:root {
  --ink: #121416;
  --ink-soft: #2a3136;
  --pine: #1f3a2e;
  --signal: #ff6b35;
  --signal-soft: rgba(255, 107, 53, 0.12);
  --ice: #8fd3ff;
  --mist: #f4f6f7;
  --paper: #fbfcfc;
  --grid: #c9d3d8;
  --grid-strong: #9aa6ac;
  --note: #f2e3b6;
  --tag: #5f6b73;
  --ok: #2e7d5a;
  --warn: #b45309;
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-display: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Arial Narrow", Arial, sans-serif;
  --font-serif: "Songti SC", "Source Han Serif SC", "Noto Serif CJK SC", SimSun, Georgia, serif;
  --font-mono: ui-monospace, SFMono-Regular, "Cascadia Mono", "Roboto Mono", Menlo, Consolas, monospace;
  --shell-max: 1240px;
  --note-radius: 6px;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body,
h1, h2, h3, h4, h5, p, ul, ol, li, figure, blockquote, dl, dd, fieldset {
  margin: 0;
}

ul,
ol {
  padding: 0;
  list-style: none;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  background-color: var(--mist);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.72;
  letter-spacing: 0.008em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-wrap: break-word;
}

main {
  flex: 1 0 auto;
  display: block;
  scroll-margin-top: 8rem;
}

img,
svg {
  max-width: 100%;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.16;
  letter-spacing: -0.015em;
  color: var(--ink);
}

h1 { font-size: clamp(2rem, 4.4vw, 3.5rem); font-weight: 900; }
h2 { font-size: clamp(1.45rem, 2.5vw, 2.1rem); }
h3 { font-size: clamp(1.1rem, 1.5vw, 1.32rem); }
h4 { font-size: 1rem; letter-spacing: 0.02em; }

p { text-wrap: pretty; }

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

p a,
.prose a {
  color: var(--pine);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}

p a:hover,
.prose a:hover {
  color: var(--signal);
}

:focus-visible {
  outline: 2px solid var(--ice);
  outline-offset: 2px;
  box-shadow: 0 0 0 4px rgba(18, 20, 22, 0.45);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* ---------- 容器 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding-inline: clamp(1rem, 4vw, 2.5rem);
}

.section {
  padding-block: clamp(2.5rem, 5.5vw, 4.5rem);
}

/* ---------- 跳转链接 ---------- */
.skip-link {
  position: absolute;
  left: 0.75rem;
  top: -4rem;
  z-index: 200;
  padding: 0.6rem 1.05rem;
  background-color: var(--signal);
  color: #1a0c05;
  font-size: 0.9rem;
  font-weight: 700;
  border: 2px solid #1a0c05;
  transition: top 0.18s ease;
}

.skip-link:focus {
  top: 0.75rem;
}

/* ---------- 头部 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background-color: var(--paper);
  border-bottom: 1px solid var(--grid);
}

.header-utility {
  background-color: var(--pine);
  border-bottom: 1px solid rgba(201, 211, 216, 0.22);
}

.utility-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem 0.9rem;
  min-height: 2.1rem;
  padding-block: 0.35rem;
  font-family: var(--font-mono);
  font-size: 0.71rem;
  letter-spacing: 0.08em;
}

.utility-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.42rem;
  color: #f4f6f7;
  font-weight: 500;
  white-space: nowrap;
}

.utility-mark {
  color: var(--signal);
  font-size: 0.78rem;
  line-height: 1;
  transform: translateY(-0.5px);
}

.utility-note {
  color: #a9bbb2;
  padding-left: 0.9rem;
  border-left: 1px solid rgba(201, 211, 216, 0.3);
  white-space: nowrap;
}

.utility-links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.15rem 1.05rem;
  margin-left: auto;
}

.utility-links a {
  color: #9fc7dc;
  padding-block: 0.1rem;
  border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.utility-links a:hover,
.utility-links a:focus-visible {
  color: var(--ice);
  border-bottom-color: var(--ice);
}

.header-main {
  background-color: var(--paper);
}

.header-main-inner {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  min-height: 4.15rem;
  padding-block: 0.55rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  flex: 0 0 auto;
}

