/* Lamplit — site and docs. Black, white and gray like the app, with one violet
   (紫气东来) for the headline, the main button and the glow: plain black and white
   reads as mourning to a Chinese eye. */
:root {
  --bg: #0A0A0A;
  --bg-2: #101010;
  --surface: #141414;
  --surface-2: #1C1C1C;
  --text: #EDEDED;
  --muted: #A3A3A3;
  --dim: #737373;
  --line: rgba(255, 255, 255, .08);
  --line-2: rgba(255, 255, 255, .14);
  --accent: #8B7CF6;
  --accent-2: #A194F8;
  --accent-ink: #0A0A0A;
  --accent-soft: rgba(139, 124, 246, .14);
  --glow: rgba(139, 124, 246, .20);
  --shadow: 0 30px 80px rgba(0, 0, 0, .55), 0 2px 6px rgba(0, 0, 0, .4);
  --serif: "Noto Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", "Noto Sans SC", sans-serif;
  --mono: ui-monospace, "Cascadia Code", Consolas, monospace;
  color-scheme: dark;
}
@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #FFFFFF; --bg-2: #F5F5F5; --surface: #FFFFFF; --surface-2: #F2F2F2;
    --text: #0A0A0A; --muted: #525252; --dim: #8A8A8A;
    --line: rgba(0, 0, 0, .08); --line-2: rgba(0, 0, 0, .14);
    --accent: #6A5AE0; --accent-2: #5A49D6; --accent-ink: #FFFFFF;
    --accent-soft: rgba(106, 90, 224, .08); --glow: rgba(139, 124, 246, .22);
    --shadow: 0 30px 70px rgba(0, 0, 0, .12), 0 2px 6px rgba(0, 0, 0, .06);
    color-scheme: light;
  }
}
:root[data-theme="light"] {
  --bg: #FFFFFF; --bg-2: #F5F5F5; --surface: #FFFFFF; --surface-2: #F2F2F2;
  --text: #0A0A0A; --muted: #525252; --dim: #8A8A8A;
  --line: rgba(0, 0, 0, .08); --line-2: rgba(0, 0, 0, .14);
  --accent: #6A5AE0; --accent-2: #5A49D6; --accent-ink: #FFFFFF;
  --accent-soft: rgba(106, 90, 224, .08); --glow: rgba(139, 124, 246, .22);
  --shadow: 0 30px 70px rgba(0, 0, 0, .12), 0 2px 6px rgba(0, 0, 0, .06);
  color-scheme: light;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 16px/1.75 var(--sans); letter-spacing: .01em;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; }
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 24px; }
.narrow { max-width: 760px; }
h1, h2, h3, h4, blockquote { font-family: var(--serif); font-weight: 600; letter-spacing: .02em; text-wrap: balance; }
.lead, .sub, .faq details p { text-wrap: pretty; }
code { font-family: var(--mono); font-size: .88em; background: var(--accent-soft); color: var(--text); padding: 1px 6px; border-radius: 5px; }
::selection { background: var(--accent); color: var(--accent-ink); }

/* top bar */
.top { position: sticky; top: 0; z-index: 20; background: color-mix(in srgb, var(--bg) 78%, transparent); backdrop-filter: saturate(140%) blur(14px); -webkit-backdrop-filter: saturate(140%) blur(14px); border-bottom: 1px solid var(--line); }
.bar { display: flex; align-items: center; height: 64px; gap: 16px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-family: var(--serif); font-weight: 600; font-size: 18px; }
.brand img { border-radius: 7px; }
.brand .en { font-family: var(--sans); font-weight: 500; font-size: 13px; color: var(--dim); letter-spacing: .08em; }
.top nav { margin-left: auto; display: flex; align-items: center; gap: 26px; font-size: 14.5px; }
.top nav a { color: var(--muted); transition: color .2s; }
.top nav a:hover { color: var(--text); }
.theme { width: 30px; height: 30px; border-radius: 50%; border: 1px solid var(--line-2); background: transparent; cursor: pointer; display: grid; place-items: center; padding: 0; }
.theme span { width: 12px; height: 12px; border-radius: 50%; background: linear-gradient(90deg, var(--text) 50%, transparent 50%); border: 1.5px solid var(--text); }
@media (max-width: 760px) { .hide-sm { display: none; } .top nav { gap: 18px; } }
@media (max-width: 420px) { .hide-xs { display: none; } .brand .en { display: none; } }

