@font-face {
  font-family: "Yujian Serif";
  src: url(assets/fonts/yujian-serif-400.woff2) format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}

@font-face {
  font-family: "Yujian Serif";
  src: url(assets/fonts/yujian-serif-600.woff2) format("woff2");
  font-weight: 600;
  font-style: normal;
  font-display: swap;
}

:root {
  color-scheme: light;
  --paper:       #FDFCFB;               /* 纸面，整页底色（B4 纯平背景） */
  --ink:         #27323A;               /* 墨色：正文、按钮、链接 */
  --ink-muted:   #6B757E;               /* Hero 标题渐变尾色（B5） */
  --ink-2:       rgba(39, 50, 58, .66); /* 次要文字 */
  --ink-3:       rgba(39, 50, 58, .44); /* 注释、出处、页脚 */
  --light:       #EDB05C;               /* 暖光：品牌细线、释义左边线、焦点 */
  --light-soft:  rgba(237, 176, 92, .18);
  --amber:       #966118;               /* 正在查的词 */
  --amber-soft:  rgba(150, 97, 24, .14);
  --cyan-line:   #4A8B9C;               /* 仅用于划线色圆点示意 */
  --sakura-line: #D47A8C;               /* 仅用于划线色圆点示意 */
  --hairline:    rgba(39, 50, 58, .10);
  --well:        rgba(39, 50, 58, .04); /* 嵌在纸里的浅色块（B4 纯平） */
  --well-hover:  rgba(39, 50, 58, .07);

  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-en-serif: ui-serif, "New York", "Iowan Old Style", Georgia, serif;

  /* B7 & design-to-motion B6 Motion curves */
  --ease-fluid: cubic-bezier(0.32, 0.72, 0, 1);
  --e:          cubic-bezier(0.16, 1, 0.3, 1);
  --e2:         cubic-bezier(0.33, 1, 0.68, 1);
  --io:         cubic-bezier(0.65, 0, 0.35, 1);
}

*,
*::before,
*::after {
  box-sizing: border-box;
  font-style: normal;
}

html {
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  margin: 0;
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 24px;
  position: relative;
}

.page {
  position: relative;
  overflow: clip;
}

/* B10. Skip link for keyboard accessibility */
.skip-link {
  position: fixed;
  top: 12px;
  left: 16px;
  z-index: 200;
  padding: 8px 16px;
  border-radius: 9999px;
  background-color: var(--ink);
  color: var(--paper);
  font-size: 14px;
  line-height: 20px;
  font-weight: 600;
  text-decoration: none;
  transform: translateY(-80px);
  transition: transform 400ms var(--ease-fluid);
}

.skip-link:focus {
  transform: translateY(0);
}

.clause {
  display: inline-block;
}

img,
video {
  display: block;
  max-width: 100%;
  height: auto;
}

.serif {
  font-family: "Yujian Serif", "Songti SC", serif;
}

.amber {
  color: var(--amber);
  font-weight: 600;
}

h1, h2, h3 {
  text-wrap: balance;
}

p {
  text-wrap: pretty;
}

/* 焦点与链接（B9） */
a {
  color: var(--ink);
  text-decoration: none;
}

a:hover {
  text-decoration: none;
}

:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 2px;
}

/* 版心容器（B2 Spacing: 32px desktop, 16px mobile） */
.container {
  width: min(1120px, calc(100% - 64px));
  margin-inline: auto;
  position: relative;
  z-index: 1;
}

main > .section {
  position: relative;
  padding-block: 96px; /* Spacing-900 */
}

/* 品牌细线（唯一装饰元素） */
.brand-bar {
  display: inline-block;
  width: 4px;          /* Spacing-50 */
  height: 12px;        /* Spacing-100 */
  border-radius: 9999px;
  background-color: var(--light);
  margin-right: 8px;   /* Spacing-75 */
  flex-shrink: 0;
}

/* B1 & B2 & B9: 按钮系统 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;            /* Spacing-75 */
  padding: 8px 16px;   /* Spacing-75 × Spacing-200 */
  min-height: 40px;    /* Spacing-500 */
  border-radius: 9999px;
  font-family: var(--font-sans);
  font-size: 16px;     /* text-base */
  line-height: 24px;
  font-weight: 600;
  white-space: nowrap;
  cursor: pointer;
  user-select: none;
  text-decoration: none;
  transition:
    background-color 700ms var(--ease-fluid),
    color 700ms var(--ease-fluid),
    border-color 700ms var(--ease-fluid),
    opacity 700ms var(--ease-fluid),
    transform 700ms var(--ease-fluid);
}

