/* 随码 landing v0.2.1 — paper / ink / sage, two screens max on desktop. */

:root {
  color-scheme: light;
  --paper: #fafaf8;
  --ink: #242721;
  --muted: #646960;
  --line: #dddfd7;
  --sage: #e9eee6;
  --wash: #f0f2ed;
  --accent: #486751;
  --accent-deep: #3a5544;
  --serif: "Songti SC", "STSong", "Noto Serif CJK SC", Georgia, serif;
  --sans: "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  --ease: cubic-bezier(0.2, 0, 0, 1);
  --lift: 0 0 0 1px rgb(0 0 0 / .055), 0 3px 8px rgb(0 0 0 / .035), 0 24px 60px rgb(0 0 0 / .045);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-block-start: 24px; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 16px/1.7 var(--sans);
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; }
button, a, summary { -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible, summary:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 4px;
}
svg { fill: none; stroke: currentColor; stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; flex: none; }
p, h1, h2, h3 { margin: 0; }
p { color: var(--muted); }
h1, h2 { font-family: var(--serif); font-weight: 600; letter-spacing: -0.03em; text-wrap: balance; }
h3 { font-size: 18px; font-weight: 600; }
img { display: block; max-inline-size: 100%; block-size: auto; outline: 1px solid oklch(0 0 0 / .1); outline-offset: -1px; }
strong { color: var(--ink); font-weight: 600; }

.wrap { inline-size: min(1080px, calc(100% - 64px)); margin-inline: auto; }

.skip-link {
  position: absolute; inset-block-start: 10px; inset-inline-start: 16px;
  transform: translateY(-160%); background: #fff; padding: 10px 14px; z-index: 10;
  border-radius: 8px;
}
.skip-link:focus { transform: none; }

/* Header */
.site-header {
  display: flex; align-items: center; justify-content: space-between;
  gap: 20px; padding-block: 18px;
}
.wordmark {
  display: inline-flex; align-items: center; gap: 10px;
  font-size: 20px; font-weight: 600; min-block-size: 44px;
}
.wordmark svg { inline-size: 30px; block-size: 30px; stroke-width: 1.6; color: var(--accent); }
nav { display: flex; align-items: center; gap: 24px; font-size: 14px; }
nav a { display: inline-flex; align-items: center; min-block-size: 44px; }
nav a:hover { color: var(--accent); }
.nav-action {
  background: #fff; box-shadow: 0 0 0 1px rgb(0 0 0 / .09);
  padding-inline: 15px; border-radius: 8px; gap: 12px;
}

/* Hero */
.hero { text-align: center; padding-block: 20px 14px; }
.hero-note {
  display: flex; justify-content: center; align-items: center; gap: 8px;
  font-size: 13px; margin-block-end: 12px;
}
.status-dot { inline-size: 6px; block-size: 6px; border-radius: 50%; background: var(--accent); }
h1 { font-size: clamp(34px, 4.2vw, 52px); line-height: 1.16; }
.hero-lede {
  font-size: 16px; line-height: 1.85; margin: 10px auto 0;
  max-inline-size: 60ch; text-wrap: pretty;
}
.hero-actions { display: flex; justify-content: center; flex-wrap: wrap; gap: 12px; margin-block-start: 16px; }
.hero-meta {
  display: flex; justify-content: center; flex-wrap: wrap; gap: 10px;
  font-size: 12px; margin-block-start: 10px;
}
.hero-meta span[aria-hidden] { color: #b2b7ac; }

/* Buttons */
.button {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  min-block-size: 48px; padding: 11px 20px; border-radius: 10px;
  font-size: 14.5px; font-weight: 600; line-height: 1.4; text-align: center;
  transition: transform 150ms var(--ease), background-color 150ms var(--ease), box-shadow 150ms var(--ease);
}
.button svg { inline-size: 18px; block-size: 18px; stroke-width: 2; }
.button:active { transform: scale(0.96); }
.primary { color: #fff; background: var(--ink); box-shadow: 0 2px 3px rgb(0 0 0 / .08); }
.primary:hover { background: #3a443a; }
.secondary { background: #fff; box-shadow: 0 0 0 1px rgb(0 0 0 / .13); }
.secondary:hover { background: var(--sage); }

/* Demo */
.demo { padding-block: 0 40px; }
.demo-head { display: flex; justify-content: space-between; align-items: baseline; gap: 16px; margin-block-end: 8px; }
.demo-head h2 { font: 500 17px var(--sans); letter-spacing: 0; }
.demo-head p { font-size: 12.5px; }

