, 3.25rem) clamp(2rem, 4vw, 3.5rem);
  }

  .feature__index {
    padding-top: 0.15rem;
  }

  .feature__list {
    grid-template-columns: 1fr 1fr;
    column-gap: 2rem;
  }

  .feature__list li:nth-last-child(2):nth-child(odd) {
    border-bottom: 0;
    padding-bottom: 0.15rem;
  }
}

.feature.is-in .feature__index {
  animation: feature-index-in 0.9s var(--ease) both;
}

@keyframes feature-index-in {
  from {
    opacity: 0;
    transform: translateY(18px) scale(0.92);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .feature.is-in .feature__index {
    animation: none;
  }
}

/* —— Scenes —— */
.scenes {
  padding-top: 0;
}

.scenes__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1.5rem 2rem;
}

.scenes__list li {
  padding-top: 1.15rem;
  border-top: 1px solid var(--line);
}

.scenes__list h3 {
  font-size: 1.15rem;
  color: var(--brand);
  margin-bottom: 0.4rem;
}

.scenes__list p {
  color: var(--muted);
  font-size: 0.98rem;
}

@media (min-width: 800px) {
  .scenes__list {
    grid-template-columns: 1fr 1fr;
  }
}

/* —— CTA —— */
.cta {
  padding-top: 0;
}

.cta__inner {
  border-radius: 1.5rem;
  padding: clamp(2.5rem, 6vw, 4rem);
  background:
    linear-gradient(135deg, rgba(31, 77, 58, 0.94), rgba(47, 107, 79, 0.88)),
    url("../assets/hero-home.jpg") center / cover;
  color: var(--white);
  text-align: center;
}

.cta__inner h2 {
  color: var(--white);
}

.cta__inner p {
  color: rgba(255, 255, 255, 0.88);
  margin: 0 auto 1.75rem;
}

.cta__inner .btn--primary {
  background: var(--white);
  color: var(--brand);
}

.cta__inner .btn--primary:hover {
  background: var(--brand-soft);
}

/* —— Footer —— */
.site-foot {
  padding: 2rem clamp(1.25rem, 4vw, 3.5rem) 2.75rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
  justify-content: space-between;
  align-items: baseline;
  border-top: 1px solid var(--line);
  color: var(--brand);
  font-family: var(--font-display);
  font-weight: 700;
}

.site-foot__meta {
  font-family: var(--font-body);
  font-weight: 400;
  color: var(--muted);
  font-size: 0.9rem;
}

/* —— Motion —— */
.reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.8s var(--ease), transform 0.8s var(--ease);
}

.reveal.is-in {
  opacity: 1;
  transform: none;
}

.reveal-delay-1 {
  transition-delay: 0.1s;
}

.reveal-delay-2 {
  transition-delay: 0.2s;
}

.reveal-delay-3 {
  transition-delay: 0.3s;
}

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

  .hero__media img {
    animation: none;
    transform: none;
  }

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