:root {
  --paper: #ffffff;
  --paper-2: #f5f5f5;
  --paper-3: #ececec;
  --ink: #0a0a0a;
  --ink-soft: #4a4a4a;
  --muted: #8a8a8a;
  --faint: #b3b3b3;
  --line: #e6e6e6;
  --line-strong: #cccccc;
  --accent: #0a0a0a;
  --accent-deep: #000000;
  --accent-soft: #e6e6e6;
  --shadow-sm: 0 6px 18px rgba(0, 0, 0, 0.07);
  --shadow-md: 0 16px 40px rgba(0, 0, 0, 0.12);
  --shadow-lg: 0 30px 80px rgba(0, 0, 0, 0.16);
  --ease: cubic-bezier(.16, 1, .3, 1);
  --ease-spring: cubic-bezier(.34, 1.56, .64, 1);
  --serif: "Lora", "Noto Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --sans: "Segoe UI", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --mono: "Cascadia Code", "Consolas", "SF Mono", "Menlo", monospace;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.75;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

::selection { background: rgba(0, 0, 0, 0.2); }

::-webkit-scrollbar { width: 11px; height: 11px; }
::-webkit-scrollbar-track { background: var(--paper); }
::-webkit-scrollbar-thumb { background: var(--line-strong); border-radius: 8px; border: 3px solid var(--paper); }
::-webkit-scrollbar-thumb:hover { background: var(--faint); }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }

.container { max-width: 1160px; margin: 0 auto; padding: 0 26px; }
.wrap-narrow { max-width: 920px; margin: 0 auto; padding: 0 26px; }
.mono { font-family: var(--mono); }


.grain {
  position: fixed; inset: -60%;
  z-index: 9999; pointer-events: none; opacity: 0.05;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  animation: grainShift 9s steps(8) infinite;
}
@keyframes grainShift {
  0%, 100% { transform: translate(0, 0); }
  20% { transform: translate(-2%, 1.5%); }
  40% { transform: translate(1.5%, -2%); }
  60% { transform: translate(-1%, -1%); }
  80% { transform: translate(2%, 2%); }
}

.ambient { position: fixed; inset: 0; z-index: -2; pointer-events: none; overflow: hidden; }
.ambient .orb { position: absolute; border-radius: 50%; filter: blur(90px); opacity: .5; will-change: transform; }
.ambient .o1 { width: 56vmax; height: 56vmax; left: -18vmax; top: -20vmax; background: radial-gradient(circle, rgba(0,0,0,0.06), transparent 62%); animation: drift1 34s ease-in-out infinite alternate; }
.ambient .o2 { width: 46vmax; height: 46vmax; right: -16vmax; top: 40vmax; background: radial-gradient(circle, rgba(0,0,0,0.05), transparent 60%); animation: drift2 40s ease-in-out infinite alternate; }
.ambient .o3 { width: 42vmax; height: 42vmax; left: 18vmax; bottom: -24vmax; background: radial-gradient(circle, rgba(0,0,0,0.04), transparent 62%); animation: drift3 46s ease-in-out infinite alternate; }
@keyframes drift1 { from { transform: translate3d(0,0,0) scale(1); } to { transform: translate3d(5vmax,4vmax,0) scale(1.14); } }
@keyframes drift2 { from { transform: translate3d(0,0,0) scale(1.06); } to { transform: translate3d(-4vmax,-5vmax,0) scale(.94); } }
@keyframes drift3 { from { transform: translate3d(0,0,0) scale(.92); } to { transform: translate3d(3vmax,-5vmax,0) scale(1.1); } }

.hairline {
  position: fixed; top: 0; left: 0; right: 0; height: 2px; z-index: 95;
  background: linear-gradient(90deg, transparent, rgba(0,0,0,.4) 25%, var(--accent) 50%, rgba(0,0,0,.4) 75%, transparent);
  opacity: .8;
}


.preloader {
  position: fixed; inset: 0; z-index: 9990;
  display: grid; place-items: center;
  background: var(--paper);
  transition: transform .95s var(--ease), visibility .95s;
}
.preloader.done { transform: translateY(-101%); visibility: hidden; }
.preloader .pl-inner { text-align: center; }
.preloader .pl-q {
  width: 58px; height: 58px; margin: 0 auto; border-radius: 12px;
  background: var(--ink); color: var(--paper);
  display: grid; place-items: center;
  font-family: var(--serif); font-style: italic; font-weight: 700; font-size: 30px;
  transform: rotate(-8deg); opacity: 0;
  animation: plQ 1s var(--ease-spring) forwards;
}
@keyframes plQ { to { opacity: 1; transform: rotate(0deg) translateY(0); } }
.preloader .pl-line { width: 180px; height: 2px; margin: 20px auto 0; border-radius: 99px; overflow: hidden; background: var(--line); }
.preloader .pl-line i { display: block; height: 100%; width: 0; background: var(--ink); transition: width .25s var(--ease); }
.preloader .pl-pct { margin-top: 12px; font-family: var(--mono); font-size: 11px; letter-spacing: .3em; color: var(--faint); font-variant-numeric: tabular-nums; }
.preloader .pl-name { margin-top: 6px; font-family: var(--serif); font-style: italic; font-size: 13px; letter-spacing: 2px; color: var(--muted); opacity: 0; animation: plFade .8s ease .5s forwards; }
@keyframes plFade { to { opacity: 1; } }


