:root {
  color-scheme: light dark;
  --bg: #f7f8fc;
  --surface: #ffffff;
  --surface-muted: #f0f2f7;
  --text: #171923;
  --muted: #626978;
  --soft: #8d93a1;
  --border: #dfe3ec;
  --header: rgba(247, 248, 252, 0.84);
  --accent: #247ce5;
  --accent-strong: #1766c6;
  --accent-soft: #e7f1ff;
  --primary-bg: #1766c6;
  --primary-bg-hover: #1057aa;
  --primary-text: #ffffff;
  --cta-bg: #185fa8;
  --cta-muted: #d5e7f8;
  --shadow: 0 24px 70px rgba(29, 39, 65, 0.13);
  --max-width: 1180px;
  --ease-out: cubic-bezier(0.23, 1, 0.32, 1);
  --ease-in-out: cubic-bezier(0.77, 0, 0.175, 1);
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg: #161616;
  --surface: #212121;
  --surface-muted: #292929;
  --text: #f4f6fb;
  --muted: #a8aeba;
  --soft: #747a86;
  --border: #373737;
  --header: rgba(22, 22, 22, 0.86);
  --accent: #2c9cff;
  --accent-strong: #64b6ff;
  --accent-soft: rgba(44, 156, 255, 0.13);
  --primary-bg: #64b6ff;
  --primary-bg-hover: #83c5ff;
  --primary-text: #071521;
  --cta-bg: #164e7b;
  --cta-muted: #c2dcf1;
  --shadow: 0 28px 80px rgba(0, 0, 0, 0.34);
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #161616;
    --surface: #212121;
    --surface-muted: #292929;
    --text: #f4f6fb;
    --muted: #a8aeba;
    --soft: #747a86;
    --border: #373737;
    --header: rgba(22, 22, 22, 0.86);
    --accent: #2c9cff;
    --accent-strong: #64b6ff;
    --accent-soft: rgba(44, 156, 255, 0.13);
    --primary-bg: #64b6ff;
    --primary-bg-hover: #83c5ff;
    --primary-text: #071521;
    --cta-bg: #164e7b;
    --cta-muted: #c2dcf1;
    --shadow: 0 28px 80px rgba(0, 0, 0, 0.34);
  }
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background: var(--bg);
  color: var(--text);
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei UI", "Microsoft YaHei", "Segoe UI", sans-serif;
  font-kerning: normal;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  transition: background-color 180ms var(--ease-out), color 180ms var(--ease-out);
}
a { color: inherit; text-decoration: none; }
button, a { -webkit-tap-highlight-color: transparent; }
button { font: inherit; }
img { display: block; max-width: 100%; }
h1, h2, h3 { text-wrap: balance; }
p { text-wrap: pretty; }
::selection { background: var(--accent); color: var(--bg); }

.arrow-mark {
  position: relative;
  width: 14px;
  height: 14px;
  display: inline-block;
  flex: 0 0 auto;
  color: currentColor;
  transition: transform 160ms var(--ease-out);
}
.arrow-mark::before {
  content: "";
  position: absolute;
  left: 1px;
  top: 6px;
  width: 10px;
  height: 1.5px;
  background: currentColor;
  border-radius: 2px;
}
.arrow-mark::after {
  content: "";
  position: absolute;
  right: 1px;
  top: 4px;
  width: 5px;
  height: 5px;
  border-top: 1.5px solid currentColor;
  border-right: 1.5px solid currentColor;
  transform: rotate(45deg);
}
.arrow-external { transform: rotate(-45deg); }

.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 1000;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--text);
  color: var(--bg);
  transform: translateY(-160%);
}
.skip-link:focus { transform: translateY(0); }

