:root {
  --ocean: #0f718d;
  --ocean-dk: #0b5065;
  --ocean-lt: #23a4c4;
  --leaf: #2d7d57;
  --leaf-lt: #54b978;
  --paper: #fffaf0;
  --sky: #e6f6fb;
  --sky-dk: #bee8f3;
  --accent: #f2aa3d;
  --accent-lt: #ffe08a;
  --white: #ffffff;
  --text: #1d3140;
  --text-lt: #5b7280;
  --card-bg: #f8fcff;
  --radius: 14px;
  --shadow: 0 4px 24px rgba(15, 113, 141, .13);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  background: var(--white);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
button, input { font: inherit; }

nav {
  position: fixed; top: 0; left: 0; width: 100%; z-index: 100;
  height: 60px; padding: 0 5%;
  display: flex; align-items: center; justify-content: space-between;
  background: rgba(11, 80, 101, .93);
  backdrop-filter: blur(10px);
}
.nav-logo { display: flex; align-items: center; gap: 10px; color: var(--white); font-size: 1rem; font-weight: 800; }
.nav-logo-img { height: 36px; width: auto; display: block; filter: brightness(0) invert(1); }
.logo-mark {
  width: 34px; height: 34px; border-radius: 10px;
  display: inline-flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--accent-lt), var(--accent));
  color: var(--ocean-dk); font-size: .86rem; letter-spacing: 0;
}
.nav-links { display: flex; align-items: center; gap: 24px; }
.nav-links a { color: rgba(255,255,255,.86); font-size: .88rem; transition: color .2s; }
.nav-links a:hover { color: var(--accent-lt); }
.nav-ai-btn {
  padding: 6px 12px; border-radius: 20px;
  background: rgba(255,255,255,.12); border: 1px solid rgba(255,255,255,.2);
}
.nav-hamburger {
  display: none; flex-direction: column; justify-content: center; gap: 5px;
  background: none; border: none; cursor: pointer; padding: 6px;
}
.nav-hamburger span {
  display: block; width: 22px; height: 2px; background: rgba(255,255,255,.9);
  border-radius: 2px; transition: transform .25s, opacity .25s;
}
.nav-hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-hamburger.open span:nth-child(2) { opacity: 0; }
.nav-hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

#hero {
  min-height: 100vh; position: relative; overflow: hidden;
  display: flex; align-items: center; justify-content: center;
  padding: 88px 5% 64px;
  background:
    radial-gradient(circle at 22% 25%, rgba(255, 224, 138, .28), transparent 26%),
    radial-gradient(circle at 76% 28%, rgba(84, 185, 120, .26), transparent 28%),
    linear-gradient(150deg, #0b5065 0%, #0f718d 42%, #23a4c4 72%, #2d7d57 100%);
}
#hero::before {
  content: ""; position: absolute; inset: 0; opacity: .34;
  background-image:
    linear-gradient(rgba(255,255,255,.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.08) 1px, transparent 1px);
  background-size: 52px 52px;
}
#hero::after {
  content: ""; position: absolute; inset: auto 0 0; height: 32%;
  background: linear-gradient(transparent, rgba(7, 49, 63, .34));
}
.hero-content {
  position: relative; z-index: 2;
  display: flex; align-items: center; gap: 68px;
  width: 100%; max-width: 1120px;
}
.book-scene { position: relative; width: 360px; height: 330px; flex: 0 0 360px; }
.book {
  position: absolute; width: 210px; min-height: 270px;
  padding: 24px 22px; border-radius: 12px 20px 20px 12px;
  background: var(--paper); color: var(--text);
  box-shadow: 0 22px 55px rgba(0,0,0,.25);
  display: flex; flex-direction: column; justify-content: space-between;
  border-left: 10px solid var(--accent);
}
.book::before {
  content: ""; position: absolute; inset: 0 18px 0 auto; width: 1px;
  background: rgba(11,80,101,.1);
}
.book span { font-size: .78rem; color: var(--ocean); font-weight: 800; letter-spacing: 1px; }
.book strong { font-size: 1.35rem; line-height: 1.25; color: var(--ocean-dk); }
.book em { font-size: .76rem; color: var(--text-lt); font-style: normal; }
.book-left { left: 8px; top: 38px; transform: rotate(-8deg); }
.book-right { right: 0; top: 18px; transform: rotate(7deg); border-left-color: var(--leaf-lt); }
.spark {
  position: absolute; width: 42px; height: 42px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  background: rgba(255,255,255,.18); color: var(--accent-lt);
  border: 1px solid rgba(255,255,255,.26); font-weight: 900;
  animation: float 5s ease-in-out infinite;
}
.s1 { left: 14px; top: 0; }
.s2 { right: 18px; bottom: 30px; animation-delay: -1.4s; }
.s3 { left: 130px; bottom: 0; animation-delay: -2.2s; }
@keyframes float { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-12px); } }
.hero-text { flex: 1; color: var(--white); }
.hero-tag {
  display: inline-block; margin-bottom: 16px; padding: 5px 15px;
  border-radius: 20px; background: rgba(255,255,255,.14);
  border: 1px solid rgba(255,255,255,.28);
  color: var(--accent-lt); font-size: .8rem; letter-spacing: 1px;
}
.hero-title { font-size: clamp(2.1rem, 4vw, 3.35rem); font-weight: 900; line-height: 1.18; margin-bottom: 14px; }
.hero-title span { color: var(--accent-lt); }
.hero-sub { font-size: 1.03rem; opacity: .88; margin-bottom: 28px; line-height: 1.85; }
.hero-cta {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 48px; padding: 0 28px; border-radius: 30px;
  background: var(--accent); color: var(--text); font-weight: 800;
  box-shadow: 0 4px 20px rgba(242,170,61,.42); transition: transform .2s, box-shadow .2s;
}
.hero-cta:hover { transform: translateY(-2px); box-shadow: 0 8px 28px rgba(242,170,61,.5); }
.promo-hero { min-height: 92vh; }
.promo-visual .book { min-height: 260px; }
.hero-actions { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.secondary-cta {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 48px; padding: 0 24px; border-radius: 30px;
  border: 1px solid rgba(255,255,255,.38);
  color: var(--white); font-weight: 800;
  background: rgba(255,255,255,.1);
}
.secondary-cta:hover { background: rgba(255,255,255,.18); }
.wave { display: block; width: 100%; overflow: hidden; line-height: 0; margin-bottom: -2px; }
.wave svg { display: block; }

