:root {
  --paper: #f7f7f3;
  --white: #ffffff;
  --ink: #1e2221;
  --muted: #686f6c;
  --line: #dfe2dc;
  --coral: #d96552;
  --coral-dark: #ad4537;
  --green: #2f675a;
  --blue-soft: #e8f0f3;
  --yellow-soft: #f4e8b9;
  --shadow: 0 18px 50px rgba(31, 39, 36, 0.12);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Microsoft YaHei UI", "PingFang SC", "Noto Sans CJK SC", system-ui, sans-serif;
  letter-spacing: 0;
}
a { color: inherit; text-decoration: none; }
button, input { font: inherit; letter-spacing: 0; }
button { cursor: pointer; }

.site-header {
  position: fixed;
  z-index: 30;
  top: 0;
  left: 0;
  width: 100%;
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(20px, 4vw, 64px);
  background: rgba(247, 247, 243, 0.94);
  border-bottom: 1px solid rgba(42, 49, 46, 0.12);
  backdrop-filter: blur(14px);
}
.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 800; }
.brand-mark {
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--ink);
  border-radius: 6px;
  font-family: Georgia, serif;
}
nav { display: flex; align-items: center; gap: 28px; font-size: 14px; }
nav a:hover { color: var(--coral-dark); }
.nav-chat { border: 0; color: white; background: var(--green); padding: 10px 16px; border-radius: 6px; }

.hero {
  position: relative;
  min-height: min(860px, 92vh);
  padding: 130px clamp(24px, 7vw, 112px) 76px;
  overflow: hidden;
  background: var(--paper);
  border-bottom: 1px solid var(--line);
}
.hero-copy { position: relative; z-index: 2; width: min(660px, 55vw); padding-top: clamp(70px, 11vh, 130px); }
.eyebrow { margin: 0 0 16px; color: var(--green); font-size: 13px; font-weight: 800; text-transform: uppercase; }
h1 { margin: 0; font-size: 104px; line-height: 0.94; font-family: Georgia, "Times New Roman", serif; font-weight: 500; }
h1 span { display: block; }
.hero-dedication { margin-top: 15px; color: var(--green); font-family: "Microsoft YaHei UI", "PingFang SC", sans-serif; font-size: 46px; font-weight: 800; line-height: 1.18; }
.hero-summary { max-width: 590px; margin: 30px 0 0; color: #4d5552; font-size: 20px; line-height: 1.8; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }
.button {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid transparent;
  border-radius: 6px;
  padding: 0 20px;
  font-weight: 800;
  transition: transform 160ms ease, background 160ms ease, border-color 160ms ease;
}
.button:hover { transform: translateY(-2px); }
.button.primary { color: white; background: var(--coral); }
.button.primary:hover { background: var(--coral-dark); }
.button.secondary { color: var(--ink); background: var(--white); border-color: #cfd3ce; }
.button.full { width: 100%; }
.hero-meta { display: flex; gap: 36px; margin: 42px 0 0; }
.hero-meta div { display: grid; gap: 5px; }
.hero-meta dt { color: var(--muted); font-size: 12px; }
.hero-meta dd { margin: 0; font-size: 14px; font-weight: 800; }
.hero-visual { position: absolute; z-index: 1; right: clamp(0px, 4vw, 72px); bottom: 0; width: min(47vw, 630px); height: calc(100% - 72px); display: flex; align-items: flex-end; justify-content: center; }
.hero-visual img { position: relative; z-index: 2; max-width: 100%; max-height: 92%; width: auto; object-fit: contain; transform-origin: 50% 100%; animation: hero-breathe 5.6s ease-in-out infinite; filter: drop-shadow(0 24px 26px rgba(29, 35, 32, 0.18)); }
.character-shadow { position: absolute; z-index: 0; bottom: 3%; width: 54%; height: 5%; border-radius: 50%; background: rgba(27, 34, 31, 0.18); filter: blur(12px); }
.speech-sample { position: absolute; z-index: 4; top: 24%; left: 1%; padding: 12px 16px; border: 1px solid #d9dcd7; border-radius: 6px; color: var(--ink); background: white; box-shadow: var(--shadow); font-weight: 800; cursor: pointer; touch-action: manipulation; -webkit-tap-highlight-color: transparent; user-select: none; }
.speech-sample:focus-visible { outline: 3px solid rgba(47, 103, 90, 0.26); outline-offset: 3px; }
.speech-sample::after { content: ""; position: absolute; right: -7px; bottom: 10px; width: 12px; height: 12px; background: white; border-top: 1px solid #d9dcd7; border-right: 1px solid #d9dcd7; transform: rotate(45deg); }
.next-section { position: absolute; z-index: 4; bottom: 26px; left: clamp(24px, 7vw, 112px); display: flex; gap: 12px; color: var(--muted); font-size: 13px; }