.site-header {
  position: fixed;
  inset: 0 0 auto;
  z-index: 100;
  border-bottom: 1px solid transparent;
  background: var(--header);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  transition: background-color 180ms var(--ease-out), border-color 180ms var(--ease-out);
}
.site-header.scrolled { border-bottom-color: var(--border); }
.header-inner {
  width: min(calc(100% - 40px), var(--max-width));
  height: 72px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand { display: inline-flex; align-items: center; gap: 11px; font-weight: 700; letter-spacing: -0.015em; }
.brand-logo {
  flex: 0 0 34px;
  width: 34px;
  height: 34px;
  background: center / contain no-repeat url("assets/dl-logo-dark.png");
}
html[data-theme="dark"] .brand-logo { background-image: url("assets/dl-logo-white.png"); }
@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) .brand-logo { background-image: url("assets/dl-logo-white.png"); }
}
.main-nav { display: flex; align-items: center; gap: 30px; margin-left: auto; margin-right: 22px; }
.main-nav a { position: relative; display: inline-flex; align-items: center; gap: 7px; color: var(--muted); font-size: 13px; font-weight: 600; transition: color 150ms var(--ease-out); }
.main-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -9px;
  height: 2px;
  border-radius: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 160ms var(--ease-out);
}
.main-nav a:hover, .main-nav a:focus-visible, .main-nav a.is-active { color: var(--accent); }
.main-nav a.is-active::after { transform: scaleX(1); }
.header-actions { display: flex; align-items: center; gap: 8px; }
.theme-toggle, .menu-toggle {
  width: 40px;
  height: 40px;
  display: inline-grid;
  place-items: center;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: transform 140ms var(--ease-out), border-color 150ms var(--ease-out), background-color 150ms var(--ease-out);
}
.theme-toggle {
  width: auto;
  min-width: 68px;
  grid-template-columns: 20px auto;
  gap: 5px;
  padding: 0 10px;
}
.theme-toggle:hover { border-color: var(--accent); }
.theme-toggle:active, .menu-toggle:active { transform: scale(0.95); }
.theme-icon { font-size: 19px; line-height: 1; }
.theme-mode-text { font-size: 12px; font-weight: 700; line-height: 1; }
.menu-toggle { display: none; gap: 4px; padding: 10px; }
.menu-toggle span { width: 18px; height: 1.5px; background: currentColor; transition: transform 180ms var(--ease-out), opacity 120ms var(--ease-out); }

main { overflow: hidden; }
.hero {
  position: relative;
  width: min(calc(100% - 40px), var(--max-width));
  min-height: 720px;
  margin: 0 auto;
  padding: 136px 0 84px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(380px, 0.76fr);
  align-items: center;
  gap: clamp(64px, 8vw, 112px);
}
.section-index {
  margin: 0;
  color: var(--accent);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
}
.hero-copy { max-width: 640px; }
.hero h1 {
  margin: 0 0 24px;
  font-size: clamp(52px, 6vw, 76px);
  line-height: 1.06;
  letter-spacing: -0.025em;
  font-weight: 800;
}
.hero h1 em { color: var(--accent); font-style: normal; }
.hero-lead { max-width: 34em; margin: 0; color: var(--muted); font-size: 18px; line-height: 1.75; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; }
.button {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  padding: 0 21px;
  border: 1px solid transparent;
  border-radius: 9px;
  font-size: 14px;
  font-weight: 700;
  transition: transform 150ms var(--ease-out), background-color 150ms var(--ease-out), border-color 150ms var(--ease-out), color 150ms var(--ease-out);
}
.button:active { transform: scale(0.97); }
.button-primary { background: var(--primary-bg); color: var(--primary-text); }
.button-primary:hover { background: var(--primary-bg-hover); }
.button-secondary { border-color: var(--border); background: var(--surface); }
.button-secondary:hover { border-color: var(--accent); }
.button-light { background: #fff; color: #1665c2; }
.project-scope { align-self: center; border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.scope-identity { display: flex; align-items: center; gap: 14px; padding: 22px 0 24px; border-bottom: 1px solid var(--border); }
.scope-identity img { width: 44px; height: 44px; object-fit: contain; }
.scope-identity > span, .scope-list dd {
  min-width: 0;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}
.scope-identity strong, .scope-identity small, .scope-list strong, .scope-list small { display: block; }
.scope-identity strong { font-size: 16px; font-weight: 700; letter-spacing: -0.01em; }
.scope-identity small { margin-top: 3px; color: var(--muted); font-size: 12px; }
.scope-list { margin: 0; }
.scope-list > div { display: grid; grid-template-columns: 72px minmax(0, 1fr); gap: 18px; padding: 20px 0; border-top: 1px solid var(--border); }
.scope-list > div:first-child { border-top: 0; }
.scope-list dt { color: var(--soft); font-size: 12px; font-weight: 600; }
.scope-list dt, .scope-list dd { margin: 0; }
.scope-list strong { overflow-wrap: anywhere; font-size: 14px; font-weight: 700; line-height: 1.45; }
.scope-list small { margin-top: 4px; color: var(--muted); font-size: 12px; line-height: 1.5; }