.brand-glyph {
  position: relative;
  display: block;
  width: 1.55rem;
  height: 1.55rem;
  flex: none;
  border: 1.5px solid var(--ink);
}

.brand-glyph::before,
.brand-glyph::after {
  content: "";
  position: absolute;
  background-color: var(--signal);
}

.brand-glyph::before {
  left: 50%;
  top: -5px;
  bottom: -5px;
  width: 1.5px;
  transform: translateX(-50%);
}

.brand-glyph::after {
  top: 50%;
  left: -5px;
  right: -5px;
  height: 1.5px;
  transform: translateY(-50%);
}

.brand-text {
  display: block;
  min-width: 0;
}

.brand-name {
  display: block;
  font-family: var(--font-display);
  font-size: 1.14rem;
  font-weight: 900;
  line-height: 1.12;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.brand-coord {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.63rem;
  line-height: 1.5;
  letter-spacing: 0.14em;
  color: var(--tag);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.5rem;
  margin-left: auto;
  padding: 0.42rem 0.7rem;
  background-color: transparent;
  border: 1px solid var(--grid-strong);
  border-radius: 0;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  cursor: pointer;
  transition: border-color 0.18s ease, background-color 0.18s ease;
}

.nav-toggle:hover {
  border-color: var(--ink);
  background-color: rgba(18, 20, 22, 0.05);
}

.nav-toggle-bar {
  position: relative;
  display: block;
  width: 1rem;
  height: 2px;
  background-color: var(--ink);
}

.nav-toggle-bar::before,
.nav-toggle-bar::after {
  content: "";
  position: absolute;
  left: 0;
  width: 1rem;
  height: 2px;
  background-color: var(--ink);
  transition: transform 0.18s ease, opacity 0.18s ease;
}

.nav-toggle-bar::before { top: -5px; }
.nav-toggle-bar::after { top: 5px; }

.nav-toggle[aria-expanded="true"] .nav-toggle-bar { background-color: transparent; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::before { transform: translateY(5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::after { transform: translateY(-5px) rotate(-45deg); }

.nav-toggle-label {
  line-height: 1;
}

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

.nav-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.1rem;
}

.nav-link {
  display: inline-block;
  padding: 0.5rem 0.72rem;
  color: var(--ink-soft);
  font-size: 0.94rem;
  font-weight: 500;
  border-bottom: 2px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease, background-color 0.18s ease;
}

.nav-link:hover {
  color: var(--ink);
  border-bottom-color: var(--signal);
  background-color: var(--signal-soft);
}

.nav-link[aria-current="page"] {
  color: var(--ink);
  font-weight: 800;
  border-bottom-color: var(--signal);
  background-color: var(--signal-soft);
}

.header-progress {
  height: 2px;
  background-color: rgba(201, 211, 216, 0.5);
  overflow: hidden;
}

.progress-bar {
  display: block;
  width: 0;
  height: 100%;
  background-image: linear-gradient(90deg, var(--signal), var(--ice));
  transition: width 0.12s linear;
}

/* ---------- 页脚 ---------- */
.site-footer {
  margin-top: auto;
  padding-top: clamp(2.5rem, 5vw, 3.75rem);
  color: #b9c4c9;
  background-color: var(--ink);
  background-image:
    linear-gradient(to right, rgba(143, 211, 255, 0.07) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(143, 211, 255, 0.07) 1px, transparent 1px);
  background-size: 72px 72px;
  border-top: 3px solid var(--signal);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.35fr;
  gap: 2rem clamp(1.25rem, 3.5vw, 3rem);
  padding-bottom: clamp(2rem, 4vw, 3rem);
}

.footer-brand {
  min-width: 0;
}

.footer-logo {
  font-family: var(--font-display);
  font-size: 1.32rem;
  font-weight: 900;
  letter-spacing: -0.01em;
  color: #f4f6f7;
}

.footer-tag {
  margin-top: 0.55rem;
  max-width: 24ch;
  font-family: var(--font-serif);
  font-size: 0.95rem;
  line-height: 1.7;
  color: #93a2a8;
}