.device-stage {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 40px 212px;
  align-items: center; gap: 18px;
  padding: 20px;
  background: var(--wash);
  border-radius: 20px;
}
.desktop-window { background: #fff; border-radius: 12px; box-shadow: var(--lift); overflow: hidden; }
.window-bar {
  display: flex; align-items: center; gap: 14px;
  padding: 11px 16px; border-block-end: 1px solid #edf0e9;
  font-size: 11.5px; color: var(--muted);
}
.window-dots { display: flex; gap: 5px; }
.window-dots i { inline-size: 7px; block-size: 7px; border-radius: 50%; background: #d7dbd1; }
.window-note { margin-inline-start: auto; font-size: 10.5px; }
.desktop-content {
  display: grid; grid-template-columns: minmax(0, 1fr) 132px;
  gap: 18px; padding: 18px; align-items: center;
}
.small-label { font-size: 10.5px; color: var(--muted); }
.demo-message p { font: 500 20px/1.7 var(--serif); color: var(--ink); margin-block: 10px 12px; }
.selection-tag {
  display: inline-block; font-size: 10.5px; color: var(--accent);
  background: var(--sage); padding: 3px 8px; border-radius: 4px;
}
.demo-qr { padding: 7px; border-radius: 8px; box-shadow: 0 0 0 1px rgb(0 0 0 / .07); text-align: center; }
.demo-qr img { outline: none; inline-size: 100%; block-size: auto; }
.demo-qr span { display: block; font-size: 9.5px; color: var(--muted); margin-block-start: 5px; }
.transfer-mark svg { inline-size: 34px; block-size: 34px; color: #8b9787; }

.phone-window { background: #fff; padding: 10px; border-radius: 24px; box-shadow: var(--lift); }
.phone-top { display: flex; justify-content: space-between; align-items: center; padding: 6px 5px; font-size: 12px; font-weight: 600; }
.phone-local { font-weight: 400; font-size: 8.5px; color: var(--muted); }
.phone-local i { display: inline-block; inline-size: 4px; block-size: 4px; background: var(--accent); border-radius: 50%; margin-inline-end: 3px; }
.phone-body {
  position: relative; display: grid; min-block-size: 196px; align-items: center;
  background: var(--paper); border-radius: 14px; margin-block: 7px 10px; padding: 16px 10px;
}
.demo-scan, .demo-received {
  grid-area: 1 / 1;
  transition: opacity 150ms var(--ease), transform 150ms var(--ease);
}
.demo-scan { text-align: center; }
.demo-scan svg { inline-size: 72px; block-size: 72px; color: var(--accent); margin-block-end: 8px; }
.demo-scan p { font: 16px var(--serif); color: var(--ink); }
.demo-received { opacity: 0; transform: translateY(4px); pointer-events: none; }
.demo-received p { font: 18px/1.8 var(--serif); color: var(--ink); margin-block-start: 10px; }
.phone-body[data-state="received"] .demo-scan,
.phone-body[data-state="copied"] .demo-scan { opacity: 0; transform: translateY(4px); pointer-events: none; }
.phone-body[data-state="received"] .demo-received,
.phone-body[data-state="copied"] .demo-received { opacity: 1; transform: none; }
.demo-button {
  display: flex; align-items: center; justify-content: center; gap: 8px;
  border: 0; inline-size: 100%; min-block-size: 42px; border-radius: 13px;
  background: var(--accent); color: #fff; font-size: 12.5px;
  transition: transform 150ms var(--ease), background-color 150ms var(--ease);
}
.demo-button:hover { background: var(--accent-deep); }
.demo-button:active { transform: scale(0.96); }
.icon-swap { position: relative; display: inline-flex; inline-size: 17px; block-size: 17px; }
.icon-swap svg {
  inline-size: 17px; block-size: 17px;
  transition: opacity 300ms var(--ease), scale 300ms var(--ease), filter 300ms var(--ease);
}
.icon-after { position: absolute; inset: 0; opacity: 0; scale: 0.25; filter: blur(4px); }
.demo-button[data-copied="true"] .icon-before { opacity: 0; scale: 0.25; filter: blur(4px); }
.demo-button[data-copied="true"] .icon-after { opacity: 1; scale: 1; filter: blur(0); }
.demo-caption { text-align: center; font-size: 12px; margin-block-start: 12px; min-block-size: 20px; }