.section, .site-footer { width: min(calc(100% - 40px), var(--max-width)); margin-inline: auto; }
.section { padding: 96px 0; scroll-margin-top: 56px; }
.section-heading { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 28px; align-items: end; margin-bottom: 42px; }
.section-heading h2, .cta h2 { margin: 0; font-size: clamp(32px, 4vw, 46px); font-weight: 700; line-height: 1.14; letter-spacing: -0.025em; }
.section-heading div > p { max-width: 52ch; margin: 13px 0 0; color: var(--muted); font-size: 16px; line-height: 1.7; }
.section-link { display: inline-flex; align-items: center; gap: 10px; margin-bottom: 6px; color: var(--muted); font-size: 13px; font-weight: 600; }
.section-link:hover { color: var(--accent); }

.project-grid { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: 20px; }
.project-card {
  grid-column: span 3;
  min-height: 340px;
  display: flex;
  flex-direction: column;
  padding: 30px 20px 25px;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  background: transparent;
  transition: transform 160ms var(--ease-out), border-color 160ms var(--ease-out), background-color 160ms var(--ease-out);
}
.project-card-primary { grid-column: span 6; padding: 32px; border: 1px solid var(--border); border-radius: 4px 16px 4px 4px; background: var(--surface); }
.project-topline { display: flex; align-items: center; justify-content: space-between; gap: 18px; }
.project-icon, .social-icon { display: grid; place-items: center; flex: 0 0 auto; background: var(--accent-soft); color: var(--accent); font-weight: 800; }
.project-icon { width: 48px; height: 48px; border-radius: 11px; font-size: 13px; }
.project-path { font-size: 11px; font-weight: 600; }
.project-path { color: var(--soft); }
.project-type { margin: 36px 0 10px; color: var(--soft); font-size: 11px; font-weight: 600; }
.project-card h3 { margin: 0 0 14px; overflow-wrap: anywhere; font-size: 24px; line-height: 1.25; letter-spacing: -0.02em; }
.project-card > p:not(.project-type) { margin: 0; color: var(--muted); font-size: 15px; line-height: 1.7; }
.card-action { display: inline-flex; align-items: center; gap: 12px; align-self: flex-start; margin-top: auto; padding-top: 30px; color: var(--accent); font-size: 13px; font-weight: 600; }
.card-action:hover { color: var(--accent-strong); }
.inline-actions { display: flex; align-items: end; gap: 18px; margin-top: auto; }
.inline-actions .card-action { margin-top: 0; }
.quiet-link { padding-bottom: 1px; color: var(--muted); font-size: 12px; text-decoration: underline; text-underline-offset: 4px; }
.quiet-link:hover { color: var(--accent); }

.contribute-note { margin-top: 32px; padding: 24px 0; display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; gap: 28px; border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.contribute-note p { max-width: 58ch; margin: 0; color: var(--muted); font-size: 14px; line-height: 1.7; }
.contribute-note p strong { margin-right: 0.45em; color: var(--text); font-weight: 700; }
.contribute-note > div { display: flex; flex-wrap: wrap; gap: 18px; }
.contribute-note a { display: inline-flex; align-items: center; gap: 8px; color: var(--accent); font-size: 13px; font-weight: 600; }