/* buttons */
.btn { display: inline-flex; align-items: center; gap: 9px; height: 46px; padding: 0 22px; border-radius: 999px; font-weight: 500; font-size: 15px; border: 1px solid var(--line-2); color: var(--text); transition: border-color .2s, background .2s, transform .2s; white-space: nowrap; }
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); box-shadow: 0 10px 34px var(--glow); }
.btn.primary:hover { background: var(--accent-2); border-color: var(--accent-2); transform: translateY(-1px); }
.btn.ghost { border-color: transparent; color: var(--muted); padding: 0 10px; }
.btn.ghost:hover { color: var(--text); }

/* hero */
.hero { position: relative; overflow: hidden; padding: 112px 0 40px; text-align: center; }
.glow { position: absolute; left: 50%; top: -120px; width: 900px; height: 700px; transform: translateX(-50%); background: radial-gradient(closest-side, var(--glow), transparent 70%); pointer-events: none; }
.kicker { position: relative; margin: 0 0 22px; font-size: 13px; letter-spacing: .32em; color: var(--accent); text-transform: uppercase; }
.hero h1 { position: relative; margin: 0 0 26px; font-size: clamp(40px, 7.4vw, 82px); line-height: 1.12; font-weight: 600; letter-spacing: .03em; }
.hero h1 em { font-style: normal; color: var(--accent); }
.br-sm { display: none; }
@media (max-width: 560px) { .br-sm { display: inline; } }
.lead { position: relative; max-width: 640px; margin: 0 auto 38px; font-size: clamp(16px, 2vw, 18.5px); color: var(--muted); line-height: 1.85; }
.cta { position: relative; display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; }
.meta { position: relative; margin: 20px 0 0; font-size: 13px; color: var(--dim); }
.meta i { display: inline-block; width: 3px; height: 3px; border-radius: 50%; background: var(--dim); margin: 0 12px; vertical-align: middle; }