.btn:hover:not([aria-disabled="true"]) {
  transform: translateY(-2px);
}

.btn:active:not([aria-disabled="true"]) {
  transform: scale(0.98);
}

.btn-primary {
  background-color: var(--ink);
  color: var(--paper);
  border: 1px solid var(--ink);
}

.btn-primary:hover:not([aria-disabled="true"]) {
  opacity: 0.90;
}

.btn-secondary {
  background-color: var(--paper);
  color: var(--ink);
  border: 1px solid var(--hairline);
}

.btn-secondary:hover:not([aria-disabled="true"]) {
  background-color: var(--well);
}

.btn[aria-disabled="true"] {
  background-color: var(--well);
  color: var(--ink-2);
  border: 1px solid var(--hairline);
  cursor: default;
  opacity: 1;
  transform: none;
}

.btn-nav {
  padding: 8px 12px;   /* Spacing-75 × Spacing-100 (B2) */
  min-height: 32px;    /* Spacing-400 */
  font-size: 14px;     /* text-sm (B1) */
  line-height: 20px;
}

.btn-icon {
  flex-shrink: 0;
}

/* ==========================================================================
   B7. Fluid Island Navigation
   ========================================================================== */
.island-header {
  position: sticky;
  top: 24px;           /* Spacing-300: mt-6 detached from top */
  z-index: 60;
  display: flex;
  justify-content: center;
  padding-inline: 16px;
  pointer-events: none;
}

.island-pill {
  pointer-events: auto;
  width: max-content;
  max-width: 100%;
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: 24px;           /* Spacing-300 */
  padding: 8px 8px 8px 16px;
  border-radius: 9999px;
  background-color: rgba(253, 252, 251, 0.84);
  -webkit-backdrop-filter: blur(24px);
  backdrop-filter: blur(24px);
  border: 1px solid var(--hairline);
  box-shadow: 0 12px 32px -12px rgba(39, 50, 58, 0.10);
  transition:
    padding 700ms var(--ease-fluid),
    background-color 700ms var(--ease-fluid),
    box-shadow 700ms var(--ease-fluid);
}

.brand-link {
  display: inline-flex;
  align-items: center;
  padding: 4px 0;
}

.brand-link img {
  height: 20px;
  width: auto;
}

.island-links {
  display: flex;
  align-items: center;
  gap: 4px;            /* Spacing-50 */
}

.nav-link {
  padding: 8px 12px;   /* Spacing-75 × Spacing-100 */
  border-radius: 9999px;
  font-size: 14px;     /* text-sm */
  line-height: 20px;
  font-weight: 600;
  color: var(--ink-2);
  transition:
    color 700ms var(--ease-fluid),
    background-color 700ms var(--ease-fluid);
}

.nav-link:hover {
  color: var(--ink);
  background-color: var(--well);
}

.nav-link.is-active,
.nav-link[aria-current="true"] {
  color: var(--ink);
  background-color: var(--well);
}

.island-actions {
  display: flex;
  align-items: center;
  gap: 8px;            /* Spacing-75 */
}

/* Hamburger button (morphs into X on mobile) */
.island-menu-btn {
  display: none;
  position: relative;
  width: 32px;         /* Spacing-400 */
  height: 32px;
  padding: 0;
  border-radius: 9999px;
  border: 1px solid var(--hairline);
  background-color: var(--paper);
  color: var(--ink);
  cursor: pointer;
  align-items: center;
  justify-content: center;
  transition: background-color 700ms var(--ease-fluid);
}

.island-menu-btn:hover {
  background-color: var(--well);
}

.hamburger-line {
  position: absolute;
  width: 14px;
  height: 2px;
  border-radius: 9999px;
  background-color: var(--ink);
  transition: transform 700ms var(--ease-fluid);
}

.hamburger-line-top {
  transform: translateY(-3px) rotate(0deg);
}

.hamburger-line-bottom {
  transform: translateY(3px) rotate(0deg);
}

html.is-menu-open .hamburger-line-top {
  transform: translateY(0) rotate(45deg);
}

html.is-menu-open .hamburger-line-bottom {
  transform: translateY(0) rotate(-45deg);
}

/* Mobile Fullscreen Glass Overlay (B7) */
.mobile-nav-overlay {
  position: fixed;
  inset: 0;
  z-index: 50;
  background-color: rgba(253, 252, 251, 0.88);
  -webkit-backdrop-filter: blur(48px);
  backdrop-filter: blur(48px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 32px;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition:
    opacity 700ms var(--ease-fluid),
    visibility 0ms linear 700ms;
}

html.is-menu-open .mobile-nav-overlay {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transition:
    opacity 700ms var(--ease-fluid),
    visibility 0ms linear 0ms;
}