#stats { background: var(--ocean-dk); padding: 28px 5%; }
.stats-grid {
  max-width: 920px; margin: 0 auto;
  display: flex; justify-content: space-around; flex-wrap: wrap; gap: 16px;
}
.stat-item { text-align: center; color: var(--white); min-width: 120px; }
.stat-num { display: block; color: var(--accent-lt); font-size: 2.2rem; font-weight: 900; line-height: 1; }
.stat-label { margin-top: 4px; font-size: .82rem; opacity: .75; }

section { padding: 72px 5%; }
.section-title { text-align: center; color: var(--ocean-dk); font-size: 1.9rem; font-weight: 900; margin-bottom: 8px; }
.section-sub { text-align: center; color: var(--text-lt); font-size: 1rem; margin-bottom: 48px; }
.section-sub em { color: var(--ocean); font-style: normal; font-weight: 800; }

.promo-section {
  background: var(--white);
  padding: 82px 5%;
}
.promo-section:nth-of-type(odd) { background: #f7fcff; }
.method-section {
  background: #f7fcff;
  padding-top: 72px;
}
.method-steps {
  max-width: 980px;
  margin: 0 auto 28px;
  display: flex;
  align-items: stretch;
}
.method-step {
  flex: 1;
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 14px;
  padding: 28px 26px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.method-step-num {
  font-size: 2.2rem;
  font-weight: 900;
  color: #c8dff5;
  line-height: 1;
}
.method-step h3 {
  font-size: 1rem;
  font-weight: 900;
  color: var(--ocean-dk);
  line-height: 1.35;
}
.method-step p {
  font-size: .87rem;
  color: var(--text-lt);
  line-height: 1.7;
  flex: 1;
  margin: 0;
}
.method-step-link {
  display: inline-block;
  margin-top: 4px;
  font-size: .8rem;
  font-weight: 900;
  color: var(--ocean);
  text-decoration: none;
  border: 1px solid var(--ocean);
  border-radius: 8px;
  padding: 6px 12px;
  align-self: flex-start;
  transition: background .15s;
}
.method-step-link:hover { background: #eaf4ff; }
.method-step-arrow {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  padding: 0 18px;
  font-size: 1.5rem;
  color: var(--ocean);
  font-weight: 900;
  padding-bottom: 60px; /* align with text area, above the link */
}
.method-outcome {
  max-width: 980px;
  margin: 0 auto;
  background: linear-gradient(120deg, #eaf4ff 0%, #e8f9ee 100%);
  border: 1px solid var(--sky-dk);
  border-radius: 14px;
  padding: 24px 32px;
  display: flex;
  align-items: center;
  gap: 28px;
}
.method-outcome strong {
  flex: 0 0 auto;
  font-size: 1.1rem;
  font-weight: 900;
  color: var(--ocean-dk);
  white-space: nowrap;
}
.method-outcome p {
  font-size: .88rem;
  color: var(--text-lt);
  line-height: 1.7;
  margin: 0;
}
.promo-head {
  max-width: 820px;
  margin: 0 auto 42px;
  text-align: center;
}
.promo-head p {
  color: var(--ocean);
  font-size: .82rem;
  font-weight: 900;
  letter-spacing: .08em;
  margin-bottom: 8px;
}
.promo-head h2 {
  color: var(--ocean-dk);
  font-size: clamp(1.7rem, 3vw, 2.45rem);
  line-height: 1.28;
  margin-bottom: 12px;
}
.promo-head span {
  display: block;
  color: var(--text-lt);
  font-size: 1rem;
  line-height: 1.8;
}
.language-map {
  max-width: 1120px;
  margin: 0 auto 26px;
  display: grid;
  gap: 14px;
}
.map-top {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) 42px minmax(0, .95fr);
  gap: 14px;
  align-items: stretch;
}
.map-step-label {
  width: max-content;
  max-width: 100%;
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--sky);
  color: var(--ocean-dk);
  font-size: .84rem;
  font-weight: 900;
}
.map-step-label.second {
  margin-top: 8px;
  background: #e8f6ee;
  color: #276c4c;
}
.source-text,
.language-points,
.reuse-text {
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 12px;
  padding: 20px;
  box-shadow: var(--shadow);
}
.source-text > span,
.language-points span,
.reuse-text > span {
  display: block;
  color: var(--ocean);
  font-size: .78rem;
  font-weight: 900;
  letter-spacing: .06em;
  margin-bottom: 10px;
}
.source-text p,
.reuse-text p {
  color: var(--text);
  font-size: 1rem;
  line-height: 1.85;
}
.key-word {
  padding: 1px 5px;
  border-radius: 6px;
  background: var(--accent-lt);
  color: #7a4c00;
  font-weight: 900;
}
.pattern-hit {
  text-decoration-line: underline;
  text-decoration-style: wavy;
  text-decoration-color: #d83b3b;
  text-decoration-thickness: 1.5px;
  text-underline-offset: 5px;
}
.reuse-text {
  border-left: 4px solid var(--leaf);
  max-width: 860px;
}
.language-points {
  display: grid;
  grid-template-columns: .9fr 1.1fr;
  gap: 18px;
  background: #fbfeff;
}
.language-points div {
  min-width: 0;
}
.language-points strong {
  display: inline-flex;
  max-width: 100%;
  margin: 0 0 8px;
  padding: 5px 9px;
  border-radius: 8px;
  background: var(--paper);
  color: #7a4c00;
  font-size: .88rem;
  font-weight: 900;
  line-height: 1.45;
  overflow-wrap: anywhere;
}
.language-points p {
  display: block;
  width: 100%;
  margin: 0 0 8px;
  padding: 8px 10px;
  border-radius: 8px;
  background: #e8f6ee;
  color: #276c4c;
  font-size: .9rem;
  font-weight: 900;
  line-height: 1.55;
  white-space: normal;
  overflow-wrap: anywhere;
}
.map-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ocean);
  font-size: 1.8rem;
  font-weight: 900;
}
.learning-note {
  max-width: 860px;
  padding: 18px 20px;
  border-radius: 12px;
  background: #fff7df;
  border: 1px solid #ffe0a3;
  color: #7a4c00;
  font-size: 1rem;
  line-height: 1.75;
  font-weight: 900;
}
.value-grid {
  max-width: 1120px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}
.value-card {
  min-height: 260px;
  padding: 24px;
  border: 1px solid var(--sky-dk);
  border-radius: 12px;
  background: var(--white);
  box-shadow: var(--shadow);
}
.value-card span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  margin-bottom: 18px;
  background: var(--sky);
  color: var(--ocean);
  font-weight: 900;
}
.value-card:nth-child(even) span {
  background: #e8f6ee;
  color: var(--leaf);
}
.value-card h3 {
  color: var(--ocean-dk);
  font-size: 1.08rem;
  line-height: 1.4;
  margin-bottom: 10px;
}
.value-card p {
  color: var(--text-lt);
  font-size: .92rem;
  line-height: 1.75;
}
.reader-promo-section {
  background: linear-gradient(180deg, #eef8f2 0%, #f7fcff 100%);
  padding: 82px 5%;
}
.reader-demo {
  max-width: 1060px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(280px, .75fr);
  gap: 22px;
  align-items: stretch;
}
.preview-legend {
  display: flex;
  gap: 14px;
  align-items: center;
  flex-wrap: wrap;
  padding-top: 10px;
  border-top: 1px solid var(--sky-dk);
}
.legend-word, .legend-pattern {
  font-size: .78rem;
  color: var(--text-lt);
  display: flex;
  align-items: center;
  gap: 6px;
}
.legend-word mark, .legend-pattern span {
  font-size: .78rem;
}
.reader-panel {
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 14px;
  padding: 26px;
  box-shadow: var(--shadow);
}
.reader-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 18px;
  margin-bottom: 22px;
  border-bottom: 1px solid var(--sky-dk);
}
.reader-toolbar button {
  border: 0;
  border-radius: 999px;
  background: var(--leaf);
  color: var(--white);
  padding: 9px 16px;
  font-weight: 900;
}
.reader-toolbar span {
  color: var(--text-lt);
  font-size: .84rem;
  font-weight: 800;
}
.reader-panel p {
  color: var(--text);
  font-size: clamp(1.18rem, 2vw, 1.55rem);
  line-height: 2.1;
}
.demo-sentence {
  cursor: pointer;
  border-radius: 8px;
  padding: 3px 6px;
  border: 1px solid transparent;
}
.demo-sentence:hover,
.demo-sentence.active {
  background: #f3f8ff;
  border-color: #9ec5ff;
}
.demo-word {
  display: inline;
  border-radius: 7px;
  padding: 0 2px;
  transition: color .12s ease, background .12s ease, transform .12s ease;
}
.demo-word.spoken {
  color: var(--leaf);
}
.demo-word.active {
  display: inline-block;
  color: #17212b;
  background: var(--accent-lt);
  border-radius: 7px;
  padding: 0 5px;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(183, 121, 31, .18);
}
.benefit-list {
  display: grid;
  gap: 14px;
}
.benefit-list div {
  background: var(--white);
  border: 1px solid rgba(190,232,243,.85);
  border-radius: 12px;
  padding: 20px;
  box-shadow: 0 4px 18px rgba(15, 113, 141, .08);
}
.benefit-list strong {
  display: block;
  color: var(--ocean-dk);
  font-size: 1rem;
  margin-bottom: 8px;
}
.benefit-list p {
  color: var(--text-lt);
  font-size: .9rem;
  line-height: 1.7;
}
/* ── Reader section sub-head ── */
.promo-sub-head {
  max-width: 760px;
  margin: 52px auto 28px;
  text-align: center;
}
.promo-sub-head p {
  font-size: .78rem;
  font-weight: 900;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--ocean);
  margin-bottom: 6px;
}
.promo-sub-head h3 {
  font-size: clamp(1.25rem, 2.5vw, 1.65rem);
  font-weight: 900;
  color: var(--text);
  margin-bottom: 10px;
  line-height: 1.3;
}
.promo-sub-head span {
  font-size: .9rem;
  color: var(--text-lt);
  line-height: 1.6;
}

