/* 脆皮鸭 CPYOS — project site.
   Paper-first typography, thin rules, mono labels and one duck. Light by
   default, follows prefers-color-scheme unless the reader chooses a theme. */

:root {
  color-scheme: light;
  --paper: #f4f1e9;
  --paper-2: #ece8dd;
  --card: #fbf9f3;
  --ink: #121210;
  --ink-soft: #37352f;
  --muted: #706d64;
  --line: #d4cfc2;
  --line-strong: #a9a396;
  --water: #dbe6e2;
  --water-ink: #3f5b55;
  --accent: #121210;
  --accent-ink: #f8f5ec;
  --danger: #8c3b2e;
  --serif: "Songti SC", "Noto Serif SC", "Source Han Serif SC", "STSong", serif;
  --sans: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --mono: ui-monospace, "SF Mono", "Cascadia Mono", Menlo, monospace;
  --shadow: 0 24px 70px rgb(20 20 16 / 10%);
  --radius: 18px;
}

html[data-theme="dark"] {
  color-scheme: dark;
  --paper: #0f0f0d;
  --paper-2: #151513;
  --card: #171715;
  --ink: #ece9e0;
  --ink-soft: #cbc7bd;
  --muted: #9b978d;
  --line: #2b2a26;
  --line-strong: #4a483f;
  --water: #182421;
  --water-ink: #a9c9c0;
  --accent: #ece9e0;
  --accent-ink: #11110f;
  --danger: #d08a7e;
  --shadow: 0 24px 70px rgb(0 0 0 / 45%);
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) {
    color-scheme: dark;
    --paper: #0f0f0d;
    --paper-2: #151513;
    --card: #171715;
    --ink: #ece9e0;
    --ink-soft: #cbc7bd;
    --muted: #9b978d;
    --line: #2b2a26;
    --line-strong: #4a483f;
    --water: #182421;
    --water-ink: #a9c9c0;
    --accent: #ece9e0;
    --accent-ink: #11110f;
    --danger: #d08a7e;
    --shadow: 0 24px 70px rgb(0 0 0 / 45%);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
::selection { background: var(--ink); color: var(--paper); }
a { color: inherit; }
img { display: block; max-width: 100%; height: auto; }
button, input { font: inherit; }
:focus-visible { outline: 2px solid var(--ink); outline-offset: 4px; }

.wrap { width: min(1180px, calc(100% - 48px)); margin-inline: auto; }
.mono { font-family: var(--mono); font-size: 11px; letter-spacing: .16em; text-transform: uppercase; }
.muted { color: var(--muted); }
.serif { font-family: var(--serif); }

.skip {
  position: absolute; left: -9999px; top: 0; padding: 10px 14px;
  background: var(--ink); color: var(--paper); z-index: 100;
}
.skip:focus { left: 16px; top: 16px; }

/* ---------- top bar ---------- */
.top {
  position: sticky; top: 0; z-index: 40;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}
.top .wrap {
  height: 68px; display: flex; align-items: center; gap: 26px;
}
.brand {
  display: flex; align-items: center; gap: 11px;
  text-decoration: none; font-family: var(--serif); font-size: 19px; font-weight: 600;
  letter-spacing: .02em; white-space: nowrap;
}
.brand svg { width: 34px; height: 26px; color: var(--ink); }
.brand small { font-family: var(--mono); font-size: 10px; letter-spacing: .22em; color: var(--muted); }
.nav { display: flex; align-items: center; gap: 22px; margin-left: auto; }
.nav a { text-decoration: none; font-size: 13px; color: var(--muted); }
.nav a:hover { color: var(--ink); }
.nav .gh { color: var(--ink); border-bottom: 1px solid var(--line-strong); padding-bottom: 2px; }
.theme {
  width: 38px; height: 38px; display: grid; place-items: center;
  border: 1px solid var(--line-strong); border-radius: 50%;
  background: transparent; color: var(--ink); cursor: pointer;
}
.theme:hover { background: var(--paper-2); }
.theme svg { width: 17px; height: 17px; }
@media (max-width: 860px) { .nav a:not(.gh) { display: none; } }