/* product mock */
.stage { position: relative; margin: 76px auto 0; max-width: 1000px; }
.stage::before { content: ""; position: absolute; inset: 12% 6% -6%; background: radial-gradient(closest-side, var(--glow), transparent); filter: blur(30px); z-index: 0; }
.win { position: relative; z-index: 1; text-align: left; border-radius: 16px; overflow: hidden; background: var(--surface); border: 1px solid var(--line-2); box-shadow: var(--shadow); }
.win-bar { display: flex; align-items: center; gap: 7px; height: 40px; padding: 0 16px; border-bottom: 1px solid var(--line); background: var(--bg-2); }
.win-bar span { width: 10px; height: 10px; border-radius: 50%; background: var(--line-2); }
.win-bar b { margin: 0 auto; font-weight: 500; font-size: 12.5px; color: var(--dim); padding-right: 50px; }
.win-body { display: grid; grid-template-columns: 230px 1fr; min-height: 430px; }
.win-side { border-right: 1px solid var(--line); padding: 14px 10px; background: var(--bg-2); }
.who { display: flex; align-items: center; gap: 11px; padding: 10px; border-radius: 10px; }
.who.on { background: var(--surface-2); }
.who b { display: block; font-size: 14px; font-weight: 500; }
.who small { display: block; font-size: 12px; color: var(--dim); line-height: 1.4; }
.av { width: 30px; height: 30px; border-radius: 50%; flex: none; }
.a1 { background: linear-gradient(160deg, #9a8ef5, #7c6cf0); }
.a2 { background: linear-gradient(160deg, #e48a6d, #e0744f); }
.a3 { background: linear-gradient(160deg, #5cb3e8, #3d9be0); }
.a4 { background: linear-gradient(160deg, #4cc0b2, #2bab9c); }
.win-chat { padding: 26px 30px; display: flex; flex-direction: column; gap: 14px; }
.msg { max-width: 76%; padding: 11px 15px; border-radius: 14px; font-size: 14.5px; line-height: 1.6; }
.msg.me { align-self: flex-end; background: var(--accent-soft); border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent); }
.msg.bot { align-self: flex-start; background: var(--surface-2); }
.card { max-width: 82%; border: 1px solid var(--line-2); border-radius: 14px; padding: 14px 18px; background: var(--bg-2); font-size: 14px; }
.card-h { display: flex; align-items: center; gap: 9px; font-weight: 500; margin-bottom: 8px; }
.dot { width: 7px; height: 7px; border-radius: 50%; background: var(--dim); }
.dot.warm { background: var(--accent); box-shadow: 0 0 10px var(--accent); }
.task ol { list-style: none; margin: 0; padding: 0; }
.task li { position: relative; padding: 3px 0 3px 26px; color: var(--muted); }
.task li::before { content: ""; position: absolute; left: 2px; top: 10px; width: 12px; height: 12px; border-radius: 50%; border: 1.5px solid var(--line-2); }
.task li.done { color: var(--text); }
.task li.done::before { background: var(--accent); border-color: var(--accent); }
.task li.now::before { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.task li em { font-style: normal; color: var(--dim); margin-left: 6px; font-size: 13px; }
.ask p { margin: 0 0 12px; color: var(--muted); }
.ask-b { display: flex; gap: 8px; }
.b { font-size: 13px; padding: 5px 16px; border-radius: 999px; border: 1px solid var(--line-2); }
.b.ok { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.stage-note { margin: 18px 0 0; font-size: 12px; color: var(--dim); }
@media (max-width: 760px) {
  .win-body { grid-template-columns: 1fr; }
  .win-side { display: none; }
  .win-chat { padding: 20px 16px; }
  .msg, .card { max-width: 100%; }
  .hero { padding-top: 72px; }
  .stage { margin-top: 52px; }
}

/* sections */
section { padding: 120px 0; }
section h2 { margin: 0 0 14px; text-align: center; font-size: clamp(28px, 4vw, 42px); line-height: 1.3; }
.sub { margin: 0 auto 64px; max-width: 600px; text-align: center; color: var(--muted); }

.pillars { padding: 96px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.three { display: grid; grid-template-columns: repeat(3, 1fr); gap: 56px; }
.three .num { display: block; font-family: var(--serif); color: var(--accent); font-size: 14px; letter-spacing: .2em; margin-bottom: 18px; }
.three h3 { margin: 0 0 12px; font-size: 22px; }
.three p { margin: 0; color: var(--muted); font-size: 15px; }
@media (max-width: 860px) { .three { grid-template-columns: 1fr; gap: 44px; } }

.list { display: grid; grid-template-columns: 1fr 1fr; gap: 0 72px; margin: 0; }
.list div { padding: 28px 0; border-top: 1px solid var(--line); }
.list dt { font-family: var(--serif); font-weight: 600; font-size: 19px; margin-bottom: 8px; }
.list dd { margin: 0; color: var(--muted); font-size: 15px; }
@media (max-width: 760px) { .list { grid-template-columns: 1fr; } }

.safe { background: var(--bg-2); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.safe blockquote { margin: 0 auto 72px; max-width: 820px; text-align: center; font-size: clamp(26px, 3.6vw, 40px); line-height: 1.45; }
.four { display: grid; grid-template-columns: repeat(4, 1fr); gap: 40px; }
.four h4 { margin: 0 0 10px; font-size: 17px; color: var(--accent); }
.four p { margin: 0; color: var(--muted); font-size: 14.5px; }
@media (max-width: 900px) { .four { grid-template-columns: 1fr 1fr; } }
@media (max-width: 520px) { .four { grid-template-columns: 1fr; } }