.mobile-nav-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;           /* Spacing-300 */
  text-align: center;
}

.mobile-nav-mask {
  overflow: hidden;
  padding: 4px 8px;
}

.mobile-nav-link,
.mobile-nav-cta-wrap .btn {
  display: inline-flex;
  font-size: 30px;     /* text-3xl */
  line-height: 36px;
  font-weight: 600;
  color: var(--ink);
  opacity: 0;
  transform: translateY(48px); /* translate-y-12 */
  transition:
    transform 700ms var(--ease-fluid),
    opacity 700ms var(--ease-fluid);
  transition-delay: 0ms;
}

.mobile-nav-cta-wrap .btn {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 24px;
  margin-top: 8px;
}

html.is-menu-open .mobile-nav-link,
html.is-menu-open .mobile-nav-cta-wrap .btn {
  opacity: 1;
  transform: translateY(0);
  transition-delay: var(--stagger, 100ms);
}

/* ==========================================================================
   B1 & B2 Typography & Section Headers
   ========================================================================== */
.eyebrow {
  margin: 0 0 16px;    /* Spacing-200 */
  font-size: 12px;     /* text-xs */
  line-height: 16px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--ink-3);
  display: inline-flex;
  align-items: center;
}

.eyebrow-center {
  justify-content: center;
}

.section-header {
  margin-bottom: 64px; /* Spacing-700 */
}

.section-header-center {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.section-title {
  margin: 0;
  font-size: 36px;     /* text-4xl */
  line-height: 40px;
  font-weight: 600;
  color: var(--ink);
  max-width: 680px;    /* B5 */
}

.section-title-center {
  text-align: center;
  margin-inline: auto;
}

.body-text {
  margin: 0;
  font-size: 16px;     /* text-base */
  line-height: 24px;
  color: var(--ink-2);
  max-width: 540px;
}

.meta-note {
  margin: 16px 0 0;    /* Spacing-200 */
  font-size: 12px;     /* text-xs */
  line-height: 16px;
  letter-spacing: 0.04em;
  color: var(--ink-3);
}

/* ==========================================================================
   B3. Nested Corner Radius Containers & Screenshots
   Outer card: rounded-3xl (24px), padding: 16px (Spacing-200)
   Inner frame: 24px - 16px = 8px (rounded-lg)
   ========================================================================== */
.stage-card,
.hero-frame-card {
  background-color: var(--well);
  border: 1px solid var(--hairline);
  border-radius: 24px; /* rounded-3xl */
  padding: 16px;       /* Spacing-200 */
}

.stage-card-compact {
  display: inline-block;
  padding: 24px;       /* Spacing-300 */
}

.stage-inner {
  position: relative;
  border-radius: 8px;  /* 24px - 16px = 8px (B3 formula) */
  overflow: hidden;
  transform: translateZ(0);
}

.shot-window {
  border-radius: 8px;  /* 24px - 16px = 8px */
  border: 1px solid var(--hairline);
  box-shadow:
    0 32px 64px -32px rgba(80, 55, 20, .22),
    0 2px 8px rgba(0, 0, 0, .04);
  background-color: var(--paper);
}

.shot-card {
  border-radius: 12px; /* rounded-xl */
  box-shadow: 0 24px 48px -20px rgba(80, 55, 20, .30);
}

/* ==========================================================================
   3.1 Hero (B5 Heading Gradient + Max Width 680px)
   ========================================================================== */
main > .section-hero {
  padding-top: 64px;   /* Spacing-700 */
  padding-bottom: 96px;/* Spacing-900 */
}

.hero-grid {
  display: grid;
  grid-template-columns: 5fr 7fr;
  align-items: center;
  gap: 48px;           /* Spacing-600 */
}

.hero-copy {
  min-width: 0;
  max-width: 680px;    /* B5 */
}

.hero-title {
  margin: 0 0 24px;    /* Spacing-300 */
  font-size: 60px;     /* text-6xl (B1) */
  line-height: 1.08;
  font-weight: 600;
  letter-spacing: 0.01em;
  max-width: 680px;    /* B5 */
  /* B5 Light theme left-to-right text gradient */
  background-image: linear-gradient(90deg, var(--ink) 0%, var(--ink-muted) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-subtitle {
  margin: 0 0 32px;    /* Spacing-400 */
  font-size: 18px;     /* text-lg (B1) */
  line-height: 28px;
  color: var(--ink-2);
  max-width: 680px;    /* B5 */
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;           /* Spacing-100 */
}