.preloader { display: none !important; }
body { animation: qapiPageIn .55s var(--ease) .05s both; }
@keyframes qapiPageIn { from { opacity: 0; } to { opacity: 1; } }


.scroll-progress {
  position: fixed; top: 0; left: 0; right: 0; height: 2px; z-index: 120;
  background: linear-gradient(90deg, var(--accent-soft), var(--accent), var(--accent-deep));
  transform: scaleX(0); transform-origin: 0 0; will-change: transform;
}


.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 90;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: blur(18px) saturate(1.4);
  -webkit-backdrop-filter: blur(18px) saturate(1.4);
  border-bottom: 1px solid var(--line);
  transform: translateY(0);
  transition: transform .45s var(--ease), background .3s;
  opacity: 0; animation: navIn .8s var(--ease) .1s forwards;
}
@keyframes navIn { from { opacity: 0; transform: translateY(-14px); } to { opacity: 1; transform: translateY(0); } }
.nav.scrolled { background: rgba(255, 255, 255, 0.94); }
.nav.hide-nav { transform: translateY(-100%); }

.nav-in { max-width: 1160px; margin: 0 auto; padding: 0 26px; height: 68px; display: flex; align-items: center; gap: 20px; }

.logo { display: flex; align-items: center; gap: 11px; flex-shrink: 0; }
.logo-badge {
  width: 34px; height: 34px; border-radius: 6px;
  display: grid; place-items: center;
  background: #ffffff; color: #4361ee;
  font-family: var(--serif); font-style: italic; font-weight: 700;
  font-size: 18px; letter-spacing: -0.5px;
  transition: transform .5s var(--ease-spring);
}
.logo:hover .logo-badge { transform: rotate(-10deg) scale(1.06); }
.logo-text { display: flex; flex-direction: column; line-height: 1.1; }
.logo-text strong { font-family: var(--serif); font-size: 19px; font-weight: 600; letter-spacing: 0.4px; }
.logo-text em { font-style: normal; font-size: 10px; letter-spacing: 2.4px; text-transform: uppercase; color: var(--muted); margin-top: 2px; }

.nav-links { display: flex; align-items: center; gap: 2px; flex: 1; min-width: 0; justify-content: center; }
.nav-links a { position: relative; padding: 8px 13px; border-radius: 7px; font-size: 13.5px; color: var(--ink-soft); white-space: nowrap; transition: color .2s, background .2s; }
.nav-links a::after { content: ""; position: absolute; left: 13px; right: 13px; bottom: 3px; height: 1.5px; border-radius: 2px; background: var(--accent); transform: scaleX(0); transform-origin: 0 50%; transition: transform .35s var(--ease); }
.nav-links a:hover { color: var(--ink); background: var(--paper-2); }
.nav-links a:hover::after { transform: scaleX(1); }
.nav-links a.active { color: var(--accent-deep); font-weight: 600; background: var(--accent-soft); }
.nav-links a.active::after { transform: scaleX(1); }


.nav-group { position: relative; }
.nav-group summary { list-style: none; cursor: pointer; padding: 8px 13px; border-radius: 7px; font-size: 13.5px; color: var(--ink-soft); display: flex; align-items: center; gap: 6px; white-space: nowrap; transition: color .2s, background .2s; }
.nav-group summary::-webkit-details-marker { display: none; }
.nav-group summary:hover { color: var(--ink); background: var(--paper-2); }
.nav-group[open] summary { color: var(--accent-deep); font-weight: 600; background: var(--accent-soft); }
.nav-group .arr { font-size: 10px; transition: transform .25s var(--ease); }
.nav-group[open] .arr { transform: rotate(180deg); }
.nav-group-body { position: absolute; top: calc(100% + 8px); left: 0; min-width: 172px; padding: 6px; display: flex; flex-direction: column; gap: 2px; background: var(--paper); border: 1px solid var(--line-strong); border-radius: 10px; box-shadow: var(--shadow-md); z-index: 100; }
.nav-group-body a { padding: 8px 12px; border-radius: 7px; font-size: 13.5px; color: var(--ink-soft); white-space: nowrap; }
.nav-group-body a:hover { color: var(--ink); background: var(--paper-2); }
.nav-group-body a.active { color: var(--accent-deep); font-weight: 600; background: var(--accent-soft); }