.footer-meta {
  margin-top: 1rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  color: #6e7c82;
}

.footer-col {
  min-width: 0;
}

.footer-title {
  margin-bottom: 0.85rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--ice);
}

.footer-list li {
  margin-top: 0.5rem;
  font-size: 0.9rem;
  line-height: 1.6;
  color: #b9c4c9;
}

.footer-list li:first-child {
  margin-top: 0;
}

.footer-list a {
  color: #c6d1d6;
  border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.footer-list a:hover,
.footer-list a:focus-visible {
  color: var(--ice);
  border-bottom-color: var(--ice);
}

.footer-contact li {
  color: #a8b5ba;
}

.footer-base {
  background-color: rgba(0, 0, 0, 0.32);
  border-top: 1px solid rgba(201, 211, 216, 0.18);
}

.footer-base-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 1.5rem;
  padding-block: 1rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  color: #7b878d;
}

.footer-copy {
  color: #a8b5ba;
}

.footer-note {
  color: #6e7c82;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1rem;
  margin-left: auto;
}

.footer-legal a {
  color: #a8b5ba;
  border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.footer-legal a:hover,
.footer-legal a:focus-visible {
  color: var(--ice);
  border-bottom-color: var(--ice);
}

.footer-icp {
  color: #7b878d;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.72rem 1.25rem;
  border: 1px solid transparent;
  border-radius: 0;
  font-family: var(--font-sans);
  font-size: 0.92rem;
  font-weight: 600;
  line-height: 1.2;
  text-align: center;
  cursor: pointer;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}

.btn-primary {
  background-color: var(--signal);
  border-color: var(--signal);
  color: #1a0c05;
}

.btn-primary:hover {
  background-color: #ff8355;
  border-color: #ff8355;
}

.btn-ghost {
  background-color: transparent;
  border-color: var(--grid-strong);
  color: var(--ink);
}

.btn-ghost:hover {
  border-color: var(--ink);
  background-color: rgba(18, 20, 22, 0.05);
}

.btn-ice {
  background-color: transparent;
  border-color: rgba(143, 211, 255, 0.45);
  color: var(--ice);
}

.btn-ice:hover {
  background-color: rgba(143, 211, 255, 0.14);
  border-color: var(--ice);
}

/* ---------- 面包屑 ---------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem;
  padding-block: 1.1rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  color: var(--tag);
}

.breadcrumb li {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.breadcrumb li + li::before {
  content: "/";
  color: var(--grid-strong);
}

.breadcrumb a {
  color: var(--tag);
  border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.breadcrumb a:hover,
.breadcrumb a:focus-visible {
  color: var(--ink);
  border-bottom-color: var(--signal);
}

/* ---------- 排版与通用块 ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  font-family: var(--font-mono);
  font-size: 0.69rem;
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--tag);
}

.eyebrow::before {
  content: "";
  width: 0.85rem;
  height: 1px;
  background-color: var(--signal);
}

.lede {
  max-width: 58ch;
  font-size: clamp(1rem, 1.35vw, 1.14rem);
  line-height: 1.75;
  color: #39444a;
}

.prose p + p {
  margin-top: 0.9rem;
}

.prose h2,
.prose h3 {
  margin-top: 1.8rem;
  margin-bottom: 0.6rem;
}

.grid {
  display: grid;
  gap: clamp(1rem, 2.4vw, 2rem);
}

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

.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.18rem 0.55rem;
  border: 1px solid var(--grid);
  border-radius: 0;
  background-color: var(--paper);
  font-family: var(--font-mono);
  font-size: 0.67rem;
  letter-spacing: 0.1em;
  color: var(--tag);
  white-space: nowrap;
}

.tag-signal {
  border-color: var(--signal);
  background-color: var(--signal-soft);
  color: #8a3512;
}

.tag-ice {
  border-color: rgba(143, 211, 255, 0.7);
  background-color: rgba(143, 211, 255, 0.16);
  color: #1c5a78;
}

