:root {
  --black: #050505;
  --ink: #111111;
  --panel: #181818;
  --line: #2d2d2d;
  --soft-line: #e6e6e6;
  --white: #ffffff;
  --paper: #f7f7f4;
  --muted: #767676;
  --accent: #df7655;
  --signal: #14c99a;
  --radius: 8px;
  --max: 1180px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
  line-height: 1.65;
}

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

/* picture 默认是 inline，作为 grid/flex 子项会撑不满列宽 */
picture {
  display: block;
}

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

.site-header {
  position: fixed;
  z-index: 30;
  top: 0;
  left: 0;
  right: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
  padding: 0 clamp(20px, 4vw, 56px);
  color: var(--white);
  transition: background 180ms ease, border-color 180ms ease;
}

.site-header.solid {
  background: rgba(5, 5, 5, 0.92);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(16px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.brand-mark {
  width: 34px;
  height: 34px;
  flex: none;
}

.brand strong,
.brand small {
  display: block;
  line-height: 1.1;
}

.brand small {
  margin-top: 4px;
  color: rgba(255, 255, 255, 0.62);
  font-size: 12px;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 26px;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.78);
}

.site-nav a {
  white-space: nowrap;
}

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

.nav-admin {
  padding: 8px 14px;
  border: 1px solid rgba(255, 255, 255, 0.28);
  border-radius: 999px;
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border: 0;
  background: transparent;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  margin: 6px auto;
  background: var(--white);
}

.hero {
  position: relative;
  min-height: 92vh;
  display: flex;
  align-items: flex-end;
  overflow: hidden;
  background: var(--black);
  color: var(--white);
}

/* 首屏背景图外层的 picture 需要自己撑满，否则会成为 flex 子项挤压布局 */
.hero > picture {
  position: absolute;
  inset: 0;
}

.hero-bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  opacity: 0.62;
}

.hero-shade {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, rgba(0, 0, 0, 0.92), rgba(0, 0, 0, 0.42) 52%, rgba(0, 0, 0, 0.72)),
    linear-gradient(0deg, rgba(0, 0, 0, 0.88), transparent 46%);
}

.hero-content {
  position: relative;
  width: min(920px, calc(100% - 40px));
  margin: 0 auto;
  padding: 150px 0 118px;
}

.eyebrow,
.section-kicker {
  margin: 0 0 14px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(42px, 8vw, 88px);
  line-height: 1.05;
  letter-spacing: 0;
}

.hero-copy {
  max-width: 720px;
  margin: 26px 0 0;
  color: rgba(255, 255, 255, 0.78);
  font-size: clamp(17px, 2vw, 21px);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 20px;
  border-radius: 999px;
  font-weight: 700;
  transition: transform 160ms ease, background 160ms ease, color 160ms ease;
}

.button:hover {
  transform: translateY(-1px);
}

.button-light {
  background: var(--white);
  color: var(--black);
}

.button-ghost {
  border: 1px solid rgba(255, 255, 255, 0.35);
  color: var(--white);
}

.section {
  padding: clamp(72px, 9vw, 126px) 0;
  background: var(--paper);
}

.section-light {
  background: var(--white);
}

.section-dark {
  background: var(--black);
  color: var(--white);
}

.container {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

.intro {
  padding-top: clamp(48px, 6vw, 82px);
  padding-bottom: clamp(48px, 6vw, 82px);
}

.intro-grid,
.about-grid,
.contact-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: clamp(28px, 6vw, 82px);
  align-items: start;
}

h2 {
  margin: 0;
  font-size: clamp(32px, 5vw, 58px);
  line-height: 1.12;
  letter-spacing: 0;
}

h3 {
  margin: 0;
  font-size: 21px;
  line-height: 1.25;
  letter-spacing: 0;
}

p {
  margin: 0;
}

.section-head {
  max-width: 820px;
  margin-bottom: 36px;
}

.section-head p:last-child {
  margin-top: 18px;
  color: var(--muted);
  font-size: 18px;
}

.scene-grid,
.capability-grid,
.version-grid,
.screen-grid {
  display: grid;
  gap: 16px;
}

.scene-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.capability-grid,
.version-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.text-card,
.dark-card,
.screen-card {
  border-radius: var(--radius);
}

.text-card {
  min-height: 214px;
  padding: 24px;
  border: 1px solid var(--soft-line);
  background: rgba(255, 255, 255, 0.52);
}

.card-index {
  display: block;
  margin-bottom: 32px;
  color: var(--muted);
  font-weight: 800;
}

.text-card p,
.dark-card p,
.screen-card p,
.about-grid p,
.contact-grid p,
.intro-grid p {
  margin-top: 16px;
  color: #5f5f5f;
}