/* ── Chat demo panel ── */
.dialog-chat-demo { align-items: stretch; }
.chat-demo-panel {
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 14px;
  overflow: hidden;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
}
.chat-demo-bar {
  padding: 12px 16px;
  background: #f0f8ff;
  border-bottom: 1px solid var(--sky-dk);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.chat-demo-roles { display: flex; gap: 8px; flex-wrap: wrap; }
.role-tag {
  padding: 3px 10px;
  border-radius: 999px;
  font-size: .72rem;
  font-weight: 900;
}
.role-a { background: #e0f0ff; color: #1a5fa0; }
.role-b { background: #e6f9ee; color: #1a6640; }
.chat-demo-play-btn {
  padding: 5px 14px;
  border-radius: 8px;
  border: none;
  background: var(--ocean);
  color: var(--white);
  font-size: .8rem;
  font-weight: 900;
  cursor: pointer;
}
.chat-demo-scene {
  padding: 8px 16px;
  font-size: .78rem;
  color: var(--text-lt);
  background: #fafcff;
  border-bottom: 1px solid var(--sky-dk);
  font-style: italic;
}
.chat-demo-window {
  flex: 1;
  padding: 14px;
  background: #ece5dd;
  display: flex;
  flex-direction: column;
  gap: 10px;
  overflow-y: auto;
}
.chat-demo-bubble {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  max-width: 85%;
}
.cdemo-left { align-self: flex-start; }
.cdemo-right { align-self: flex-end; flex-direction: row-reverse; }
.cdemo-avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  flex: 0 0 34px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .65rem;
  font-weight: 900;
}
.cdemo-av-a { background: #d0e8ff; color: #1a5fa0; }
.cdemo-av-b { background: #c8f0d8; color: #1a6640; }
.cdemo-content { display: flex; flex-direction: column; gap: 2px; }
.cdemo-name { font-size: .7rem; font-weight: 900; color: var(--text-lt); padding: 0 4px; }
.cdemo-right .cdemo-name { text-align: right; }
.cdemo-text {
  background: var(--white);
  border-radius: 0 10px 10px 10px;
  padding: 8px 12px;
  font-size: .88rem;
  color: var(--text);
  line-height: 1.5;
  box-shadow: 0 1px 2px rgba(0,0,0,.08);
}
.cdemo-right .cdemo-text {
  background: #dcf8c6;
  border-radius: 10px 0 10px 10px;
}
.chat-demo-bubble { transition: opacity .15s; }
.chat-demo-bubble:hover { opacity: .85; }
.chat-demo-bubble.cdemo-playing .cdemo-text { outline: 2px solid var(--ocean); outline-offset: 2px; }
.cdemo-text em {
  display: block;
  font-style: normal;
  font-size: .75rem;
  color: var(--text-lt);
  margin-top: 3px;
}