/* ---------- hero ---------- */
.hero { padding: 72px 0 48px; border-bottom: 1px solid var(--line); overflow: hidden; }
.hero .wrap {
  display: grid; grid-template-columns: minmax(0, 1.18fr) minmax(300px, .82fr);
  gap: 58px; align-items: center;
}
.kicker { display: flex; flex-wrap: wrap; gap: 10px 18px; align-items: center; color: var(--muted); }
.kicker .dot { width: 5px; height: 5px; border-radius: 50%; background: var(--ink); }
.hero h1 {
  margin: 20px 0 2px; font-family: var(--serif); font-weight: 600;
  font-size: clamp(64px, 10vw, 118px); line-height: .92; letter-spacing: .01em;
}
.hero h1 .en {
  display: block; font-family: var(--mono); font-size: clamp(13px, 1.5vw, 17px);
  font-weight: 400; letter-spacing: .46em; color: var(--muted); margin-top: 16px;
}
.lede {
  margin: 28px 0 0; max-width: 620px; font-family: var(--serif);
  font-size: clamp(19px, 2.2vw, 25px); line-height: 1.72;
}
.lede em { font-style: normal; border-bottom: 2px solid var(--ink); }
.hero p.en-lede { margin: 16px 0 0; max-width: 560px; color: var(--muted); font-size: 13px; line-height: 1.7; }
.cta { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 30px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  min-height: 46px; padding: 0 20px; border-radius: 999px;
  border: 1px solid var(--ink); background: transparent; color: var(--ink);
  text-decoration: none; font-size: 14px; font-weight: 500; cursor: pointer;
  transition: background .18s ease, color .18s ease, transform .18s ease;
}
.btn:hover { background: var(--ink); color: var(--paper); transform: translateY(-1px); }
.btn.solid { background: var(--ink); color: var(--paper); }
.btn.solid:hover { background: var(--ink-soft); color: var(--paper); }
.btn small { font-family: var(--mono); font-size: 10px; letter-spacing: .1em; opacity: .7; }

.device-stage { position: relative; display: grid; place-items: center; min-height: 470px; }
.device-stage::before {
  content: ""; position: absolute; inset: 8% 0 6%;
  background: radial-gradient(ellipse at 50% 60%, var(--water), transparent 68%);
  border-radius: 50%;
}
.waterline { position: absolute; left: 0; right: 0; bottom: 30px; height: 1px; background: var(--line-strong); }
.ripple { position: absolute; left: 50%; bottom: 6px; width: 210px; height: 54px; transform: translateX(-50%); color: var(--water-ink); opacity: .75; }
.device {
  position: relative; z-index: 1; width: min(272px, 74%);
  padding: 10px; border: 2px solid var(--ink); border-radius: 20px;
  background: var(--card); box-shadow: var(--shadow);
  transform: rotate(-1.2deg);
}
.device img { border-radius: 11px; }
.device .cap {
  display: flex; justify-content: space-between; gap: 8px;
  padding: 9px 4px 1px; font-family: var(--mono); font-size: 9px; letter-spacing: .12em; color: var(--muted);
}

/* Interface structure mockups. These are CSS drawings, never device captures:
   no book titles, no Wi-Fi SSIDs and no screenshots are shipped. */
.mock-screen {
  aspect-ratio: 684 / 1216; display: flex; flex-direction: column; gap: 8px;
  padding: 11px; overflow: hidden; background: var(--paper); color: var(--ink);
  border: 1px solid var(--line-strong); border-radius: 8px;
}
.device .mock-screen { border-radius: 11px; }
.mock-status {
  display: flex; justify-content: space-between; align-items: baseline;
  padding-bottom: 5px; border-bottom: 1px solid var(--line);
  font-family: var(--mono); font-size: 6px; letter-spacing: .04em; color: var(--muted);
}
.mock-logo { font-family: var(--serif); font-size: 11px; font-weight: 600; color: var(--ink); }
.mock-hero { display: flex; flex-direction: column; gap: 5px; padding: 8px; border: 1px solid var(--line); border-radius: 6px; }
.mock-kicker { font-family: var(--mono); font-size: 5px; letter-spacing: .12em; color: var(--muted); text-transform: uppercase; }
.mock-hero b { font-family: var(--serif); font-size: 13px; }
.mock-sub { font-size: 6px; color: var(--muted); }
.mock-bar { display: block; height: 4px; overflow: hidden; background: var(--paper-2); border-radius: 2px; }
.mock-bar i { display: block; height: 100%; background: var(--ink); }
.mock-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 5px; flex: 1; }
.mock-grid span, .mock-covers i { display: block; border: 1px solid var(--line); border-radius: 3px; background: var(--card); }
.mock-covers { display: grid; grid-template-columns: repeat(3, 1fr); gap: 5px; flex: 1; }
.mock-tabs { display: flex; gap: 6px; padding-bottom: 4px; border-bottom: 1px solid var(--line); font-size: 5.5px; color: var(--muted); }
.mock-tabs b { color: var(--ink); border-bottom: 1px solid var(--ink); }
.mock-list { display: flex; flex-direction: column; gap: 4px; flex: 1; }
.mock-list span { padding: 4px 0; border-bottom: 1px solid var(--line); font-size: 6.5px; }
.mock-lines { display: flex; flex-direction: column; gap: 5px; flex: 1; padding-top: 4px; }
.mock-lines i { height: 3px; background: var(--line); border-radius: 2px; }
.mock-lines i:nth-child(3n) { width: 70%; }
.mock-nav {
  display: flex; justify-content: space-between; padding-top: 5px;
  border-top: 1px solid var(--line); font-family: var(--mono);
  font-size: 5px; letter-spacing: .02em; color: var(--muted);
}
@media (max-width: 900px) {
  .hero .wrap { grid-template-columns: 1fr; gap: 26px; }
  .device-stage { min-height: 400px; }
  .hero { padding-top: 48px; }
}