.nav-group-mobile summary { list-style: none; cursor: pointer; padding: 11px 12px; border-radius: 9px; color: var(--ink-soft); font-size: 14.5px; display: flex; align-items: center; justify-content: space-between; transition: color .2s, background .2s; }
.nav-group-mobile summary::-webkit-details-marker { display: none; }
.nav-group-mobile summary:hover { color: var(--ink); background: var(--paper-2); }
.nav-group-mobile[open] summary { color: var(--accent-deep); font-weight: 600; background: var(--accent-soft); }
.nav-group-mobile .arr { font-size: 10px; transition: transform .25s var(--ease); }
.nav-group-mobile[open] .arr { transform: rotate(180deg); }
.nav-group-mobile > div { display: flex; flex-direction: column; padding-left: 6px; }
.nav-group-mobile > div a { padding: 9px 12px 9px 24px; border-radius: 8px; color: var(--ink-soft); font-size: 14px; }
.nav-group-mobile > div a:hover { color: var(--ink); background: var(--paper-2); }
.nav-group-mobile > div a.active { color: var(--accent-deep); font-weight: 600; background: var(--accent-soft); }

.nav-actions { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }

.btn {
  position: relative; display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 11px 22px; border-radius: 999px;
  font-size: 14px; font-weight: 600; cursor: pointer; white-space: nowrap;
  border: 1px solid transparent; font-family: inherit; line-height: 1;
  overflow: hidden;
  transition: transform .25s var(--ease), box-shadow .3s var(--ease), background .25s, border-color .25s, color .25s;
}
.btn::after {
  content: ""; position: absolute; top: 0; left: -80%; width: 45%; height: 100%;
  background: linear-gradient(105deg, transparent, rgba(255,255,255,.5), transparent);
  transform: skewX(-20deg); transition: left .65s var(--ease); pointer-events: none;
}
.btn:hover::after { left: 135%; }
.btn:active { transform: scale(.96); }
.btn-sm { padding: 9px 17px; font-size: 13px; }
.btn-primary { background: var(--ink); color: var(--paper); box-shadow: 0 8px 22px rgba(0,0,0,0.16); }
.btn-primary:hover { background: #000; transform: translateY(-2px); box-shadow: 0 14px 34px rgba(0,0,0,0.26); }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--line-strong); }
.btn-ghost:hover { border-color: var(--ink); background: var(--paper-2); transform: translateY(-2px); }

.nav-burger { display: none; flex-direction: column; gap: 5px; background: none; border: 1px solid var(--line-strong); border-radius: 8px; padding: 8px 9px; cursor: pointer; transition: border-color .2s, background .2s; }
.nav-burger:hover { border-color: var(--ink); background: var(--paper-2); }
.nav-burger span { width: 18px; height: 2px; background: var(--ink); border-radius: 2px; transition: transform .3s var(--ease), opacity .3s; }
.nav-burger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-burger.open span:nth-child(2) { opacity: 0; }
.nav-burger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.mobile-menu { display: none; flex-direction: column; gap: 2px; padding: 12px 20px 18px; border-bottom: 1px solid var(--line); background: var(--paper); }
.mobile-menu.open { display: flex; }
.mobile-menu a { padding: 11px 12px; border-radius: 8px; color: var(--ink-soft); font-size: 14.5px; transition: background .2s, color .2s, padding-left .25s var(--ease); }
.mobile-menu a:hover { background: var(--paper-2); color: var(--ink); padding-left: 18px; }
.mobile-menu .btn { margin-top: 8px; }


.page { padding-top: 132px; padding-bottom: 90px; position: relative; flex: 1 0 auto; width: 100%; }


.page-head { padding-bottom: 44px; margin-bottom: 10px; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 12px;
  font-size: 12px; letter-spacing: 3px; text-transform: uppercase;
  color: var(--accent); font-weight: 600;
  opacity: 0; transform: translateY(12px);
  transition: opacity .8s var(--ease), transform .8s var(--ease);
}
.eyebrow::before { content: ""; width: 0; height: 1px; background: var(--accent); transition: width .9s var(--ease) .15s; }
body.ready .eyebrow { opacity: 1; transform: none; }
body.ready .eyebrow::before { width: 26px; }