/* ── Dialog promo section ── */
.dialog-promo-section { background: #f7fbff; }

/* 1. Chain relationship */
.dialog-chain {
  max-width: 900px;
  margin: 0 auto 52px;
  display: flex;
  align-items: stretch;
  gap: 0;
}
.chain-step {
  flex: 1;
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 14px;
  padding: 24px 22px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}
.chain-highlight {
  background: #eaf4ff;
  border-color: var(--ocean);
}
.chain-icon { font-size: 1.6rem; line-height: 1; }
.chain-step strong { font-size: 1rem; color: var(--ocean-dk); }
.chain-highlight strong { color: var(--ocean); }
.chain-step p { font-size: .82rem; color: var(--text-lt); line-height: 1.55; margin: 0; }
.chain-arrow {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  padding: 0 12px;
  font-size: 1.4rem;
  color: var(--ocean);
  font-weight: 900;
}

/* 2. Three dialogs grid */
.dialog-trio {
  max-width: 1060px;
  margin: 0 auto 48px;
}
.language-map .dialog-trio {
  max-width: none;
  margin-bottom: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}
.dialog-trio-card {
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 14px;
  overflow: hidden;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
}
.trio-header {
  padding: 12px 16px;
  background: #f0f8ff;
  border-bottom: 1px solid var(--sky-dk);
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}
.trio-badge {
  padding: 3px 9px;
  border-radius: 999px;
  background: var(--ocean);
  color: var(--white);
  font-size: .72rem;
  font-weight: 900;
  white-space: nowrap;
}
.trio-scene { font-size: .8rem; color: var(--text-lt); }
.trio-body { padding: 12px 16px; display: flex; flex-direction: column; gap: 10px; flex: 1; }
.trio-turn {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  max-width: 88%;
  align-self: flex-start;
}
.trio-right {
  flex-direction: row-reverse;
  align-self: flex-end;
}
.trio-name {
  flex: 0 0 auto;
  font-size: .72rem;
  font-weight: 900;
  color: var(--ocean);
  padding-top: 4px;
  min-width: 34px;
}
.trio-right .trio-name { color: var(--leaf); text-align: right; }
.trio-turn > div {
  flex: 1;
  min-width: 0;
  background: #f0f4ff;
  border-radius: 0 12px 12px 12px;
  padding: 8px 12px;
}
.trio-right > div {
  background: #edfaf3;
  border-radius: 12px 0 12px 12px;
}
.trio-turn p {
  font-size: .86rem;
  color: var(--text);
  line-height: 1.55;
  margin: 0;
}
.trio-turn em {
  display: block;
  font-style: normal;
  font-size: .76rem;
  color: var(--text-lt);
  margin-top: 4px;
}

/* 3. Direct experience CTA */
.dialog-experience {
  max-width: 820px;
  margin: 0 auto;
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 16px;
  padding: 28px 36px;
  display: flex;
  align-items: center;
  gap: 32px;
  box-shadow: var(--shadow);
}
.dialog-exp-text { flex: 1; }
.dialog-exp-text strong { display: block; font-size: 1.05rem; color: var(--ocean-dk); margin-bottom: 6px; }
.dialog-exp-text p { font-size: .88rem; color: var(--text-lt); margin: 0; line-height: 1.6; }
.dialog-exp-btn {
  flex: 0 0 auto;
  padding: 12px 24px;
  border-radius: 10px;
  background: var(--ocean);
  color: var(--white);
  font-weight: 900;
  font-size: .92rem;
  text-decoration: none;
  white-space: nowrap;
  transition: background .15s;
}
.dialog-exp-btn:hover { background: var(--ocean-dk); }
.versions-section { background: var(--white); }
.stats-bar {
  max-width: 900px;
  margin: 0 auto 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--card-bg);
  border: 1px solid var(--sky-dk);
  border-radius: 16px;
  padding: 28px 32px;
  gap: 0;
  flex-wrap: wrap;
}
.stat-item {
  flex: 1;
  min-width: 120px;
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.stat-item strong {
  font-size: clamp(1.8rem, 3.5vw, 2.6rem);
  font-weight: 900;
  color: var(--ocean-dk);
  line-height: 1;
}
.stat-item strong em {
  font-style: normal;
  font-size: 60%;
  color: var(--ocean);
}
.stat-item span {
  font-size: .82rem;
  color: var(--text-lt);
  font-weight: 600;
}
.stat-divider {
  width: 1px;
  height: 48px;
  background: var(--sky-dk);
  flex: 0 0 1px;
  margin: 0 8px;
}
.version-grid {
  max-width: 960px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}
.version-grid span {
  min-height: 58px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  background: var(--card-bg);
  border: 1px solid var(--sky-dk);
  color: var(--ocean-dk);
  font-weight: 900;
}
.version-grid span:nth-child(4n + 2),
.version-grid span:nth-child(4n + 3) {
  background: #f0faf4;
  border-color: #cbeed8;
  color: #276c4c;
}
.final-cta {
  padding: 72px 5%;
  text-align: center;
  color: var(--white);
  background: linear-gradient(135deg, var(--ocean-dk), var(--ocean), var(--leaf));
}
.final-cta h2 {
  max-width: 760px;
  margin: 0 auto 10px;
  font-size: clamp(1.55rem, 3vw, 2.3rem);
  line-height: 1.3;
}
.final-cta p {
  max-width: 680px;
  margin: 0 auto 24px;
  color: rgba(255,255,255,.82);
}
.final-cta a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 24px;
  border-radius: 999px;
  background: var(--accent);
  color: var(--text);
  font-weight: 900;
}