/* ---------- section shell ---------- */
section { padding: 82px 0; border-bottom: 1px solid var(--line); }
.sec-head {
  display: grid; grid-template-columns: 150px 1fr; gap: 24px;
  align-items: baseline; margin-bottom: 38px;
}
.sec-head .no { color: var(--muted); padding-top: 8px; }
.sec-head h2 {
  margin: 0; font-family: var(--serif); font-weight: 600;
  font-size: clamp(30px, 4vw, 44px); line-height: 1.2; letter-spacing: .01em;
}
.sec-head h2 span { display: block; font-family: var(--mono); font-size: 11px; letter-spacing: .24em; color: var(--muted); margin-top: 9px; font-weight: 400; }
@media (max-width: 720px) { .sec-head { grid-template-columns: 1fr; gap: 8px; } }

/* ---------- features ---------- */
.features { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); border-top: 1px solid var(--line); }
.feature {
  display: grid; grid-template-columns: 52px 1fr; gap: 16px;
  padding: 26px 30px 30px 0; border-bottom: 1px solid var(--line);
}
.feature:nth-child(odd) { border-right: 1px solid var(--line); padding-right: 38px; }
.feature:nth-child(even) { padding-left: 38px; }
.feature .idx { font-family: var(--mono); font-size: 11px; letter-spacing: .16em; color: var(--muted); padding-top: 6px; }
.feature h3 { margin: 0 0 8px; font-family: var(--serif); font-size: 23px; font-weight: 600; }
.feature p { margin: 0; color: var(--ink-soft); font-size: 14px; line-height: 1.8; }
.tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 13px; }
.tags span { font-family: var(--mono); font-size: 9.5px; letter-spacing: .1em; color: var(--muted); border: 1px solid var(--line); border-radius: 999px; padding: 3px 8px; }
@media (max-width: 760px) {
  .features { grid-template-columns: 1fr; }
  .feature:nth-child(odd), .feature:nth-child(even) { border-right: 0; padding: 24px 0; }
}

/* ---------- principles ---------- */
.principles { display: grid; grid-template-columns: repeat(3, 1fr); border: 1px solid var(--line); background: var(--line); gap: 1px; }
.principle { background: var(--card); padding: 30px 28px 36px; }
.principle .n { font-family: var(--mono); font-size: 11px; letter-spacing: .2em; color: var(--muted); }
.principle h3 { font-family: var(--serif); font-size: 27px; margin: 18px 0 12px; font-weight: 600; }
.principle p { margin: 0; color: var(--ink-soft); font-size: 14px; line-height: 1.85; }
@media (max-width: 800px) { .principles { grid-template-columns: 1fr; } }

/* ---------- screens ---------- */
.gallery { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 26px; align-items: start; }
.shot { margin: 0; }
.shot .frame { padding: 8px; border: 1px solid var(--line-strong); border-radius: 12px; background: var(--card); }
.shot img { border-radius: 6px; }
.shot figcaption { margin-top: 13px; font-size: 12px; line-height: 1.65; color: var(--muted); }
.shot figcaption b { display: block; color: var(--ink); font-weight: 600; font-size: 13px; margin-bottom: 3px; }
@media (max-width: 980px) { .gallery { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 620px) { .gallery { grid-template-columns: repeat(2, 1fr); } }

/* ---------- specs ---------- */
.specs { width: 100%; border-collapse: collapse; font-size: 14px; }
.specs th, .specs td { text-align: left; padding: 13px 14px 13px 0; border-bottom: 1px solid var(--line); vertical-align: top; }
.specs th { width: 190px; font-weight: 500; color: var(--muted); font-family: var(--mono); font-size: 10.5px; letter-spacing: .14em; text-transform: uppercase; }
.specs td { color: var(--ink-soft); }
.specs td b { color: var(--ink); font-weight: 600; }
.specs tr:last-child th, .specs tr:last-child td { border-bottom: 0; }