/* A2 #4 Proof Strip above the fold */
.proof-strip {
  list-style: none;
  margin: 24px 0 0;    /* Spacing-300 */
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 16px;           /* Spacing-200 */
}

.proof-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;            /* Spacing-75 */
  font-size: 12px;     /* text-xs */
  line-height: 16px;
  color: var(--ink-2);
}

.proof-dot {
  width: 6px;
  height: 6px;
  border-radius: 9999px;
  background-color: var(--light);
  flex-shrink: 0;
}

.hero-stage {
  min-width: 0;
}

.hero-composition {
  position: relative;
  padding-right: 24px; /* Spacing-300 */
  padding-bottom: 40px;/* Spacing-500 */
}

.dtm-window-wrap {
  position: relative;
  border-radius: 8px;
  overflow: hidden;
}

.hero-window {
  width: 100%;
  height: auto;
}

.hero-card-unit {
  position: absolute;
  right: 0;
  bottom: 0;
  width: 46%;
  z-index: 2;
  will-change: transform, opacity, filter;
}

.hero-card-img {
  width: 100%;
  height: auto;
}

/* ==========================================================================
   3.2 B11 Mandatory Tagline Reveal Section
   ========================================================================== */
main > .section-lead {
  padding-block: 96px; /* Spacing-900 */
}

.lead-inner {
  max-width: 680px;    /* B5 & B11 */
  margin-inline: auto;
  text-align: center;
}

.lead-en {
  margin: 0 0 24px;    /* Spacing-300 */
  font-family: var(--font-en-serif);
  font-size: 36px;     /* text-4xl (B11) */
  line-height: 40px;
  font-weight: 400;
  color: var(--ink);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  column-gap: 8px;     /* Spacing-75 */
  row-gap: 4px;        /* Spacing-50 */
}

.lead-zh {
  margin: 0 0 24px;    /* Spacing-300 */
  font-size: 24px;     /* text-2xl (B1) */
  line-height: 32px;
  font-weight: 600;
  color: var(--ink);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  column-gap: 4px;
  row-gap: 4px;
}

.lead-desc {
  margin: 0 auto;
  font-size: 16px;     /* text-base */
  line-height: 24px;
  color: var(--ink-2);
  max-width: 520px;
}

/* B11 Word-by-word scroll transition */
.tagline-word {
  display: inline-block;
  color: var(--ink);
  opacity: 1;
  transition:
    opacity 700ms var(--ease-fluid),
    color 700ms var(--ease-fluid),
    transform 700ms var(--ease-fluid);
}

.tagline-word-amber {
  color: var(--amber);
  font-weight: 600;
}

html.js-motion .tagline-word {
  opacity: 0.26;
}

html.js-motion .tagline-word.is-lit {
  opacity: 1;
}

/* ==========================================================================
   3.3 一个词的一生 #journey
   ========================================================================== */
.journey-list {
  display: flex;
  flex-direction: column;
  gap: 96px;           /* Spacing-900 */
}

.journey-item {
  display: grid;
  grid-template-columns: 5fr 7fr;
  align-items: center;
  gap: 48px;           /* Spacing-600 */
}

.journey-item-reverse {
  grid-template-columns: 7fr 5fr;
}

.journey-item-reverse .journey-copy {
  order: 2;
}

.journey-item-reverse .journey-media {
  order: 1;
}

.journey-copy {
  min-width: 0;
  max-width: 680px;
}

.chapter-eyebrow {
  margin: 0 0 12px;    /* Spacing-100 */
  font-size: 14px;     /* text-sm */
  line-height: 20px;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--ink-3);
  display: inline-flex;
  align-items: center;
}

.chapter-title {
  margin: 0 0 16px;    /* Spacing-200 */
  font-size: 30px;     /* text-3xl (B1) */
  line-height: 36px;
  font-weight: 600;
  color: var(--ink);
}

.journey-media {
  min-width: 0;
}

.journey-media-center {
  display: flex;
  justify-content: center;
}

.memory-card-wrap {
  position: relative;
}

.memory-card {
  width: min(380px, 100%);
  height: auto;
}

/* 二 · 查：完整露出带琥珀色 deliberately 的整行 */
.lookup-composition {
  position: relative;
}