.h1 {
  margin: 22px 0 16px;
  font-family: var(--serif); font-weight: 500;
  font-size: clamp(34px, 5vw, 50px); line-height: 1.18; letter-spacing: -0.5px;
}
.h1 em { font-style: italic; color: var(--accent); }
.h1 .line { display: block; overflow: hidden; padding-bottom: .08em; margin-bottom: -.08em; }
.h1 .w { display: inline-block; transform: translateY(118%); transition: transform 1s var(--ease); }
body.ready .h1 .w { transform: translateY(0); }
body.ready .h1 .line:nth-child(1) .w:nth-child(1) { transition-delay: .25s; }
body.ready .h1 .line:nth-child(1) .w:nth-child(2) { transition-delay: .32s; }
body.ready .h1 .line:nth-child(1) .w:nth-child(3) { transition-delay: .39s; }
body.ready .h1 .line:nth-child(2) .w:nth-child(1) { transition-delay: .5s; }
body.ready .h1 .line:nth-child(2) .w:nth-child(2) { transition-delay: .57s; }
body.ready .h1 .line:nth-child(2) .w:nth-child(3) { transition-delay: .64s; }
body.ready .h1 .line:nth-child(2) .w:nth-child(4) { transition-delay: .71s; }

.lead {
  max-width: 620px; color: var(--ink-soft); font-size: 16px; line-height: 1.85;
  opacity: 0; transform: translateY(18px);
  transition: opacity .9s var(--ease), transform .9s var(--ease);
}
body.ready .lead { opacity: 1; transform: none; transition-delay: .72s; }


.sec { padding: 42px 0 8px; scroll-margin-top: 96px; }
.sec-head { display: flex; align-items: baseline; gap: 18px; margin-bottom: 24px; }
.sec-no { font-family: var(--serif); font-style: italic; color: var(--accent); font-size: 15px; }
.sec-title { font-family: var(--serif); font-weight: 600; font-size: 25px; letter-spacing: -0.3px; }
.sec-sub { color: var(--muted); font-size: 13.5px; margin-left: auto; white-space: nowrap; }
.rule { position: relative; height: 1px; background: var(--line); margin-bottom: 6px; overflow: hidden; }
.rule::after { content: ""; position: absolute; left: 0; top: 0; height: 100%; width: 100%; background: var(--accent); transform: scaleX(0); transform-origin: 0 50%; }
.rule.draw::after { transform: scaleX(1); transition: transform 1.1s var(--ease); }


.card {
  border-radius: 14px; padding: 24px 26px;
  background: var(--paper-2);
  border: 1px solid var(--line-strong);
  box-shadow: var(--shadow-sm);
  transition: box-shadow .4s var(--ease), border-color .4s, transform .4s var(--ease);
  position: relative;
}
.card:hover { box-shadow: var(--shadow-md); border-color: var(--line-strong); }
.card h3.card-title { font-family: var(--serif); font-weight: 600; font-size: 18px; margin-bottom: 14px; display: flex; align-items: center; gap: 10px; }
.card h3.card-title .n { font-style: italic; color: var(--faint); font-size: 14px; }


.alert { border-radius: 12px; padding: 14px 18px; font-size: 14px; line-height: 1.7; border: 1px solid; display: flex; gap: 12px; align-items: flex-start; }
.alert .a-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; margin-top: 8px; animation: dotPulse 2.4s ease-in-out infinite; }
.alert.dark { background: rgba(0,0,0,0.05); border-color: rgba(0,0,0,0.3); color: var(--ink); }
.alert.dark .a-dot { background: var(--ink); }
.alert.soft { background: var(--paper-2); border-color: var(--line); color: var(--ink-soft); }
.alert.soft .a-dot { background: var(--muted); }
.alert strong { display: block; }
.alert .alert-body { min-width: 0; }
.alert code, .inline-code {
  font-family: var(--mono); font-size: 0.9em;
  background: rgba(0, 0, 0, 0.07); padding: 1px 6px; border-radius: 5px; color: var(--ink);
}
@keyframes dotPulse { 0%, 100% { box-shadow: 0 0 0 3px rgba(0,0,0,.12); } 50% { box-shadow: 0 0 0 7px rgba(0,0,0,.04); } }