.contact-heading { grid-template-columns: 1fr; }
.contact-groups { border-top: 1px solid var(--border); }
.contact-group { display: grid; grid-template-columns: 180px 1fr; gap: 28px; padding: 34px 0; border-bottom: 1px solid var(--border); }
.contact-group-label span, .contact-group-label small { display: block; }
.contact-group-label span { font-size: 14px; font-weight: 700; }
.contact-group-label small { margin-top: 5px; color: var(--soft); font-size: 11px; font-weight: 400; }
.contact-links { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); column-gap: 24px; row-gap: 10px; }
.contact-links a { min-width: 0; display: grid; grid-template-columns: auto minmax(0, 1fr) auto; align-items: center; gap: 12px; padding: 15px 0; border-bottom: 1px solid var(--border); transition: color 150ms var(--ease-out), border-color 150ms var(--ease-out); }
.contact-links a:hover { color: var(--accent); border-color: var(--accent); }
.social-icon { width: 36px; height: 36px; border-radius: 9px; font-size: 10px; }
.social-icon-image { background: transparent; }
.social-icon-image img { width: 100%; height: 100%; object-fit: contain; border-radius: inherit; }
.social-icon-mail { border: 1px solid var(--border); background: transparent; }
.social-icon-mail svg { width: 19px; height: 19px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
html[data-theme="dark"] .social-icon-github img { filter: invert(1); }
@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) .social-icon-github img { filter: invert(1); }
}
.contact-links strong, .contact-links small { display: block; overflow: hidden; text-overflow: ellipsis; }
.contact-links strong { font-size: 13px; font-weight: 600; }
.contact-links small { margin-top: 3px; color: var(--soft); font-size: 11px; line-height: 1.5; white-space: nowrap; }
.contact-links b { color: var(--accent); }

.cta {
  width: min(calc(100% - 40px), var(--max-width));
  margin: 0 auto 36px;
  padding: 50px 54px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 36px;
  border-radius: 4px 16px 4px 4px;
  color: #fff;
  background: var(--cta-bg);
  box-shadow: 0 20px 50px rgba(20, 77, 128, 0.22);
}
.cta h2 { font-size: clamp(28px, 3.6vw, 40px); }
.cta div > p:last-child { margin: 12px 0 0; color: var(--cta-muted); font-size: 15px; line-height: 1.6; }

.site-footer { min-height: 150px; display: grid; grid-template-columns: 1fr auto 1fr; gap: 30px; align-items: center; color: var(--soft); }
.footer-brand { display: flex; align-items: center; gap: 12px; }
.footer-brand img { width: 30px; height: 30px; object-fit: contain; filter: grayscale(0.15); }
.footer-brand strong, .footer-brand small { display: block; }
.footer-brand strong { color: var(--text); font-size: 13px; }
.footer-brand small { margin-top: 2px; font-size: 11px; }
.footer-center { display: flex; align-items: center; justify-content: center; gap: 18px; font-size: 11px; }
.footer-center a { display: inline-flex; align-items: center; gap: 7px; }
.footer-center a:hover { color: var(--accent); }
.site-footer > p { justify-self: end; font-size: 11px; }

:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
.error-page { width: min(calc(100% - 40px), 720px); min-height: 100vh; margin: 0 auto; display: flex; flex-direction: column; align-items: flex-start; justify-content: center; }
.error-page img { width: 64px; height: 64px; object-fit: contain; margin-bottom: 34px; }
.error-page h1 { margin: 18px 0 12px; font-size: clamp(38px, 7vw, 58px); line-height: 1.08; letter-spacing: -0.03em; }
.error-page > p:not(.section-index) { max-width: 34em; margin: 0 0 30px; color: var(--muted); font-size: 17px; line-height: 1.7; }

@media (hover: hover) and (pointer: fine) {
  .button:hover { transform: translateY(-2px); }
  .project-card:hover { transform: translateY(-3px); border-color: var(--accent); background: var(--surface); }
  a:hover .arrow-mark:not(.arrow-external) { transform: translateX(2px); }
  a:hover .arrow-external { transform: translate(2px, -2px) rotate(-45deg); }
}