#why, #demo { background: var(--sky); }
.why-grid, .products-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 28px;
  max-width: 1000px; margin: 0 auto;
}
.why-col, .product-card, .reader-card, .companion-card {
  background: var(--white); border-radius: var(--radius); box-shadow: var(--shadow); overflow: hidden;
}
.why-col-header { padding: 28px 28px 24px; color: var(--white); text-align: center; }
.why-col-header.blue { background: linear-gradient(135deg, var(--ocean), var(--ocean-lt)); }
.why-col-header.green { background: linear-gradient(135deg, var(--leaf), var(--leaf-lt)); }
.why-col-icon { font-size: 2.3rem; margin-bottom: 8px; }
.why-col-title { font-size: 1.3rem; font-weight: 900; }
.why-col-sub { font-size: .85rem; opacity: .86; }
.why-items { padding: 22px 24px; display: flex; flex-direction: column; gap: 18px; }
.why-item { display: flex; align-items: flex-start; gap: 14px; }
.why-item-icon {
  flex: 0 0 32px; width: 32px; height: 32px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  background: var(--sky); color: var(--ocean); font-size: .72rem; font-weight: 900;
}
.why-col:last-child .why-item-icon { background: #e8f6ee; color: var(--leaf); }
.why-item-title { font-size: .95rem; font-weight: 800; color: var(--ocean-dk); margin-bottom: 4px; }
.why-col:last-child .why-item-title { color: var(--leaf); }
.why-item-desc { font-size: .84rem; color: var(--text-lt); line-height: 1.65; }

#system { background: var(--white); }
.product-highlights {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px;
  max-width: 920px; margin: 0 auto 52px;
}
.ph-item {
  text-align: center; background: var(--card-bg);
  border-radius: var(--radius); padding: 28px 16px;
  box-shadow: var(--shadow); border-top: 3px solid var(--ocean);
  transition: transform .2s;
}
.ph-item:nth-child(even) { border-top-color: var(--leaf); }
.ph-item:hover { transform: translateY(-3px); }
.ph-num { font-size: 2.4rem; font-weight: 900; color: var(--ocean); line-height: 1; margin-bottom: 6px; }
.ph-item:nth-child(even) .ph-num { color: var(--leaf); }
.ph-label { font-size: 1rem; font-weight: 800; margin-bottom: 8px; }
.ph-sub { font-size: .78rem; color: var(--text-lt); line-height: 1.5; }
.product-card { transition: transform .25s; }
.product-card:hover { transform: translateY(-4px); }
.card-header { padding: 28px 28px 20px; background: linear-gradient(135deg, var(--ocean), var(--ocean-lt)); color: var(--white); }
.card-header.green { background: linear-gradient(135deg, var(--leaf), var(--leaf-lt)); }
.card-level { font-size: .78rem; opacity: .8; letter-spacing: 1px; margin-bottom: 6px; }
.card-title { font-size: 1.45rem; font-weight: 900; }
.card-body { padding: 24px 28px; }
.card-stats { display: flex; gap: 22px; margin-bottom: 16px; flex-wrap: wrap; }
.cstat { text-align: center; }
.cstat-n { display: block; color: var(--ocean); font-size: 1.45rem; font-weight: 900; }
.card-header.green ~ .card-body .cstat-n { color: var(--leaf); }
.cstat-l { font-size: .75rem; color: var(--text-lt); }
.card-books { display: flex; flex-wrap: wrap; gap: 8px; }
.book-tag {
  background: var(--sky); color: var(--ocean-dk);
  padding: 4px 10px; border-radius: 6px; font-size: .78rem; font-weight: 700;
}
.card-header.green ~ .card-body .book-tag { background: #e8f6ee; color: var(--leaf); }

.reader-layout {
  display: grid; grid-template-columns: 285px 1fr; gap: 28px;
  max-width: 1000px; margin: 0 auto;
}
.story-list { display: flex; flex-direction: column; gap: 10px; }
.story-btn {
  background: var(--white); border: 2px solid transparent; border-radius: var(--radius);
  padding: 15px 16px; cursor: pointer; text-align: left;
  box-shadow: 0 2px 8px rgba(0,0,0,.06); transition: all .2s;
}
.story-btn:hover { border-color: var(--ocean-lt); }
.story-btn.active { border-color: var(--ocean); background: #f2fbfe; }
.story-level { color: var(--ocean); font-size: .7rem; font-weight: 800; letter-spacing: .5px; margin-bottom: 4px; }
.story-title { font-size: .9rem; font-weight: 800; line-height: 1.4; }
.reader-card { padding: 28px; }
.reader-meta { display: flex; justify-content: space-between; gap: 12px; color: var(--ocean); font-size: .78rem; font-weight: 800; margin-bottom: 10px; }
.reader-card h3 { color: var(--ocean-dk); font-size: 1.45rem; line-height: 1.35; margin-bottom: 8px; }
.reader-intro { color: var(--text-lt); font-size: .9rem; margin-bottom: 20px; }
.reader-body { display: flex; flex-direction: column; gap: 14px; }
.reader-body p { font-size: .95rem; color: var(--text); line-height: 1.82; }
.word-bank {
  margin-top: 24px; padding-top: 18px; border-top: 1px solid var(--sky-dk);
}
.word-bank-title { color: var(--ocean-dk); font-size: .86rem; font-weight: 900; margin-bottom: 10px; }
.word-tags { display: flex; flex-wrap: wrap; gap: 8px; }
.word-tag {
  background: var(--paper); color: #7a4c00; border: 1px solid #ffe2a6;
  padding: 5px 10px; border-radius: 6px; font-size: .8rem; font-weight: 800;
}