.note {
  position: relative;
  padding: 0.9rem 1.1rem;
  border-left: 3px solid var(--signal);
  border-radius: 2px var(--note-radius) var(--note-radius) 2px;
  background-color: var(--note);
  color: #3b3011;
  font-size: 0.92rem;
  line-height: 1.7;
}

.note::before {
  content: "";
  position: absolute;
  top: 0.6rem;
  left: -6px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background-color: var(--signal);
  box-shadow: 0 0 0 2px rgba(255, 107, 53, 0.28);
}

/* ---------- 图片容器基础 ---------- */
.img-frame {
  position: relative;
  display: block;
  width: 100%;
  overflow: hidden;
  border: 1px solid var(--grid);
  background-color: var(--mist);
  background-image:
    linear-gradient(to right, rgba(201, 211, 216, 0.6) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(201, 211, 216, 0.6) 1px, transparent 1px);
  background-size: 28px 28px;
}

.img-frame::before {
  content: "";
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 1px;
  z-index: 0;
  background-color: rgba(255, 107, 53, 0.4);
  pointer-events: none;
}

.img-frame::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 0;
  right: 0;
  height: 1px;
  z-index: 0;
  background-color: rgba(255, 107, 53, 0.4);
  pointer-events: none;
}

.img-frame img {
  position: relative;
  z-index: 1;
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.img-frame--16x9 { aspect-ratio: 16 / 9; }
.img-frame--4x3 { aspect-ratio: 4 / 3; }
.img-frame--1x1 { aspect-ratio: 1 / 1; }
.img-frame--21x9 { aspect-ratio: 21 / 9; }

.img-caption {
  margin-top: 0.55rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  color: var(--tag);
}

/* ---------- 显现协议 ---------- */
html[data-js="true"] [data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.45s ease, transform 0.45s ease;
}

html[data-js="true"] [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .footer-grid {
    grid-template-columns: 1.4fr 1fr 1fr;
  }
  .footer-contact {
    grid-column: 1 / -1;
  }
  .footer-contact .footer-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem 1.75rem;
  }
  .footer-contact .footer-list li {
    margin-top: 0;
  }
}

@media (max-width: 900px) {
  .header-main-inner {
    flex-wrap: wrap;
    row-gap: 0.5rem;
    padding-block: 0.55rem;
  }

  .nav-toggle {
    display: inline-flex;
    margin-left: auto;
  }

  .primary-nav {
    display: none;
    order: 3;
    width: 100%;
    margin-left: 0;
    padding-top: 0.4rem;
    border-top: 1px solid var(--grid);
  }

  .primary-nav[data-open="true"] {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .nav-link {
    display: block;
    padding: 0.66rem 0.75rem;
    border-bottom: 1px solid var(--grid);
    border-left: 2px solid transparent;
  }

  .nav-link:hover,
  .nav-link:focus-visible {
    border-bottom-color: var(--grid);
    border-left-color: var(--signal);
  }

  .nav-link[aria-current="page"] {
    border-bottom-color: var(--grid);
    border-left-color: var(--signal);
  }

  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }

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

  .footer-brand {
    grid-column: 1 / -1;
  }

  .footer-legal {
    margin-left: 0;
  }
}

@media (max-width: 720px) {
  .utility-note {
    display: none;
  }

  .utility-inner {
    font-size: 0.66rem;
    letter-spacing: 0.06em;
  }

  .utility-links {
    gap: 0.15rem 0.8rem;
  }

  .header-main-inner {
    min-height: 3.6rem;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 1.75rem;
  }

  .footer-base-inner {
    font-size: 0.66rem;
    gap: 0.35rem 1rem;
  }

  .footer-legal {
    width: 100%;
  }
}

@media (max-width: 460px) {
  .brand-name { font-size: 1.02rem; }
  .brand-coord { font-size: 0.58rem; letter-spacing: 0.1em; }
  .brand-glyph { width: 1.35rem; height: 1.35rem; }
  .nav-toggle-label { display: none; }
  .footer-tag { max-width: none; }
}

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

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

  html[data-js="true"] [data-reveal] {
    opacity: 1;
    transform: none;
  }
}