@media (max-width: 980px) {
  .main-nav { gap: 20px; }
  .hero { grid-template-columns: 1fr; min-height: auto; padding-top: 140px; }
  .hero-copy { max-width: 720px; }
  .project-scope { width: min(100%, 620px); justify-self: center; }
  .project-grid { grid-template-columns: 1fr 1fr; }
  .project-card { grid-column: auto; min-height: 320px; }
  .project-card-primary { grid-column: 1 / -1; min-height: 310px; }
  .contact-group { grid-template-columns: 120px 1fr; }
  .contact-links { grid-template-columns: 1fr 1fr; }
  .site-footer { grid-template-columns: 1fr auto; }
  .footer-center { grid-column: 1 / -1; grid-row: 2; justify-content: flex-start; }
}

@media (max-width: 760px) {
  .main-nav { position: absolute; top: 64px; left: 14px; right: 14px; display: flex; visibility: hidden; flex-direction: column; align-items: stretch; gap: 0; margin: 0; padding: 8px; border: 1px solid var(--border); border-radius: 12px; background: var(--surface); box-shadow: var(--shadow); opacity: 0; pointer-events: none; transform: translateY(-6px) scale(0.98); transform-origin: calc(100% - 30px) top; transition: opacity 180ms var(--ease-out), transform 180ms var(--ease-out), visibility 0s linear 180ms; }
  .main-nav.open { visibility: visible; opacity: 1; pointer-events: auto; transform: translateY(0) scale(1); transition-delay: 0s; }
  .main-nav a { padding: 13px 12px; }
  .main-nav a::after { left: 12px; right: 12px; bottom: 6px; transform-origin: left; }
  .menu-toggle { display: inline-grid; }
  .menu-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(5.5px) rotate(45deg); }
  .menu-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
  .menu-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-5.5px) rotate(-45deg); }
}

@media (max-width: 680px) {
  .header-inner, .hero, .section, .cta, .site-footer { width: min(calc(100% - 28px), var(--max-width)); }
  .header-inner { height: 64px; }
  .hero { padding: 112px 0 64px; gap: 48px; }
  .hero h1 { font-size: clamp(44px, 12vw, 54px); }
  .hero-lead { font-size: 16px; }
  .hero-actions .button { flex: 1 1 150px; }
  .scope-list > div { grid-template-columns: 58px minmax(0, 1fr); gap: 14px; }
  .section { padding: 74px 0; }
  .section-heading, .contact-heading { grid-template-columns: 1fr; margin-bottom: 34px; }
  .section-link { grid-column: 1; margin-top: -6px; }
  .project-grid { grid-template-columns: 1fr; }
  .project-card, .project-card-primary { grid-column: 1; min-height: 300px; padding: 26px; }
  .contribute-note { grid-template-columns: 1fr; gap: 16px; }
  .contact-group { grid-template-columns: 1fr; gap: 18px; }
  .contact-links { grid-template-columns: 1fr; }
  .cta { margin-bottom: 20px; padding: 38px 26px; flex-direction: column; align-items: flex-start; }
  .cta .button { width: 100%; }
  .site-footer { min-height: 240px; grid-template-columns: 1fr; padding: 34px 0; align-content: center; }
  .footer-center { grid-column: 1; grid-row: auto; flex-wrap: wrap; justify-content: flex-start; }
  .site-footer > p { justify-self: start; margin: 0; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; }
  .button, .theme-toggle, .menu-toggle, .project-card { transform: none !important; transition-property: color, background-color, border-color, opacity !important; transition-duration: 120ms !important; }
  .arrow-mark { transition-duration: 0.01ms !important; }
  .arrow-mark:not(.arrow-external) { transform: none !important; }
  .arrow-external { transform: rotate(-45deg) !important; }
  .main-nav { transform: none; transition: opacity 120ms var(--ease-out), visibility 0s linear 120ms; }
  .main-nav.open { transition-delay: 0s; }
  .main-nav a::after { transition-duration: 0.01ms; }
  .menu-toggle span { transition-duration: 0.01ms; }
}