#practice { background: var(--white); }
.quiz-wrap { max-width: 740px; margin: 0 auto; }
.quiz-topic { text-align: center; color: var(--ocean); font-size: .88rem; font-weight: 800; letter-spacing: .5px; margin-bottom: 24px; }
.quiz-q {
  background: var(--card-bg); border-radius: var(--radius); padding: 22px 24px;
  margin-bottom: 16px; box-shadow: 0 2px 10px rgba(0,0,0,.06);
}
.q-label { color: var(--text-lt); font-size: .72rem; font-weight: 800; margin-bottom: 8px; }
.q-text { color: var(--text); font-size: .95rem; font-weight: 800; margin-bottom: 14px; }
.q-options { display: flex; flex-direction: column; gap: 8px; }
.opt-btn {
  display: flex; gap: 10px; align-items: center; width: 100%;
  background: var(--sky); border: 2px solid transparent; border-radius: 8px;
  padding: 10px 14px; cursor: pointer; text-align: left; font-size: .88rem;
  transition: all .18s;
}
.opt-btn:hover:not(:disabled) { border-color: var(--ocean-lt); background: #d8f0f7; }
.opt-btn.selected { border-color: var(--ocean); background: #c9eaf3; }
.opt-btn.correct { border-color: var(--leaf); background: #d9f2e3; color: var(--leaf); font-weight: 800; }
.opt-btn.wrong { border-color: #d9534f; background: #fde8e8; color: #b93434; }
.opt-btn:disabled { cursor: default; }
.opt-key { color: var(--ocean); font-weight: 900; flex: 0 0 18px; }
.q-explanation {
  display: none; margin-top: 12px; padding: 10px 14px;
  background: #fff7df; border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0; color: var(--text-lt); font-size: .84rem; line-height: 1.6;
}
.q-explanation.show { display: block; }
.quiz-submit-row { text-align: center; margin-top: 8px; }
.btn-submit {
  min-height: 48px; padding: 0 36px; border: none; border-radius: 30px;
  background: var(--ocean); color: var(--white); cursor: pointer;
  font-size: 1rem; font-weight: 800; transition: background .2s, transform .15s;
}
.btn-submit:hover:not(:disabled) { background: var(--ocean-dk); transform: translateY(-2px); }
.btn-submit:disabled { background: #9eaeb6; cursor: default; }
.quiz-result {
  display: none; text-align: center; margin-top: 20px; background: var(--card-bg);
  border-radius: var(--radius); padding: 24px; box-shadow: var(--shadow);
}
.quiz-result.show { display: block; }
.result-score { color: var(--ocean); font-size: 2.4rem; font-weight: 900; }
.result-msg { color: var(--text-lt); margin-top: 8px; font-size: .95rem; }

#companion { background: linear-gradient(160deg, #f3fbfd 0%, #eef8f2 100%); }
.companion-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px;
  max-width: 1000px; margin: 0 auto;
}
.companion-card { padding: 24px; border-top: 3px solid var(--ocean); }
.companion-card:nth-child(even) { border-top-color: var(--leaf); }
.companion-card span { color: var(--accent); font-size: 1.8rem; font-weight: 900; line-height: 1; }
.companion-card strong { display: block; margin: 10px 0 8px; color: var(--ocean-dk); font-size: 1.05rem; }
.companion-card p { color: var(--text-lt); font-size: .86rem; line-height: 1.7; }

footer { background: var(--ocean-dk); color: var(--white); text-align: center; padding: 34px 5%; }
.footer-brand { font-weight: 900; margin-bottom: 4px; }
.footer-sub { font-size: .78rem; opacity: .68; }
.footer-copy { font-size: .75rem; opacity: .5; margin-top: 10px; }

.browser-shell { background: linear-gradient(180deg, var(--sky) 0%, #f7fcff 36%, #fff 100%); }
.browser-section { padding: 72px 5%; }
.section-head {
  max-width: 1280px; margin: 0 auto 28px;
  display: flex; align-items: flex-start; justify-content: space-between; gap: 20px;
}
.section-head .section-title, .section-head .section-sub { text-align: left; margin-left: 0; }
.section-head .section-sub { margin-bottom: 0; }
.status-pill {
  flex-shrink: 0; border-radius: 999px; padding: 7px 14px;
  background: var(--white); color: var(--ocean-dk);
  border: 1px solid var(--sky-dk); font-size: .82rem; font-weight: 800;
  box-shadow: 0 2px 10px rgba(15,113,141,.08);
}
.status-pill[data-kind="loading"] { color: #966200; background: #fff7df; border-color: #ffe0a3; }
.status-pill[data-kind="ok"] { color: var(--leaf); background: #eef9f2; border-color: #cbeed8; }
.status-pill[data-kind="error"] { color: #b93434; background: #fff0f0; border-color: #ffd0d0; }