.story-band, .download-band, .features-band, .help-band { padding: 92px clamp(24px, 7vw, 112px); }
.story-band { background: var(--blue-soft); }
.story-heading { max-width: 820px; }
.story-lines { border-top: 1px solid rgba(30, 34, 33, 0.18); }
.story-lines article { display: grid; grid-template-columns: 110px 330px 1fr; gap: 24px; align-items: baseline; padding: 30px 0; border-bottom: 1px solid rgba(30, 34, 33, 0.18); }
.story-lines span { color: var(--coral-dark); font-family: Georgia, serif; font-size: 15px; }
.story-lines h3 { margin: 0; font-size: 24px; }
.story-lines p { max-width: 680px; margin: 0; color: #4d5653; line-height: 1.8; }
.download-band { background: var(--white); }
.section-heading { max-width: 720px; margin-bottom: 42px; }
.section-heading.compact { margin-bottom: 36px; }
.section-heading h2 { margin: 0; font-family: Georgia, "Times New Roman", serif; font-size: 58px; font-weight: 500; line-height: 1.08; }
.section-heading > p:last-child { color: var(--muted); line-height: 1.7; }
.download-grid { display: grid; grid-template-columns: 1.25fr 1fr 1fr; gap: 18px; }
.download-item { min-height: 330px; display: flex; flex-direction: column; padding: 26px; border: 1px solid var(--line); border-radius: 8px; background: #fbfbf8; }
.download-item.featured { border-top: 5px solid var(--coral); background: #fffaf7; }
.platform-line { display: flex; align-items: center; gap: 9px; color: var(--muted); font-size: 13px; }
.platform-line strong { margin-left: auto; color: var(--coral-dark); }
.platform-icon { width: 28px; height: 28px; display: grid; place-items: center; border-radius: 5px; color: white; background: #2f5ca8; font-weight: 900; }
.platform-icon.apple { background: var(--ink); }
.download-item h3 { margin: 24px 0 10px; font-size: 28px; }
.download-item p { margin: 0; color: var(--muted); line-height: 1.75; }
.download-detail { display: flex; gap: 12px; margin: auto 0 18px; color: var(--green); font-size: 12px; font-weight: 800; }
.download-note { margin: 22px 0 0; color: var(--muted); font-size: 13px; }

.features-band { background: var(--blue-soft); }
.feature-list { border-top: 1px solid rgba(30, 34, 33, 0.18); }
.feature-list article { display: grid; grid-template-columns: 70px 220px 1fr; gap: 22px; align-items: baseline; padding: 28px 0; border-bottom: 1px solid rgba(30, 34, 33, 0.18); }
.feature-list span { color: var(--coral-dark); font-family: Georgia, serif; }
.feature-list h3 { margin: 0; font-size: 21px; }
.feature-list p { margin: 0; color: #4d5653; line-height: 1.7; }

.help-band { background: #f2ead0; }
.faq-list { max-width: 900px; }
details { border-top: 1px solid rgba(30, 34, 33, 0.24); }
details:last-child { border-bottom: 1px solid rgba(30, 34, 33, 0.24); }
summary { position: relative; padding: 22px 40px 22px 0; list-style: none; font-weight: 800; cursor: pointer; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; position: absolute; right: 8px; top: 18px; font-size: 24px; font-weight: 400; }
details[open] summary::after { content: "−"; }
details p { max-width: 760px; margin: 0; padding: 0 40px 24px 0; color: #555b58; line-height: 1.8; }
.ask-button { margin-top: 30px; }

footer { min-height: 150px; display: flex; align-items: center; gap: 30px; padding: 30px clamp(24px, 7vw, 112px); color: #dce1de; background: var(--ink); }
footer p { margin-left: auto; color: #aeb6b2; }
footer > a:last-child { color: #aeb6b2; font-size: 13px; }