.lookup-crop {
  position: relative;
  width: 100%;
  aspect-ratio: 780 / 350;
  border-radius: 8px;  /* 24px - 16px = 8px (B3) */
  border: 1px solid var(--hairline);
  box-shadow:
    0 32px 64px -32px rgba(80, 55, 20, .20),
    0 2px 8px rgba(0, 0, 0, .04);
  overflow: hidden;
  background-color: var(--paper);
}

.lookup-window-img {
  width: 153.85%;
  max-width: none;
  height: auto;
  margin-left: -26.92%;
  margin-top: -25.64%;
}

.lookup-card-wrap {
  position: relative;
  z-index: 2;
  width: min(360px, 64%);
  margin-top: -32px;   /* Spacing-400 overlap */
  margin-left: auto;
  margin-right: 16px;  /* Spacing-200 */
  will-change: transform, opacity, filter;
}

.lookup-card-img {
  width: 100%;
  height: auto;
}

/* 五 · 再遇见：带小点正文 + flip 叠在一角 */
.revisit-composition {
  position: relative;
  padding-bottom: 40px;/* Spacing-500 */
  padding-right: 16px; /* Spacing-200 */
}

.revisit-window {
  width: 100%;
  height: auto;
}

.revisit-card-wrap {
  position: absolute;
  right: 0;
  bottom: 0;
  width: 60%;
  z-index: 2;
  will-change: transform, opacity, filter;
}

.revisit-card-img {
  width: 100%;
  height: auto;
}

/* ==========================================================================
   3.4 读不动的时候 #features (Bento Grid + Nested Radius 24px - 16px = 8px)
   ========================================================================== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;           /* Spacing-300 */
}

.feature-card {
  background-color: var(--well);
  border: 1px solid var(--hairline);
  border-radius: 24px; /* rounded-3xl */
  padding: 16px;       /* Spacing-200 */
  display: flex;
  flex-direction: column;
  gap: 16px;           /* Spacing-200 */
  min-width: 0;
  transition:
    background-color 700ms var(--ease-fluid),
    transform 700ms var(--ease-fluid);
}

.feature-card:hover {
  background-color: var(--well-hover);
}

.feature-thumb {
  height: 208px;
  border-radius: 8px;  /* 24px - 16px = 8px (B3 Nested Radius Formula) */
  border: 1px solid var(--hairline);
  overflow: hidden;
  background-color: var(--paper);
  position: relative;
  transform: translateZ(0);
}

.feature-img {
  display: block;
  border-radius: 0;
}

.feature-img-bilingual {
  width: 100%;
  height: auto;
}

.feature-img-ja {
  width: 164.38%;
  max-width: none;
  height: auto;
  margin-left: -31.51%;
  margin-top: -5.48%;
}

.feature-img-popover,
.feature-img-quick,
.feature-img-note {
  width: min(100%, 360px);
  height: auto;
  margin-inline: auto;
}

/* Card 3: Live Audio Player Story Stage */
.feature-thumb-quote {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  padding: 24px 16px 16px; /* Spacing-300, Spacing-200 */
  text-align: center;
  background-color: var(--paper);
}

.feature-quote {
  margin: auto 0;
  font-family: var(--font-en-serif);
  font-size: 20px;     /* text-xl (B1) */
  line-height: 28px;
  font-weight: 400;
  color: var(--ink);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 4px;            /* Spacing-50 */
}

.tts-word {
  padding: 2px 4px;
  border-radius: 4px;
  transition:
    background-color 300ms var(--e2),
    color 300ms var(--e2);
}

.tts-word.is-speaking {
  background-color: var(--light-soft);
  color: var(--amber);
}

.tts-player-bar {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 8px;            /* Spacing-75 */
  padding: 8px 12px;   /* Spacing-75 × Spacing-100 */
  border-radius: 8px;
  background-color: var(--well);
}

.tts-equalizer {
  display: inline-flex;
  align-items: center;
  gap: 2px;            /* Spacing-25 */
  height: 12px;        /* Spacing-100 */
  flex-shrink: 0;
}

.tts-bar {
  width: 2px;
  height: 12px;
  border-radius: 9999px;
  background-color: var(--amber);
  transform: scaleY(0.35);
  transform-origin: center;
  will-change: transform;
}

.tts-progress-track {
  flex: 1;
  height: 4px;         /* Spacing-50 */
  border-radius: 9999px;
  background-color: var(--hairline);
  overflow: hidden;
  position: relative;
}

.tts-progress-fill {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: 9999px;
  background-color: var(--light);
  transform: scaleX(0.25);
  transform-origin: left center;
  will-change: transform;
}