.codeblock {
  position: relative; border-radius: 14px; overflow: hidden;
  border: 1px solid var(--line-strong);
  background: #f4f4f4;
  box-shadow: var(--shadow-sm);
  transition: box-shadow .4s var(--ease), transform .4s var(--ease);
}
  .codeblock:hover { box-shadow: var(--shadow-md); }
.codeblock::before { content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 3px; background: linear-gradient(180deg, var(--accent), var(--accent-soft)); transform: scaleY(0); transform-origin: 0 0; transition: transform .5s var(--ease); }
.codeblock:hover::before { transform: scaleY(1); }
.cb-bar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 9px 16px; border-bottom: 1px solid var(--line); background: var(--paper-2);
  transform: translateY(-100%);
}
.codeblock.in .cb-bar { transform: translateY(0); transition: transform .7s var(--ease) .1s; }
.cb-bar .cb-name { font-family: var(--mono); font-size: 11.5px; color: var(--muted); letter-spacing: 0.4px; display: inline-flex; align-items: center; gap: 9px; }
.cb-bar .cb-name .lang { width: 20px; height: 20px; border-radius: 5px; display: grid; place-items: center; background: var(--ink); color: var(--paper); font-size: 9px; font-weight: 700; }
.cb-bar .cb-copy { border: 1px solid var(--line-strong); background: transparent; color: var(--muted); border-radius: 8px; padding: 4px 13px; font-size: 12px; cursor: pointer; font-family: inherit; transition: all .25s; }
.cb-bar .cb-copy:hover { color: var(--accent-deep); border-color: var(--accent); background: var(--accent-soft); }
.codeblock pre { position: relative; margin: 0; padding: 18px 20px; overflow-x: auto; font-family: var(--mono); font-size: 13px; line-height: 1.85; color: #222222; white-space: pre; opacity: 0; }
.codeblock.in pre { opacity: 1; transition: opacity .8s ease .25s; }
.codeblock pre::after { content: ""; position: absolute; left: 0; right: 0; top: var(--scan-y, -20px); height: 2px; background: linear-gradient(90deg, transparent, rgba(0,0,0,0.35), transparent); opacity: 0; pointer-events: none; transition: opacity .3s; }
.codeblock:hover pre::after { opacity: 1; }
.codeblock pre .ln { display: inline-block; width: 2ch; margin-right: 1.2em; text-align: right; color: #c4c4c4; user-select: none; font-size: 11.5px; }
.codeblock .tk-k { color: #111111; font-weight: 600; }
.codeblock .tk-f { color: #000000; }
.codeblock .tk-s { color: #333333; }
.codeblock .tk-c { color: #999999; }
.codeblock .tk-p { color: #444444; }


.table-wrap { overflow-x: auto; border-radius: 0 0 14px 14px; }
.elegant-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.elegant-table th { text-align: left; font-weight: 600; font-size: 12px; letter-spacing: 1.4px; text-transform: uppercase; color: var(--faint); padding: 12px 16px; border-bottom: 1px solid var(--line-strong); }
  .elegant-table td { padding: 14px 16px; border-bottom: 1px solid var(--line); color: var(--ink); vertical-align: middle; transition: background .25s; }
.elegant-table tbody tr { transition: background .2s; }
  .elegant-table tbody tr:hover td { background: var(--paper-2); }
.elegant-table td.key { color: var(--ink-soft); font-weight: 600; white-space: nowrap; width: 140px; }
.elegant-table td.num { text-align: right; font-weight: 700; font-family: var(--mono); white-space: nowrap; }
.elegant-table .foot-note, .foot-note { padding: 14px 18px; font-size: 12.5px; color: var(--ink-soft); background: var(--paper-3); border-top: 1px solid var(--line); font-family: var(--serif); font-style: italic; letter-spacing: .2px; }
  .cta-row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; margin-top: 18px; }


.tag { display: inline-block; padding: 3px 11px; border-radius: 999px; font-size: 12px; font-weight: 600; letter-spacing: 0.3px; border: 1px solid var(--line-strong); background: var(--paper-2); color: var(--ink-soft); transition: transform .25s var(--ease), border-color .25s, box-shadow .25s; }
.tag:hover { transform: translateY(-2px); }
.tag.dark { border-color: var(--ink); background: var(--ink); color: var(--paper); }
.tag.gray { border-color: var(--line); background: transparent; color: var(--muted); }
.tag.ok { border-color: var(--ink); background: transparent; color: var(--ink); }
.tag.warn { border-color: var(--line-strong); background: var(--paper-2); color: var(--ink-soft); }


.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 14px; }
.stat { padding: 20px 22px; }
.stat .l { font-size: 11px; letter-spacing: 2px; text-transform: uppercase; color: var(--faint); font-weight: 600; display: inline-flex; align-items: center; gap: 8px; }
.stat .l::before { content: ""; width: 6px; height: 6px; border-radius: 1.5px; background: var(--accent); opacity: .5; transform: rotate(45deg); }
.stat .v { font-family: var(--mono); font-size: 26px; font-weight: 700; margin-top: 8px; letter-spacing: -0.5px; }
.stat .s { font-size: 12px; color: var(--muted); margin-top: 5px; }