/* Install (second screen) */
.install { padding-block: 10px 36px; }
.install-head { text-align: center; max-inline-size: 640px; margin-inline: auto; }
.section-kicker { font-size: 12.5px; color: var(--accent); margin-block-end: 8px; }
.install-head h2 { font-size: clamp(26px, 2.6vw, 34px); line-height: 1.35; }
.install-head > p:last-child { margin-block-start: 8px; font-size: 14.5px; }
.install-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 56px;
  margin-block: 28px 0; align-items: start;
}
.install-block { min-inline-size: 0; }
.install-block + .install-block { border-inline-start: 1px solid var(--line); padding-inline-start: 56px; }
.install-heading { display: flex; gap: 11px; align-items: center; margin-block-end: 12px; }
.install-heading svg { inline-size: 23px; block-size: 23px; }
.install-steps { padding-inline-start: 20px; margin-block: 0 16px; display: grid; gap: 9px; font-size: 14px; line-height: 1.7; }
.install-steps code { font-size: 12px; overflow-wrap: anywhere; background: #eef0ea; padding: 2px 5px; border-radius: 4px; }
.install-block .button { inline-size: 100%; }
.install-meta { display: block; font-size: 12px; color: var(--muted); margin-block-start: 9px; }
.mobile-install { display: flex; flex-wrap: wrap; align-items: center; gap: 18px; margin-block: 0 16px; }
.mobile-install > div { flex: 1 1 150px; min-inline-size: 0; overflow-wrap: anywhere; }
.mobile-install img { inline-size: 112px; flex: none; border-radius: 8px; }
.mobile-install p { font-size: 12.5px; line-height: 1.75; }
.mobile-install p + p { margin-block-start: 10px; }

.privacy-line {
  margin: 26px auto 0; max-inline-size: 760px; text-align: center;
  font-size: 13px; line-height: 1.8;
}

/* Collapsed FAQ, inside second screen */
.faq { max-inline-size: 860px; margin: 18px auto 0; border-block: 1px solid var(--line); }
.faq summary {
  cursor: pointer; list-style: none; display: flex; align-items: center; justify-content: space-between;
  gap: 16px; padding-block: 14px; font-size: 14px; min-block-size: 48px;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary span { font-size: 20px; line-height: 1; color: var(--muted); transition: transform 150ms var(--ease); }
.faq[open] summary span { transform: rotate(45deg); }
.faq-body { display: grid; grid-template-columns: 1fr 1fr; gap: 4px 36px; padding-block-end: 18px; }
.qa { min-inline-size: 0; padding-block: 8px; }
.qa h3 { font-size: 14px; margin-block-end: 4px; }
.qa p { font-size: 12.5px; line-height: 1.75; }

/* Footer */
.site-footer {
  border-block-start: 1px solid var(--line);
  display: flex; align-items: center; gap: 20px;
  padding-block: 18px 24px; font-size: 12px;
}
.site-footer .wordmark { font-size: 15px; }
.site-footer > a:last-child { margin-inline-start: auto; min-block-size: 44px; display: flex; align-items: center; gap: 8px; }

/* Responsive */
@media (max-width: 920px) {
  .device-stage { grid-template-columns: minmax(0, 1fr) 34px 190px; gap: 14px; padding: 18px; }
  .desktop-content { grid-template-columns: minmax(0, 1fr) 116px; gap: 14px; padding: 18px 16px; }
  .demo-message p { font-size: 18px; }
  .install-grid { gap: 36px; }
  .install-block + .install-block { padding-inline-start: 36px; }
}
@media (max-width: 760px) {
  .wrap { inline-size: calc(100% - 40px); }
  .site-header { padding-block: 14px; flex-wrap: wrap; gap: 10px; }
  nav { gap: 14px; }
  .hero { padding-block: 20px 18px; }
  h1 { font-size: clamp(30px, 8vw, 38px); }
  .hero-actions { flex-direction: column; align-items: stretch; }
  .hero-actions .button { inline-size: 100%; }
  .device-stage { grid-template-columns: 1fr; gap: 16px; padding: 16px; }
  .transfer-mark { display: none; }
  .desktop-window { max-inline-size: 420px; inline-size: 100%; justify-self: center; }
  .phone-window { max-inline-size: 250px; inline-size: 100%; justify-self: center; }
  .demo-head { align-items: flex-start; flex-direction: column; gap: 2px; }
  .install-grid { grid-template-columns: 1fr; gap: 30px; margin-block-start: 22px; }
  .install-block + .install-block { border-inline-start: 0; padding-inline-start: 0; padding-block-start: 28px; border-block-start: 1px solid var(--line); }
  .faq-body { grid-template-columns: 1fr; }
  .site-footer { flex-wrap: wrap; gap: 10px; }
  .site-footer > a:last-child { margin-inline-start: 0; }
}
@media (max-width: 420px) {
  .desktop-content { grid-template-columns: 1fr; }
  .demo-qr { inline-size: 120px; justify-self: center; }
  .demo-message { text-align: center; }
  .hero-lede { font-size: 15px; }
  .mobile-install img { inline-size: 100px; }
  .site-header nav a[href="#install"] { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 0s !important; animation: none !important; }
  .button:active, .demo-button:active { transform: none; }
}