.feature-quote-note {
  font-size: 12px;     /* text-xs (B1) */
  line-height: 16px;
  font-weight: 600;
  color: var(--ink-3);
  flex-shrink: 0;
}

.feature-body {
  padding: 0 8px 8px;  /* Spacing-75 */
}

.feature-title {
  margin: 0 0 8px;     /* Spacing-75 */
  font-size: 18px;     /* text-lg (B1) */
  line-height: 28px;
  font-weight: 600;
  color: var(--ink);
}

.feature-desc {
  margin: 0;
  font-size: 14px;     /* text-sm (B1) */
  line-height: 20px;
  color: var(--ink-2);
}

/* ==========================================================================
   3.5 没有打卡 #philosophy
   ========================================================================== */
.philosophy-header {
  max-width: 680px;    /* B5 */
  margin-bottom: 48px; /* Spacing-600 */
}

.philosophy-title {
  margin: 0 0 24px;    /* Spacing-300 */
  font-size: 48px;     /* text-5xl (B1) */
  line-height: 1.15;
  font-weight: 600;
  color: var(--ink);
}

.philosophy-body {
  max-width: 540px;
}

.philosophy-figure {
  margin: 0;
}

.stage-card-philosophy {
  max-width: 960px;
}

.philosophy-shot {
  width: 100%;
  height: auto;
}

.figure-caption {
  margin-top: 16px;    /* Spacing-200 */
  font-size: 12px;     /* text-xs (B1) */
  line-height: 16px;
  letter-spacing: 0.04em;
  color: var(--ink-3);
}

/* ==========================================================================
   3.6 你的书留在你的 Mac 上 (Full-bordered flat card, B4)
   ========================================================================== */
.privacy-card {
  max-width: 760px;
  margin-inline: auto;
  text-align: center;
  background-color: var(--well);
  border: 1px solid var(--hairline);
  border-radius: 24px; /* rounded-3xl */
  padding: 48px 32px;  /* Spacing-600 × Spacing-400 */
}

.privacy-card .section-title {
  margin-inline: auto;
  margin-bottom: 16px; /* Spacing-200 */
}

.privacy-body {
  margin-inline: auto;
}

/* ==========================================================================
   3.7 常见问题 #faq (B4: All-around borders on each card, no single-sided borders)
   ========================================================================== */
.faq-inner {
  max-width: 760px;
}

.faq-inner .section-header {
  margin-bottom: 32px; /* Spacing-400 */
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;           /* Spacing-100 */
}

.faq-item {
  background-color: var(--paper);
  border: 1px solid var(--hairline); /* 4-sided border per B4 */
  border-radius: 16px; /* rounded-2xl */
  padding: 0 24px;     /* Spacing-300 */
  transition:
    background-color 700ms var(--ease-fluid),
    border-color 700ms var(--ease-fluid);
}

.faq-item:hover {
  background-color: var(--well);
}

.faq-question {
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;           /* Spacing-200 */
  padding: 16px 0;     /* Spacing-200 */
  font-size: 16px;     /* text-base (B1) */
  line-height: 24px;
  font-weight: 600;
  color: var(--ink);
  cursor: pointer;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-question::after {
  content: "";
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  background:
    linear-gradient(var(--ink-2), var(--ink-2)) center / 14px 1.5px no-repeat,
    linear-gradient(var(--ink-2), var(--ink-2)) center / 1.5px 14px no-repeat;
  transition: transform 700ms var(--ease-fluid);
}

.faq-item[open] > .faq-question::after {
  transform: rotate(45deg);
}

.faq-answer {
  margin: 0;
  padding: 0 24px 16px 0; /* Spacing-300, Spacing-200 */
  font-size: 14px;     /* text-sm (B1) */
  line-height: 20px;
  color: var(--ink-2);
  max-width: 600px;
}

/* ==========================================================================
   3.8 最后一屏
   ========================================================================== */
main > .section-closing {
  padding-top: 64px;   /* Spacing-700 */
  padding-bottom: 96px;/* Spacing-900 */
}

.closing-card {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  background-color: var(--well);
  border: 1px solid var(--hairline);
  border-radius: 24px; /* rounded-3xl */
  padding: 64px 32px;  /* Spacing-700 × Spacing-400 */
}

.closing-wordmark {
  height: 40px;        /* Spacing-500 */
  width: auto;
  margin-bottom: 24px; /* Spacing-300 */
}