.step { display: flex; gap: 18px; margin: 30px 0 6px; }
.step .step-no {
  flex-shrink: 0; width: 42px; height: 42px; border-radius: 50%;
  display: grid; place-items: center;
  font-family: var(--serif); font-style: italic; font-size: 16px;
  border: 1px solid var(--ink); color: var(--ink);
  transition: background .3s, color .3s;
}
.step:hover .step-no { background: var(--ink); color: var(--paper); }
.step .step-body { min-width: 0; }
.step .step-body h4 { font-family: var(--serif); font-weight: 600; font-size: 20px; margin-bottom: 8px; }
.step .step-body p, .step .step-body li { color: var(--ink-soft); font-size: 14.5px; }
.step .step-body ul, .step .step-body ol { padding-left: 20px; margin: 6px 0; }
.step .step-body li { margin-bottom: 4px; }


.checklist { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 12px; }
.checklist .check { display: flex; gap: 12px; align-items: flex-start; padding: 14px 16px; border: 1px solid var(--line); border-radius: 12px; background: var(--paper-2); transition: transform .25s var(--ease), border-color .25s, box-shadow .3s var(--ease); }
.checklist .check:hover { transform: translateY(-3px); border-color: var(--ink); box-shadow: var(--shadow-sm); }
.checklist .check .tick { width: 22px; height: 22px; border-radius: 50%; background: var(--ink); color: var(--paper); display: grid; place-items: center; flex-shrink: 0; margin-top: 2px; }
.checklist .check .tick svg { width: 11px; height: 11px; }
.checklist .check span { font-size: 14px; color: var(--ink-soft); line-height: 1.6; }


.flow { display: flex; align-items: stretch; justify-content: center; gap: 8px; flex-wrap: wrap; padding: 14px 0; }
.flow .node {
  min-width: 118px; padding: 14px 14px; text-align: center;
  border: 1.5px solid var(--line-strong); border-radius: 12px; background: var(--paper-2);
  transition: transform .3s var(--ease), border-color .3s, box-shadow .3s var(--ease);
}
.flow .node:hover { transform: translateY(-4px); border-color: var(--ink); box-shadow: var(--shadow-sm); }
.flow .node b { display: block; font-size: 14px; font-weight: 700; }
.flow .node small { display: block; margin-top: 4px; font-size: 11px; color: var(--muted); letter-spacing: 0.5px; }
.flow .arrow { align-self: center; color: var(--faint); font-size: 20px; font-family: var(--serif); }


details.card summary { cursor: pointer; list-style: none; display: flex; align-items: center; justify-content: space-between; font-family: var(--serif); font-weight: 600; font-size: 17px; }
details.card summary::-webkit-details-marker { display: none; }
details.card summary .arr { font-family: var(--sans); font-size: 13px; color: var(--muted); transition: transform .3s var(--ease); }
details.card[open] summary .arr { transform: rotate(180deg); }
details.card .details-body { margin-top: 16px; }
details.card .details-body p { color: var(--ink-soft); font-size: 14.5px; margin: 6px 0; }
details.card .details-body h5 { font-family: var(--serif); font-weight: 600; font-size: 15px; margin: 18px 0 8px; color: var(--ink); }


  .field { display: flex; gap: 10px; flex-wrap: wrap; }
  .field .btn { flex-shrink: 0; }
  input + .btn, .btn + input { margin-left: 10px; }
.field input, .field select, .field textarea {
  flex: 1; min-width: 260px;
  padding: 12px 16px; border-radius: 11px;
  border: 1px solid var(--line-strong); background: var(--paper);
  color: var(--ink); font-size: 14px; font-family: var(--mono);
  outline: none; transition: border-color .25s, box-shadow .25s;
}
.field input:focus { border-color: var(--ink); box-shadow: 0 0 0 3px rgba(0,0,0,0.08); }
.field input::placeholder { color: var(--faint); font-family: var(--sans); }


.to-top {
  position: fixed; right: 26px; bottom: 30px; z-index: 80;
  width: 46px; height: 46px; border-radius: 50%;
  display: grid; place-items: center;
  background: var(--ink); color: var(--paper);
  border: none; cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0; transform: translateY(16px) scale(.9);
  pointer-events: none;
  transition: opacity .4s var(--ease), transform .4s var(--ease-spring), background .25s;
}
.to-top.show { opacity: 1; transform: none; pointer-events: auto; }
.to-top:hover { background: var(--accent-deep); }
.to-top svg { width: 18px; height: 18px; transition: transform .3s var(--ease); }
.to-top:hover svg { transform: translateY(-2px); }