.chat-launcher { position: fixed; z-index: 45; right: 22px; bottom: 22px; min-height: 48px; display: flex; align-items: center; gap: 9px; padding: 0 18px; border: 0; border-radius: 24px; color: white; background: var(--green); box-shadow: var(--shadow); font-weight: 800; }
.chat-dot { width: 8px; height: 8px; border-radius: 50%; background: #92e2a6; box-shadow: 0 0 0 4px rgba(146, 226, 166, 0.16); }
.chat-panel { position: fixed; z-index: 60; right: 22px; bottom: 22px; width: min(390px, calc(100vw - 28px)); height: min(620px, calc(100vh - 44px)); display: flex; flex-direction: column; overflow: hidden; border: 1px solid #d8ddd8; border-radius: 8px; background: white; box-shadow: 0 28px 80px rgba(20, 27, 24, 0.24); transform: translateY(24px); opacity: 0; pointer-events: none; transition: 180ms ease; }
.chat-panel.open { transform: translateY(0); opacity: 1; pointer-events: auto; }
.chat-panel > header { height: 72px; display: flex; align-items: center; justify-content: space-between; padding: 0 18px; color: white; background: var(--green); }
.chat-panel header div { display: grid; gap: 3px; }
.chat-panel header span { color: #d4e7e1; font-size: 12px; }
.chat-panel header button { width: 34px; height: 34px; border: 0; color: white; background: transparent; font-size: 26px; }
.chat-messages { flex: 1; overflow-y: auto; display: flex; flex-direction: column; gap: 10px; padding: 18px; background: #f7f8f5; }
.message { max-width: 86%; padding: 11px 13px; border-radius: 8px; line-height: 1.6; font-size: 14px; }
.message.bot { align-self: flex-start; border: 1px solid #e0e4df; background: white; }
.message.user { align-self: flex-end; color: white; background: var(--coral); }
.message.pending { color: var(--muted); }
.quick-questions { display: flex; gap: 7px; overflow-x: auto; padding: 10px 14px; border-top: 1px solid #e2e5e0; }
.quick-questions button { flex: 0 0 auto; border: 1px solid #d7dcd6; border-radius: 16px; padding: 7px 10px; color: #4d5652; background: white; font-size: 12px; }
.chat-form { display: grid; grid-template-columns: 1fr 64px; gap: 8px; padding: 12px 14px; border-top: 1px solid #e2e5e0; }
.chat-form input { min-width: 0; height: 42px; border: 1px solid #ccd2cc; border-radius: 6px; padding: 0 11px; outline: none; }
.chat-form input:focus { border-color: var(--green); box-shadow: 0 0 0 3px rgba(47, 103, 90, 0.12); }
.chat-form button { border: 0; border-radius: 6px; color: white; background: var(--green); font-weight: 800; }
.chat-status { margin: 0; padding: 0 14px 11px; color: #858c88; font-size: 11px; }
.chat-backdrop { display: none; }
.secret-letter { position: fixed; z-index: 80; inset: 0; display: grid; place-items: center; padding: 24px; background: rgba(20, 26, 24, 0.62); opacity: 0; visibility: hidden; pointer-events: none; transition: opacity 180ms ease, visibility 180ms ease; }
.secret-letter.open, .secret-letter:target { opacity: 1; visibility: visible; pointer-events: auto; }
.letter-sheet { position: relative; width: min(620px, 100%); max-height: calc(100vh - 48px); overflow-y: auto; padding: 54px 58px 48px; border-top: 5px solid var(--coral); border-radius: 8px; background: #fffefa; box-shadow: 0 30px 90px rgba(14, 20, 18, 0.34); transform: translateY(18px); transition: transform 180ms ease; }
.secret-letter.open .letter-sheet, .secret-letter:target .letter-sheet { transform: translateY(0); }
.letter-sheet h2 { max-width: 460px; margin: 0; font-family: Georgia, "Times New Roman", serif; font-size: 42px; font-weight: 500; line-height: 1.2; }
.letter-copy { margin-top: 32px; padding-top: 26px; border-top: 1px solid var(--line); }
.letter-copy p { margin: 0 0 18px; color: #4d5552; font-size: 17px; line-height: 1.9; }
.letter-signature { margin: 34px 0 0; color: var(--green); font-weight: 800; text-align: right; }
.letter-close { position: absolute; top: 16px; right: 16px; width: 38px; height: 38px; display: grid; place-items: center; border: 0; border-radius: 50%; color: var(--ink); background: transparent; font-size: 28px; line-height: 1; }
.letter-close:hover { background: #f0f1ed; }
body.secret-open { overflow: hidden; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