/* ---------- install ---------- */
.install-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; align-items: start; }
.panel { border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); padding: 28px; }
.panel h3 { margin: 0 0 14px; font-family: var(--serif); font-size: 24px; font-weight: 600; }
.panel p { margin: 0 0 12px; font-size: 14px; line-height: 1.8; color: var(--ink-soft); }
.panel ol, .panel ul { margin: 0; padding-left: 20px; color: var(--ink-soft); font-size: 14px; line-height: 1.85; }
.panel li + li { margin-top: 6px; }
.status {
  display: flex; flex-wrap: wrap; gap: 8px 18px; align-items: baseline;
  padding-bottom: 16px; margin-bottom: 18px; border-bottom: 1px solid var(--line);
}
.status .v { font-family: var(--serif); font-size: 34px; font-weight: 600; line-height: 1; }
.status .date { font-family: var(--mono); font-size: 10.5px; letter-spacing: .12em; color: var(--muted); }
.notes { margin: 16px 0 0; padding: 0; list-style: none; }
.notes li { position: relative; padding-left: 18px; font-size: 13.5px; line-height: 1.8; color: var(--ink-soft); }
.notes li::before { content: "·"; position: absolute; left: 2px; color: var(--ink); }
.install-actions { display: grid; gap: 12px; margin-top: 18px; }
.install-actions .btn { width: 100%; min-height: 54px; justify-content: space-between; padding-inline: 22px; }
.install-actions .btn .arrow { font-family: var(--mono); font-size: 15px; }
.warn {
  border-left: 2px solid var(--danger); padding: 10px 0 10px 14px;
  color: var(--ink-soft); font-size: 13px; line-height: 1.75; margin: 16px 0 0;
}
.downloads { display: flex; flex-wrap: wrap; gap: 8px 18px; margin-top: 18px; font-size: 12.5px; }
.downloads a { color: var(--ink); text-decoration: underline; text-underline-offset: 3px; text-decoration-color: var(--line-strong); }
.sha { display: flex; align-items: center; gap: 8px; margin-top: 14px; font-family: var(--mono); font-size: 10.5px; color: var(--muted); word-break: break-all; }
.sha button { border: 1px solid var(--line); background: transparent; color: var(--muted); border-radius: 999px; padding: 3px 8px; font-size: 9.5px; cursor: pointer; }
.sha button:hover { color: var(--ink); border-color: var(--line-strong); }
@media (max-width: 880px) { .install-grid { grid-template-columns: 1fr; } }

/* ---------- credits ---------- */
.credits { display: grid; grid-template-columns: 1fr 1fr; gap: 44px; }
.credits h3 { margin: 0 0 12px; font-family: var(--serif); font-size: 21px; font-weight: 600; }
.credits p, .credits li { font-size: 13px; line-height: 1.8; color: var(--ink-soft); }
.credits ul { margin: 0; padding-left: 18px; }
.credits li + li { margin-top: 7px; }
.credits a { color: var(--ink); text-underline-offset: 3px; }
.kiikoread {
  margin-top: 28px; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 24px; background: var(--water); color: var(--ink);
}
.kiikoread b { font-family: var(--mono); font-size: 10px; letter-spacing: .14em; color: var(--water-ink); display: block; margin-bottom: 8px; }
.kiikoread p { margin: 0; color: var(--ink-soft); }
@media (max-width: 800px) { .credits { grid-template-columns: 1fr; } }

/* ---------- footer ---------- */
footer { padding: 38px 0 54px; font-size: 12px; color: var(--muted); }
footer .wrap { display: flex; flex-wrap: wrap; gap: 14px 28px; align-items: baseline; justify-content: space-between; }
footer a { color: var(--ink); text-decoration: none; border-bottom: 1px solid var(--line-strong); }
footer .duckfoot { display: flex; align-items: center; gap: 10px; }
footer .duckfoot svg { width: 30px; height: 22px; }

/* ---------- reveal ---------- */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity .6s ease, transform .6s ease; }
.reveal.on { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .btn:hover { transform: none; }
}

/* Phones (390 px class). The desktop width is fluid, but the brand row, the
   64 px display type and the spec table's fixed label column all need a
   second, narrower set of rules. */
@media (max-width: 520px) {
  .wrap { width: calc(100% - 32px); }
  .top .wrap { gap: 12px; }
  .brand { font-size: 16px; gap: 8px; }
  .brand svg { width: 28px; height: 22px; }
  .brand small { display: none; }
  .nav { gap: 12px; }
  .nav .gh { font-size: 12px; }
  .theme { width: 34px; height: 34px; }
  .hero { padding-top: 40px; }
  .hero h1 { font-size: 56px; }
  .hero h1 .en { letter-spacing: .3em; }
  .lede { font-size: 18px; overflow-wrap: anywhere; }
  .kicker { display: block; line-height: 2; }
  .kicker .dot { display: inline-block; vertical-align: middle; margin: 0 8px; }
  .device-stage { min-height: 360px; }
  .device { width: min(250px, 78%); }
  .specs th { width: 108px; font-size: 9px; }
  .specs td { font-size: 13px; }
  .panel { padding: 22px; }
  .install-actions .btn { padding-inline: 14px; font-size: 13px; }
  .gallery { gap: 16px; }
  footer .wrap { flex-direction: column; }
}