.workspace-grid {
  max-width: 1280px; margin: 0 auto;
  display: grid; grid-template-columns: 310px 310px minmax(0, 1fr); gap: 18px;
  align-items: start;
}
.control-panel, .chapter-panel, .article-panel {
  background: var(--white); border-radius: var(--radius);
  box-shadow: var(--shadow); border: 1px solid rgba(190,232,243,.72);
}
.control-panel, .chapter-panel { padding: 18px; position: sticky; top: 76px; max-height: calc(100vh - 96px); overflow: auto; }
.article-panel { min-height: 520px; overflow: hidden; }
.panel-title, .block-title {
  color: var(--ocean-dk); font-size: .9rem; font-weight: 900;
  letter-spacing: .5px; margin-bottom: 14px;
}
.filters { display: grid; gap: 12px; margin-bottom: 14px; }
.filters label { display: grid; gap: 5px; }
.filters span { color: var(--text-lt); font-size: .76rem; font-weight: 800; }
.filters select, .filters input {
  width: 100%; height: 38px; border: 1.5px solid var(--sky-dk);
  border-radius: 8px; padding: 0 10px; outline: none; color: var(--text);
  background: #fbfeff;
}
.filters select:focus, .filters input:focus { border-color: var(--ocean-lt); }
.primary-btn {
  width: 100%; height: 42px; border: none; border-radius: 999px;
  background: var(--ocean); color: var(--white); font-weight: 900; cursor: pointer;
  transition: background .2s, transform .15s;
}
.primary-btn:hover { background: var(--ocean-dk); transform: translateY(-1px); }
.book-list, .chapter-tree { display: grid; gap: 10px; margin-top: 16px; }
.list-note {
  color: var(--text-lt); font-size: .76rem; font-weight: 700;
  padding: 8px 10px; background: var(--card-bg); border-radius: 8px;
}
.book-item, .chapter-item, .extend-item {
  width: 100%; border: 2px solid transparent; border-radius: 10px;
  background: var(--card-bg); cursor: pointer; text-align: left;
  transition: border-color .18s, background .18s, transform .18s;
}
.book-item {
  display: grid; grid-template-columns: 54px 1fr; gap: 12px; padding: 10px;
}
.book-item:hover, .chapter-item:hover, .extend-item:hover { border-color: var(--ocean-lt); background: #f1fbfe; }
.book-item.active, .chapter-item.active { border-color: var(--ocean); background: var(--sky); }
.book-cover {
  width: 54px; aspect-ratio: 3 / 4; border-radius: 7px;
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--ocean), var(--leaf));
  color: var(--white); font-size: .76rem; font-weight: 900; overflow: hidden;
}
.book-cover img { width: 100%; height: 100%; object-fit: cover; display: block; }
.book-info { min-width: 0; display: grid; gap: 3px; }
.book-info strong {
  color: var(--text); font-size: .86rem; line-height: 1.35;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.book-info em, .book-info small { color: var(--text-lt); font-style: normal; font-size: .72rem; line-height: 1.35; }
.selected-book {
  display: grid; gap: 4px; padding: 12px; margin-bottom: 12px;
  border-radius: 10px; background: linear-gradient(135deg, #f4fcff, #eef9f2);
}
.selected-book strong { color: var(--ocean-dk); font-size: .9rem; line-height: 1.35; }
.selected-book span { color: var(--text-lt); font-size: .76rem; }
.chapter-item {
  display: grid; gap: 3px; padding: 10px 10px 10px calc(10px + var(--depth) * 13px);
}
.chapter-item.article-dir { border-left: 4px solid var(--leaf-lt); }
.chapter-name { color: var(--text); font-size: .85rem; font-weight: 850; line-height: 1.35; }
.chapter-meta { color: var(--text-lt); font-size: .72rem; }

.empty-state {
  min-height: 520px; display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 8px; padding: 36px; text-align: center; color: var(--text-lt);
}
.empty-state strong { color: var(--ocean-dk); font-size: 1.1rem; }
.empty-state span { max-width: 420px; font-size: .88rem; }
.hidden { display: none !important; }
.article-content { padding: 24px; }
.article-header {
  display: flex; align-items: flex-start; justify-content: space-between; gap: 16px;
  padding-bottom: 18px; border-bottom: 1px solid var(--sky-dk); margin-bottom: 20px;
}
.article-kicker { color: var(--ocean); font-size: .78rem; font-weight: 900; margin-bottom: 5px; }
.article-header h2 { color: var(--ocean-dk); font-size: 1.55rem; line-height: 1.28; }
.article-badges { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 7px; }
.article-badges span {
  padding: 4px 9px; border-radius: 999px; background: var(--sky);
  color: var(--ocean-dk); font-size: .74rem; font-weight: 850;
}
.content-grid { display: grid; grid-template-columns: minmax(0, 1.1fr) 330px; gap: 18px; align-items: start; }
.lesson-card, .resource-card, .questions-card, .extend-card {
  background: var(--card-bg); border: 1px solid var(--sky-dk);
  border-radius: 12px; padding: 18px;
}
.lesson-body { display: grid; gap: 12px; }
.lesson-body p {
  background: var(--white); border-radius: 8px; padding: 12px 14px;
  color: var(--text); font-size: .96rem; line-height: 1.82;
}
.resource-stack { display: grid; gap: 18px; }
.word-list, .sentence-list, .question-list, .extend-list { display: grid; gap: 10px; }
.word-row, .sentence-row, .question-row {
  background: var(--white); border-radius: 9px; padding: 11px 12px;
  border: 1px solid rgba(190,232,243,.65);
}
.word-row { display: grid; grid-template-columns: 110px 1fr; gap: 10px; align-items: start; }
.word-row strong { color: var(--ocean-dk); font-size: .9rem; overflow-wrap: anywhere; }
.word-row span, .sentence-row span, .question-row span {
  color: var(--text-lt); font-size: .82rem; line-height: 1.6;
}
.sentence-row strong { display: block; color: var(--text); font-size: .88rem; line-height: 1.55; margin-bottom: 5px; }
.questions-card, .extend-card { margin-top: 18px; }
.question-row { display: grid; grid-template-columns: 28px 1fr; gap: 10px; }
.q-index {
  width: 28px; height: 28px; border-radius: 50%; background: var(--ocean);
  color: var(--white); display: flex; align-items: center; justify-content: center;
  font-size: .76rem; font-weight: 900;
}
.question-row strong { display: block; color: var(--text); font-size: .9rem; line-height: 1.55; }
.question-row em { display: block; color: var(--leaf); font-style: normal; font-size: .83rem; font-weight: 800; margin-top: 5px; }
.extend-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.extend-item {
  display: grid; grid-template-columns: 70px 1fr; gap: 12px; padding: 12px;
  border-color: rgba(190,232,243,.8);
}
.extend-item img, .extend-thumb {
  width: 70px; height: 58px; border-radius: 8px; object-fit: cover;
  background: linear-gradient(135deg, var(--ocean), var(--leaf));
  color: var(--white); display: flex; align-items: center; justify-content: center;
  font-size: .72rem; font-weight: 900;
}
.extend-item strong {
  display: block; color: var(--text); font-size: .86rem; line-height: 1.4; margin-bottom: 4px;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.extend-item span, .extend-item small { display: block; color: var(--text-lt); font-size: .76rem; line-height: 1.45; }
.extend-detail {
  grid-column: 1 / -1; background: var(--white); border: 1px solid var(--sky-dk);
  border-left: 4px solid var(--leaf); border-radius: 10px; padding: 14px;
}
.extend-detail > strong { color: var(--ocean-dk); display: block; margin-bottom: 5px; }
.extend-detail p { color: var(--text-lt); font-size: .84rem; margin-bottom: 12px; }
.detail-cols { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.detail-cols em { display: block; color: var(--ocean); font-style: normal; font-size: .78rem; font-weight: 900; margin-bottom: 6px; }
.detail-cols ul { list-style: none; display: grid; gap: 7px; }
.detail-cols li { color: var(--text); font-size: .82rem; line-height: 1.55; background: var(--card-bg); border-radius: 8px; padding: 8px; }
.detail-cols li span { display: block; color: var(--text-lt); margin-top: 3px; }
.dialog-item {
  background: var(--white);
  border: 1px solid var(--sky-dk);
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 12px;
}
.dialog-item-head {
  display: grid;
  gap: 3px;
  padding: 10px 13px;
  background: #f4fbff;
  border-bottom: 1px solid var(--sky-dk);
}
.dialog-item-head strong { color: var(--ocean-dk); font-size: .88rem; }
.dialog-item-head span { color: var(--text-lt); font-size: .78rem; }
.dialog-item-body { display: grid; }
.dialog-turn-row {
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 10px;
  padding: 9px 13px;
  border-bottom: 1px solid var(--sky-dk);
  align-items: start;
}
.dialog-turn-row:last-child { border-bottom: none; }
.dialog-turn-row.turn-a { background: var(--white); }
.dialog-turn-row.turn-b { background: #f7fbff; }
.dialog-turn-row > strong { color: var(--ocean); font-size: .78rem; padding-top: 2px; }
.dialog-turn-row.turn-b > strong { color: var(--leaf); }
.dialog-turn-row > div > p { color: var(--text); font-size: .88rem; line-height: 1.55; }
.dialog-turn-row > div > span { color: var(--text-lt); font-size: .78rem; }
.mini-state {
  color: var(--text-lt); font-size: .84rem; line-height: 1.55;
  padding: 12px; border-radius: 8px; background: rgba(255,255,255,.76);
}
.mini-state.error { color: #b93434; background: #fff0f0; }