.closing-title {
  margin: 0 0 12px;    /* Spacing-100 */
  font-size: 48px;     /* text-5xl (B1) */
  line-height: 1.15;
  font-weight: 600;
  color: var(--ink);
}

.closing-subtitle {
  margin: 0 0 32px;    /* Spacing-400 */
  font-size: 16px;     /* text-base */
  line-height: 24px;
  color: var(--ink-2);
}

.closing-actions {
  display: flex;
  justify-content: center;
}

/* ==========================================================================
   3.9 页脚 (B4: All-around pill/card border instead of single-sided border-top)
   ========================================================================== */
.site-footer {
  padding: 0 0 48px;   /* Spacing-600 */
  font-size: 12px;     /* text-xs (B1) */
  line-height: 16px;
  letter-spacing: 0.04em;
  color: var(--ink-3);
}

.footer-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;           /* Spacing-200 */
  padding: 16px 24px;  /* Spacing-200 × Spacing-300 */
  border-radius: 16px; /* rounded-2xl */
  border: 1px solid var(--hairline);
  background-color: var(--paper);
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 16px;           /* Spacing-200 */
}

.footer-links[hidden] {
  display: none;
}

.footer-link {
  color: var(--ink-3);
  transition: color 400ms var(--ease-fluid);
}

.footer-link:hover {
  color: var(--ink);
}

/* ==========================================================================
   5. 演示视频遮罩
   ========================================================================== */
.video-modal {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 32px;       /* Spacing-400 */
}

.video-modal[hidden] {
  display: none;
}

.video-modal-backdrop {
  position: absolute;
  inset: 0;
  background-color: rgba(253, 252, 251, .94);
  -webkit-backdrop-filter: blur(24px);
  backdrop-filter: blur(24px);
}

.video-modal-dialog {
  position: relative;
  z-index: 1;
  width: min(1100px, 100%);
  background-color: var(--well);
  border: 1px solid var(--hairline);
  border-radius: 24px; /* rounded-3xl */
  padding: 16px;       /* Spacing-200 */
}

.video-modal-close {
  position: fixed;
  top: 24px;           /* Spacing-300 */
  right: 24px;         /* Spacing-300 */
  width: 40px;         /* Spacing-500 */
  height: 40px;
  border-radius: 9999px;
  border: 1px solid var(--hairline);
  background-color: var(--paper);
  color: var(--ink);
  cursor: pointer;
  padding: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition:
    background-color 700ms var(--ease-fluid),
    transform 700ms var(--ease-fluid);
}

.video-modal-close:hover {
  background-color: var(--well);
}

.video-modal-close:active {
  transform: scale(0.98);
}

.video-frame {
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: 8px;  /* 24px - 16px = 8px (B3 Nested Radius Formula) */
  overflow: hidden;
  border: 1px solid var(--hairline);
  box-shadow:
    0 32px 64px -32px rgba(80, 55, 20, .28),
    0 2px 8px rgba(0, 0, 0, .04);
  background-color: var(--paper);
}

.demo-video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ==========================================================================
   B7 & design-to-motion B2/B4/B6: Scroll Interpolation & Story Overlays
   ========================================================================== */

/* B7 Scroll interpolation: translate-y-16 (64px) + blur + opacity -> 0 over 850ms */
html.js-motion .reveal {
  opacity: 0;
  transform: translateY(48px);
  filter: blur(8px);
  transition:
    opacity 850ms var(--ease-fluid),
    transform 850ms var(--ease-fluid),
    filter 850ms var(--ease-fluid);
}

html.js-motion .reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
  filter: blur(0);
}

/* design-to-motion B2: Card rise choreography (24px, scale(0.985), blur(6px), 0.9s --e) */
html.js-motion .dtm-stage .hero-frame-card,
html.js-motion .dtm-stage .stage-card,
html.js-motion .dtm-bento-card {
  opacity: 0;
  transform: translateY(24px) scale(0.985);
  filter: blur(6px);
  transition:
    transform 900ms var(--e),
    opacity 650ms var(--e2),
    filter 750ms var(--e2);
  transition-delay: calc(var(--card-index, 0) * 80ms);
}

html.js-motion .dtm-stage.is-in .hero-frame-card,
html.js-motion .dtm-stage.is-in .stage-card,
html.js-motion .dtm-stage.is-in .dtm-bento-card {
  opacity: 1;
  transform: translateY(0) scale(1);
  filter: blur(0);
}