@keyframes hero-breathe {
  0%, 100% { transform: translateY(0) scale(1); }
  50% { transform: translateY(-4px) scale(1.006, 0.995); }
}

@media (max-width: 900px) {
  nav a { display: none; }
  .hero { min-height: 820px; padding-top: 96px; }
  .hero-copy { width: 100%; padding-top: 30px; }
  h1 { font-size: 82px; }
  .hero-dedication { font-size: 40px; }
  .hero-summary { max-width: 58%; font-size: 16px; }
  .hero-visual { right: -9%; width: 62%; height: 68%; }
  .speech-sample { top: 18%; left: -4%; }
  .download-grid { grid-template-columns: 1fr; }
  .download-item { min-height: 280px; }
  .story-lines article { grid-template-columns: 80px 260px 1fr; }
}

@media (max-width: 620px) {
  .site-header { height: 60px; padding: 0 16px; }
  .brand { font-size: 14px; }
  .brand-mark { width: 30px; height: 30px; }
  nav { gap: 8px; }
  .nav-chat { padding: 9px 12px; }
  .hero { min-height: 780px; padding: 92px 18px 62px; }
  .hero-copy { padding-top: 0; }
  h1 { max-width: 100%; font-size: 60px; }
  .hero-dedication { margin-top: 9px; font-size: 30px; }
  .hero-summary { max-width: 100%; margin-top: 18px; padding-right: 8px; font-size: 15px; line-height: 1.7; }
  .hero-actions { margin-top: 22px; }
  .button { min-height: 46px; padding: 0 15px; font-size: 14px; }
  .hero-meta { gap: 18px; margin-top: 24px; }
  .hero-meta div:nth-child(3) { display: none; }
  .hero-visual { right: -18%; bottom: 18px; width: 82%; height: 50%; }
  .speech-sample { top: 2%; left: 2%; font-size: 13px; }
  .next-section { bottom: 18px; left: 18px; }
  .story-band, .download-band, .features-band, .help-band { padding: 68px 18px; }
  .section-heading h2 { font-size: 40px; }
  .story-lines article { grid-template-columns: 54px 1fr; gap: 12px; }
  .story-lines article p { grid-column: 2; }
  .story-lines h3 { font-size: 20px; }
  .feature-list article { grid-template-columns: 42px 1fr; gap: 12px; }
  .feature-list article p { grid-column: 2; }
  footer { flex-wrap: wrap; gap: 18px; padding: 30px 18px; }
  footer p { width: 100%; margin: 0; order: 3; }
  .chat-launcher { right: 14px; bottom: 14px; }
  .chat-panel { right: 7px; bottom: 7px; width: calc(100vw - 14px); height: calc(100vh - 14px); }
  body.chat-open, body.secret-open { overflow: hidden; }
  .chat-backdrop { position: fixed; z-index: 55; inset: 0; background: rgba(19, 24, 22, 0.38); }
  body.chat-open .chat-backdrop { display: block; }
  .secret-letter { padding: 12px; }
  .letter-sheet { max-height: calc(100vh - 24px); padding: 48px 24px 34px; }
  .letter-sheet h2 { font-size: 34px; }
  .letter-copy p { font-size: 15px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}