.dark-card {
  min-height: 188px;
  padding: 28px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: var(--panel);
}

.dark-card p,
.about-grid p {
  color: rgba(255, 255, 255, 0.66);
}

.highlight-card {
  border-color: rgba(223, 118, 85, 0.68);
}

.screen-feature {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(300px, 0.65fr);
  gap: 28px;
  align-items: center;
  margin-bottom: 18px;
}

.screen-feature img,
.screen-card img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border: 1px solid var(--soft-line);
  border-radius: var(--radius);
  background: var(--black);
}

.screen-feature h3 {
  font-size: clamp(28px, 4vw, 44px);
}

.screen-feature p:last-child {
  margin-top: 18px;
  color: #555;
  font-size: 18px;
}

.screen-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.screen-card {
  overflow: hidden;
  border: 1px solid var(--soft-line);
  background: var(--white);
}

.screen-card div {
  padding: 22px;
}

.version-card {
  min-height: 190px;
  background: var(--white);
}

.about-section {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.contact-panel {
  display: grid;
  gap: 14px;
  padding: 28px;
  border: 1px solid var(--soft-line);
  border-radius: var(--radius);
  background: var(--white);
  font-style: normal;
  font-size: clamp(18px, 3vw, 26px);
  font-weight: 700;
}

.contact-panel span {
  color: #555;
  font-size: 18px;
  font-weight: 500;
}

.site-footer {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 18px;
  padding: 24px clamp(20px, 4vw, 56px);
  background: var(--black);
  color: rgba(255, 255, 255, 0.58);
  font-size: 14px;
}

.footer-beian {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 18px;
}

.footer-beian a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: inherit;
}

.footer-beian a:hover {
  color: rgba(255, 255, 255, 0.9);
  text-decoration: underline;
}

.admin-page {
  min-height: 100vh;
  background: var(--black);
  color: var(--white);
}

.admin-main {
  padding: 118px 20px 56px;
}

.admin-shell {
  display: grid;
  grid-template-columns: minmax(280px, 0.78fr) minmax(0, 1.22fr);
  gap: 32px;
  width: min(1080px, 100%);
  margin: 0 auto;
}

.admin-intro,
.admin-form {
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: var(--radius);
  background: var(--panel);
  padding: 28px;
}

.admin-intro h1 {
  margin: 0;
  font-size: clamp(34px, 5vw, 56px);
  line-height: 1.1;
}

.admin-intro p:last-child {
  margin-top: 18px;
  color: rgba(255, 255, 255, 0.65);
}

.admin-form {
  display: grid;
  gap: 18px;
  position: relative;
}

.admin-form::after {
  content: "已保存";
  position: absolute;
  right: 24px;
  top: 20px;
  opacity: 0;
  color: var(--signal);
  font-weight: 700;
  transition: opacity 160ms ease;
}

.admin-form.saved::after {
  opacity: 1;
}

.admin-form label {
  display: grid;
  gap: 8px;
  color: rgba(255, 255, 255, 0.72);
  font-size: 14px;
}

.admin-form input,
.admin-form textarea {
  width: 100%;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: var(--radius);
  background: #101010;
  color: var(--white);
  padding: 12px 14px;
  font: inherit;
  resize: vertical;
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.admin-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 8px;
}

.dark-ghost {
  color: var(--white);
  background: transparent;
}

@media (max-width: 920px) {
  .nav-toggle {
    display: block;
  }

  .site-nav {
    position: fixed;
    top: 72px;
    left: 16px;
    right: 16px;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 12px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius);
    background: rgba(5, 5, 5, 0.96);
  }

  .site-nav.open,
  .site-nav.static-nav {
    display: flex;
  }

  .site-nav a {
    padding: 12px;
  }

  .intro-grid,
  .about-grid,
  .contact-grid,
  .screen-feature,
  .admin-shell {
    grid-template-columns: 1fr;
  }

  .scene-grid,
  .capability-grid,
  .version-grid,
  .screen-grid,
  .form-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .site-header {
    height: 64px;
    padding: 0 16px;
  }

  .brand small {
    display: none;
  }

  .hero {
    min-height: 88vh;
  }

  .hero-content {
    width: calc(100% - 32px);
    padding-bottom: 78px;
  }

  .hero-actions,
  .admin-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .section {
    padding: 62px 0;
  }

  .container {
    width: calc(100% - 32px);
  }

  .text-card,
  .dark-card,
  .contact-panel,
  .admin-intro,
  .admin-form {
    padding: 20px;
  }

  .site-footer {
    flex-direction: column;
  }
}