.toast {
  position: fixed; top: 84px; left: 50%; z-index: 200;
  transform: translate(-50%, -16px);
  display: inline-flex; align-items: center; gap: 10px;
  padding: 11px 20px 11px 16px; border-radius: 999px;
  font-size: 13.5px; font-weight: 600; color: var(--ink);
  background: rgba(255, 255, 255, 0.95);
  border: 1px solid var(--line-strong);
  box-shadow: var(--shadow-md);
  opacity: 0; pointer-events: none;
  transition: opacity .4s var(--ease), transform .5s var(--ease-spring);
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.toast .tick { width: 20px; height: 20px; border-radius: 50%; display: grid; place-items: center; background: var(--ink); color: var(--paper); flex-shrink: 0; }
.toast .tick svg { width: 11px; height: 11px; }


.footer {
  background: var(--ink); color: var(--paper);
  padding: 64px 0 40px; margin-top: 70px; position: relative; z-index: 1; overflow: hidden;
  flex-shrink: 0;
}
.footer::before { content: ""; position: absolute; top: 0; left: 0; right: 0; height: 2px; background: linear-gradient(90deg, transparent, var(--accent), transparent); }
.footer   .foot-mark {
  position: absolute; right: -20px; bottom: -60px;
  font-family: var(--serif); font-style: italic; font-weight: 700;
  font-size: clamp(120px, 22vw, 300px); line-height: 1;
  color: rgba(255, 255, 255, 0.04); pointer-events: none; user-select: none;
  transform: none;
  transition: opacity .8s var(--ease);
}
  body.ready .footer .foot-mark { opacity: 1; }
.foot-in { max-width: 1160px; margin: 0 auto; padding: 0 26px; display: flex; flex-direction: column; gap: 36px; position: relative; z-index: 1; }
.foot-top { display: flex; align-items: flex-start; justify-content: space-between; flex-wrap: wrap; gap: 28px; }
.foot-brand .logo-text strong { color: var(--paper); }
.foot-brand .logo-text em { color: rgba(255, 255, 255, 0.55); }
  .foot-brand .logo-badge { background: #ffffff; color: #4361ee; }
  .foot-brand .logo-badge:hover { transform: rotate(-10deg) scale(1.06); }
.foot-tagline { margin-top: 14px; color: rgba(255, 255, 255, 0.62); font-size: 14px; max-width: 340px; line-height: 1.8; }
.foot-links { display: flex; gap: 56px; flex-wrap: wrap; }
.foot-col h4 { font-family: var(--serif); font-weight: 600; font-size: 14px; letter-spacing: 1.6px; text-transform: uppercase; color: var(--paper); margin-bottom: 14px; display: inline-flex; align-items: center; gap: 8px; }
.foot-col h4::before { content: ""; width: 12px; height: 1px; background: var(--accent); }
.foot-col ul { list-style: none; }
.foot-col ul li { margin-bottom: 9px; }
  .foot-col ul a { position: relative; color: rgba(255, 255, 255, 0.58); font-size: 13.5px; transition: color .25s, transform .3s var(--ease); }
.foot-col ul a::before { content: ""; position: absolute; left: 0; top: 50%; width: 0; height: 1px; background: var(--accent); transform: translateY(-50%); transition: width .3s var(--ease); }
  .foot-col ul a:hover { color: var(--paper); transform: translateX(6px); }
.foot-col ul a:hover::before { width: 8px; }
.foot-bottom { padding-top: 24px; border-top: 1px solid rgba(255, 255, 255, 0.14); display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 12px; color: rgba(255, 255, 255, 0.45); font-size: 12.5px; }
.foot-bottom a { color: var(--accent-soft); position: relative; transition: color .2s; }
.foot-bottom a::after { content: ""; position: absolute; left: 0; right: 0; bottom: -1px; height: 1px; background: rgba(255, 255, 255, 0.5); transform: scaleX(0); transform-origin: 0 50%; transition: transform .3s var(--ease); }
.foot-bottom a:hover { color: #fff; }
.foot-bottom a:hover::after { transform: scaleX(1); }


.reveal { opacity: 0; transform: translateY(30px); transition: opacity .9s var(--ease), transform .9s var(--ease); }
.reveal.visible { opacity: 1; transform: none; }