.fade-in { opacity: 0; transform: translateY(24px); transition: opacity .6s ease, transform .6s ease; }
.fade-in.visible { opacity: 1; transform: translateY(0); }

@media (max-width: 900px) {
  .hero-content { flex-direction: column; gap: 34px; text-align: center; }
  .book-scene { width: min(360px, 92vw); flex-basis: 310px; transform: scale(.92); }
  .why-grid, .products-grid, .reader-layout, .companion-grid { grid-template-columns: 1fr; }
  .map-top { grid-template-columns: 1fr; }
  .map-arrow { transform: rotate(90deg); min-height: 24px; }
  .value-grid, .reader-demo { grid-template-columns: 1fr; }
  .method-steps { flex-direction: column; }
  .method-step-arrow { transform: rotate(90deg); align-self: center; padding: 0; }
  .method-outcome { flex-direction: column; gap: 12px; text-align: center; }
  .dialog-trio { grid-template-columns: 1fr; }
  .stats-bar { gap: 16px; padding: 20px; }
  .stat-divider { display: none; }
  .dialog-chain { flex-direction: column; gap: 12px; }
  .chain-arrow { transform: rotate(90deg); align-self: center; padding: 4px 0; }
  .dialog-experience { flex-direction: column; gap: 18px; text-align: center; padding: 24px 20px; }
  .dialog-exp-btn { width: 100%; text-align: center; }
  .version-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .product-highlights { grid-template-columns: repeat(2, 1fr); }
  .workspace-grid { grid-template-columns: 1fr; }
  .control-panel, .chapter-panel { position: static; max-height: none; }
  .content-grid, .extend-list, .detail-cols { grid-template-columns: 1fr; }
  .section-head { flex-direction: column; }
  .article-header { flex-direction: column; }
  .article-badges { justify-content: flex-start; }
}

@media (max-width: 768px) {
  nav { height: 56px; }
  .nav-hamburger { display: flex; }
  .nav-links {
    position: fixed; top: 56px; left: 0; right: 0;
    display: none; flex-direction: column; gap: 0; align-items: stretch;
    background: rgba(11,80,101,.98); padding: 8px 5% 14px;
    box-shadow: 0 12px 28px rgba(0,0,0,.18);
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 0; border-bottom: 1px solid rgba(255,255,255,.1); }
  #hero { min-height: auto; padding-top: 86px; }
  .hero-sub { font-size: .95rem; }
  .hero-actions { justify-content: center; }
  section { padding: 56px 5%; }
  .promo-section, .reader-promo-section { padding: 64px 5%; }
  .section-title { font-size: 1.55rem; }
  .product-highlights { grid-template-columns: 1fr; }
  .reader-meta { flex-direction: column; gap: 2px; }
}

@media (max-width: 480px) {
  .nav-logo span:last-child { display: none; }
  .book-scene { height: 285px; transform: scale(.78); transform-origin: center top; margin-bottom: -42px; }
  .stats-grid { display: grid; grid-template-columns: 1fr 1fr; }
  .card-stats { gap: 16px; }
  .version-grid { grid-template-columns: 1fr; }
  .reader-panel { padding: 18px; }
}