.steps { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; counter-reset: s; }
.steps li { counter-increment: s; padding: 30px; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); }
.steps li::before { content: "0" counter(s); display: block; font-family: var(--serif); color: var(--accent); letter-spacing: .2em; font-size: 14px; margin-bottom: 18px; }
.steps h3 { margin: 0 0 10px; font-size: 20px; }
.steps p { margin: 0; color: var(--muted); font-size: 14.5px; }
@media (max-width: 860px) { .steps { grid-template-columns: 1fr; } }
.more { text-align: center; margin: 44px 0 0; }
.more a { color: var(--accent); border-bottom: 1px solid color-mix(in srgb, var(--accent) 40%, transparent); padding-bottom: 2px; }

.faq h2 { margin-bottom: 48px; }
.faq details { border-top: 1px solid var(--line); padding: 22px 0; }
.faq details:last-of-type { border-bottom: 1px solid var(--line); }
.faq summary { cursor: pointer; list-style: none; font-family: var(--serif); font-weight: 600; font-size: 18px; display: flex; justify-content: space-between; gap: 20px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--accent); font-family: var(--sans); font-weight: 400; font-size: 22px; line-height: 1; transition: transform .25s; }
.faq details[open] summary::after { transform: rotate(45deg); }
.faq details p { margin: 14px 0 0; color: var(--muted); font-size: 15px; }

footer { border-top: 1px solid var(--line); padding: 40px 0 56px; color: var(--dim); font-size: 14px; }
.foot { display: flex; flex-wrap: wrap; align-items: center; gap: 18px 36px; }
.foot .brand { font-size: 16px; color: var(--text); }
.foot nav { display: flex; flex-wrap: wrap; gap: 10px 26px; }
.foot nav a:hover { color: var(--text); }
.foot .was { margin-left: auto; }
@media (max-width: 640px) { .foot .was { margin-left: 0; } }

/* reveal on scroll */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity .8s ease, transform .8s ease; }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; transition: none; } html { scroll-behavior: auto; } }

/* ------------------------------------------------------------------ docs */
.docs { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 64px; padding: 64px 24px 120px; }
.toc { position: sticky; top: 96px; align-self: start; max-height: calc(100vh - 120px); overflow: auto; font-size: 14px; }
.toc p { margin: 0 0 12px; font-size: 12px; letter-spacing: .2em; color: var(--dim); }
.toc a { display: block; padding: 6px 0 6px 14px; color: var(--muted); border-left: 1px solid var(--line); }
.toc a:hover { color: var(--text); }
.toc a.on { color: var(--accent); border-left-color: var(--accent); }
.doc { max-width: 760px; }
.doc h1 { font-size: clamp(32px, 4.6vw, 46px); margin: 0 0 14px; }
.doc .intro { color: var(--muted); font-size: 17px; margin: 0 0 48px; }
.doc h2 { text-align: left; font-size: 26px; margin: 64px 0 16px; padding-top: 24px; border-top: 1px solid var(--line); scroll-margin-top: 90px; }
.doc h3 { font-size: 18px; margin: 32px 0 8px; }
.doc p, .doc li { color: var(--muted); font-size: 15.5px; }
.doc strong { color: var(--text); font-weight: 600; }
.doc ul, .doc ol { padding-left: 22px; }
.doc li { margin: 6px 0; }
.doc .tip { border-left: 2px solid var(--accent); background: var(--accent-soft); padding: 14px 18px; border-radius: 0 10px 10px 0; margin: 20px 0; }
.doc .tip p { margin: 0; color: var(--text); }
.doc table { width: 100%; border-collapse: collapse; margin: 18px 0; font-size: 14.5px; }
.doc th, .doc td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); vertical-align: top; }
.doc th { color: var(--text); font-weight: 600; }
.doc td { color: var(--muted); }
.doc .table { overflow-x: auto; }
@media (max-width: 860px) { .docs { grid-template-columns: 1fr; gap: 24px; padding-top: 40px; } .toc { position: static; max-height: none; display: none; } }