/* 版本切换按钮（标准版 / 复杂版互切） */
.version-switch{display:inline-flex;align-items:center;gap:6px;padding:8px 14px;border-radius:999px;font-size:12.5px;font-weight:600;color:var(--ink-soft);border:1px solid var(--line-strong);background:var(--paper);transition:.2s;white-space:nowrap;text-decoration:none;cursor:pointer}
.version-switch:hover{color:var(--ink);border-color:var(--ink);background:var(--paper-2);text-decoration:none}
.version-switch svg{width:14px;height:14px;flex-shrink:0}
.reveal-l { opacity: 0; transform: translateX(-36px); transition: opacity .9s var(--ease), transform .9s var(--ease); }
.reveal-l.visible { opacity: 1; transform: none; }
.reveal-zoom { opacity: 0; transform: scale(.94); transition: opacity .9s var(--ease), transform .9s var(--ease); }
.reveal-zoom.visible { opacity: 1; transform: none; }
.reveal-blur { opacity: 0; transform: translateY(20px); filter: blur(10px); transition: opacity 1s var(--ease), transform 1s var(--ease), filter 1s var(--ease); }
.reveal-blur.visible { opacity: 1; transform: none; filter: none; }

.stagger > * { opacity: 0; transform: translateY(26px); transition: opacity .8s var(--ease), transform .8s var(--ease); }
.stagger.in > * { opacity: 1; transform: none; }
.stagger.in > *:nth-child(1) { transition-delay: .08s; }
.stagger.in > *:nth-child(2) { transition-delay: .16s; }
.stagger.in > *:nth-child(3) { transition-delay: .24s; }
.stagger.in > *:nth-child(4) { transition-delay: .32s; }
.stagger.in > *:nth-child(5) { transition-delay: .40s; }
.stagger.in > *:nth-child(6) { transition-delay: .48s; }
.stagger.in > *:nth-child(7) { transition-delay: .56s; }
.stagger.in > *:nth-child(8) { transition-delay: .64s; }


@media (max-width: 980px) {
  .nav-links, .nav-actions .btn-ghost { display: none; }
  .nav-burger { display: flex; }
  .sec-head { flex-wrap: wrap; gap: 10px; }
  .sec-sub { margin-left: 0; white-space: normal; width: 100%; }
}

@media (max-width: 520px) {
  .page { padding-top: 112px; }
  .h1 { font-size: 32px; }
  .to-top { right: 16px; bottom: 20px; }
  .card { padding: 20px 18px; }
}



.nav-account { position: relative; }
.nav-account summary { list-style: none; cursor: pointer; padding: 8px 13px; border-radius: 9px; font-size: 13.5px; color: var(--ink-soft); display: flex; align-items: center; gap: 6px; white-space: nowrap; transition: color .2s, background .2s; }
.nav-account summary::-webkit-details-marker { display: none; }
.nav-account summary:hover { color: var(--ink); background: var(--paper-2); }
.nav-account[open] summary { color: var(--accent-deep); font-weight: 600; background: var(--accent-soft); }
.nav-account .arr { font-size: 10px; transition: transform .25s var(--ease); }
.nav-account[open] .arr { transform: rotate(180deg); }
.nav-account-body { position: absolute; top: calc(100% + 8px); right: 0; min-width: 176px; padding: 6px; display: flex; flex-direction: column; gap: 2px; background: var(--paper); border: 1px solid var(--line-strong); border-radius: 10px; box-shadow: var(--shadow-md); z-index: 100; }
.nav-account-body a, .nav-account-body button { padding: 8px 12px; border-radius: 7px; font-size: 13.5px; color: var(--ink-soft); white-space: nowrap; text-align: left; background: none; border: none; width: 100%; cursor: pointer; font-family: inherit; }
.nav-account-body a:hover, .nav-account-body button:hover { color: var(--ink); background: var(--paper-2); }
.nav-account-mobile summary { list-style: none; cursor: pointer; padding: 11px 12px; border-radius: 9px; color: var(--ink-soft); font-size: 14.5px; display: flex; align-items: center; justify-content: space-between; transition: color .2s, background .2s; }
.nav-account-mobile summary::-webkit-details-marker { display: none; }
.nav-account-mobile summary:hover { color: var(--ink); background: var(--paper-2); }
.nav-account-mobile .arr { font-size: 10px; transition: transform .25s; }
.nav-account-mobile[open] .arr { transform: rotate(180deg); }
.nav-account-mobile > div { display: flex; flex-direction: column; padding-left: 6px; }
.nav-account-mobile a, .nav-account-mobile button { padding: 9px 12px 9px 24px; border-radius: 8px; color: var(--ink-soft); font-size: 14px; text-align: left; background: none; border: none; font-family: inherit; cursor: pointer; }
.nav-account-mobile a:hover, .nav-account-mobile button:hover { color: var(--ink); background: var(--paper-2); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001s !important;
    animation-delay: 0s !important;
    transition-duration: 0.001s !important;
  }
  .grain { animation: none; }
  .reveal, .reveal-l, .reveal-zoom, .reveal-blur, .stagger > * { opacity: 1; transform: none; filter: none; }
  .preloader { display: none; }
}