/* Floating cards inside compositions arrive 180ms after their parent surface (B2) */
html.js-motion .hero-card-unit,
html.js-motion .lookup-card-wrap,
html.js-motion .revisit-card-wrap {
  opacity: 0;
  transform: translateY(24px) scale(0.96);
  filter: blur(6px);
  transition:
    transform 1050ms var(--e) 180ms,
    opacity 750ms var(--e2) 180ms,
    filter 750ms var(--e2) 180ms;
}

html.js-motion .dtm-stage.is-in .hero-card-unit,
html.js-motion .dtm-stage.is-in .lookup-card-wrap,
html.js-motion .dtm-stage.is-in .revisit-card-wrap {
  opacity: 1;
  transform: translateY(0) scale(1);
  filter: blur(0);
}

/* ==========================================================================
   响应式：< 960px 单栏，图在文字下面
   ========================================================================== */
@media (max-width: 959px) {
  .container {
    width: min(1120px, calc(100% - 32px)); /* 16px × 2 */
  }

  main > .section {
    padding-block: 64px; /* Spacing-700 */
  }

  main > .section-hero {
    padding-top: 32px;   /* Spacing-400 */
    padding-bottom: 64px;/* Spacing-700 */
  }

  main > .section-lead {
    padding-block: 64px; /* Spacing-700 */
  }

  main > .section-closing {
    padding-top: 48px;   /* Spacing-600 */
    padding-bottom: 64px;/* Spacing-700 */
  }

  .island-header {
    top: 16px;           /* Spacing-200 */
  }

  .island-pill {
    width: 100%;
    max-width: 520px;
    justify-content: space-between;
    padding: 8px 8px 8px 16px;
  }

  .island-links {
    display: none;
  }

  .island-menu-btn {
    display: inline-flex;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    gap: 32px;           /* Spacing-400 */
  }

  .hero-title {
    font-size: 48px;     /* text-5xl (B1) */
    line-height: 1.12;
  }

  .hero-composition {
    padding-right: 8px;  /* Spacing-75 */
    padding-bottom: 32px;/* Spacing-400 */
  }

  .hero-card-unit {
    width: 55%;
  }

  .lead-en {
    font-size: 24px;     /* text-2xl (B1) */
    line-height: 32px;
  }

  .lead-zh {
    font-size: 20px;     /* text-xl (B1) */
    line-height: 28px;
  }

  .section-header {
    margin-bottom: 40px; /* Spacing-500 */
  }

  .section-title {
    font-size: 30px;     /* text-3xl (B1) */
    line-height: 36px;
  }

  .chapter-title {
    font-size: 24px;     /* text-2xl (B1) */
    line-height: 32px;
  }

  .philosophy-title,
  .closing-title {
    font-size: 36px;     /* text-4xl (B1) */
    line-height: 40px;
  }

  .journey-list {
    gap: 64px;           /* Spacing-700 */
  }

  .journey-item,
  .journey-item-reverse {
    grid-template-columns: 1fr;
    gap: 24px;           /* Spacing-300 */
  }

  .journey-item-reverse .journey-copy {
    order: 1;
  }

  .journey-item-reverse .journey-media {
    order: 2;
  }

  .lookup-card-wrap {
    width: min(320px, 68%);
    margin-top: -24px;   /* Spacing-300 */
  }

  /* 五 · 再遇见：手机只放 flip */
  .revisit-composition {
    padding: 0;
  }

  .revisit-window {
    display: none;
  }

  .revisit-card-wrap {
    position: relative;
    width: min(520px, 100%);
    margin-inline: auto;
  }

  .features-grid {
    grid-template-columns: 1fr;
    gap: 16px;           /* Spacing-200 */
  }

  .privacy-card,
  .closing-card {
    padding: 32px 24px;  /* Spacing-400 × Spacing-300 */
  }

  .footer-bar {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;           /* Spacing-100 */
  }

  .video-modal {
    padding: 16px;       /* Spacing-200 */
  }

  .video-modal-close {
    top: 16px;           /* Spacing-200 */
    right: 16px;         /* Spacing-200 */
  }
}

/* ==========================================================================
   prefers-reduced-motion: reduce (B7 & design-to-motion B8)
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  html.js-motion .reveal,
  html.js-motion .tagline-word,
  html.js-motion .dtm-stage .hero-frame-card,
  html.js-motion .dtm-stage .stage-card,
  html.js-motion .dtm-bento-card,
  html.js-motion .hero-card-unit,
  html.js-motion .lookup-card-wrap,
  html.js-motion .revisit-card-wrap {
    opacity: 1 !important;
    transform: none !important;
    filter: none !important;
    transition: none !important;
  }
}