:root {
  --color-bg: #f4efe3;
  --color-surface: #fffaf0;
  --color-surface-alt: #e9dfca;
  --color-text: #17231f;
  --color-muted: #62706a;
  --color-primary: #1f5d4d;
  --color-primary-dark: #113d34;
  --color-secondary: #c26b3a;
  --color-accent: #d6ff71;
  --color-border: #cdbf9f;
  --font-heading: Georgia, 'Times New Roman', serif;
  --font-body: Inter, 'Segoe UI', Arial, sans-serif;
  --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;
  --radius-sm: 8px;
  --radius-md: 18px;
  --radius-lg: 34px;
  --shadow-soft: 0 18px 60px rgba(23, 35, 31, .13);
  --shadow-line: 0 1px 0 rgba(23, 35, 31, .1);
  --container: 1160px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--color-text);
  background:
    linear-gradient(90deg, rgba(31,93,77,.055) 1px, transparent 1px) 0 0 / 44px 44px,
    linear-gradient(rgba(31,93,77,.045) 1px, transparent 1px) 0 0 / 44px 44px,
    radial-gradient(circle at 12% 18%, rgba(214,255,113,.28), transparent 27rem),
    radial-gradient(circle at 88% 6%, rgba(194,107,58,.16), transparent 31rem),
    var(--color-bg);
  line-height: 1.6;
}

a { color: var(--color-primary); text-decoration-thickness: .08em; text-underline-offset: .22em; }
a:hover { color: var(--color-secondary); }
img { max-width: 100%; height: auto; display: block; }
svg { max-width: 100%; }
button, input, textarea, select { font: inherit; }

:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

.skip-link {
  position: absolute;
  top: -60px;
  left: 16px;
  z-index: 20;
  padding: 10px 14px;
  color: var(--color-text);
  background: var(--color-accent);
  border-radius: var(--radius-sm);
}
.skip-link:focus { top: 12px; }

.container { width: min(var(--container), calc(100% - 32px)); margin: 0 auto; }
.section { padding: clamp(58px, 8vw, 108px) 0; }
.section-tight { padding: clamp(36px, 5vw, 72px) 0; }
.kicker {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 6px 10px;
  color: var(--color-primary-dark);
  background: rgba(214,255,113,.36);
  border: 1px solid rgba(31,93,77,.18);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .04em;
  text-transform: uppercase;
}
.kicker::before {
  content: '';
  width: 8px;
  height: 8px;
  background: var(--color-primary);
  border-radius: 50%;
  box-shadow: 0 0 0 5px rgba(31,93,77,.1);
}

h1, h2, h3 {
  margin: 0 0 .55em;
  font-family: var(--font-heading);
  line-height: .98;
  letter-spacing: -.045em;
  color: var(--color-primary-dark);
}
h1 { font-size: clamp(2.65rem, 8vw, 6.8rem); max-width: 980px; }
h2 { font-size: clamp(2rem, 5vw, 4.15rem); }
h3 { font-size: clamp(1.25rem, 2.4vw, 1.85rem); letter-spacing: -.025em; }
p { margin: 0 0 1em; }
.lead { font-size: clamp(1.08rem, 2vw, 1.35rem); color: #33423d; max-width: 780px; }
.muted { color: var(--color-muted); }
.microcopy { font-size: .92rem; color: var(--color-muted); }

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(18px);
  background: rgba(244,239,227,.82);
  border-bottom: 1px solid rgba(205,191,159,.68);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 78px;
}
.logo {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--color-primary-dark);
  text-decoration: none;
  font-family: var(--font-heading);
  font-size: 1.2rem;
  letter-spacing: -.03em;
  white-space: nowrap;
}
.logo img { width: 34px; height: 34px; }
.logo span { display: block; font-family: var(--font-mono); font-size: .68rem; color: var(--color-muted); letter-spacing: .06em; text-transform: uppercase; }
.main-nav { display: flex; align-items: center; gap: 4px; flex-wrap: wrap; justify-content: flex-end; }
.main-nav a {
  padding: 9px 12px;
  color: var(--color-text);
  text-decoration: none;
  border-radius: 999px;
  font-size: .95rem;
}
.main-nav a:hover,
.main-nav a[aria-current='page'] {
  background: var(--color-surface);
  box-shadow: var(--shadow-line);
  color: var(--color-primary-dark);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 48px;
  padding: 13px 19px;
  border: 1px solid transparent;
  border-radius: 999px;
  color: #fffdf5;
  background: var(--color-primary);
  text-decoration: none;
  font-weight: 760;
  box-shadow: 0 12px 24px rgba(31,93,77,.18);
  transition: transform .2s ease, box-shadow .2s ease, background .2s ease;
}
.btn:hover { color: #fffdf5; background: var(--color-primary-dark); transform: translateY(-2px); box-shadow: 0 18px 30px rgba(17,61,52,.2); }
.btn.secondary {
  color: var(--color-primary-dark);
  background: transparent;
  border-color: var(--color-border);
  box-shadow: none;
}
.btn.secondary:hover { background: var(--color-surface); color: var(--color-primary-dark); }
.btn.accent { background: var(--color-accent); color: var(--color-primary-dark); box-shadow: 0 12px 24px rgba(31,93,77,.08); }
.btn.accent:hover { background: #c8f45c; color: var(--color-primary-dark); }
.btn-row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }

.hero-lab { padding: clamp(42px, 7vw, 96px) 0 58px; }
.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.03fr) minmax(320px, .72fr);
  gap: clamp(28px, 5vw, 66px);
  align-items: center;
}
.hero-copy { position: relative; }
.hero-copy::after {
  content: 'AI ↔ EN';
  position: absolute;
  right: 2%;
  top: -16px;
  color: rgba(31,93,77,.12);
  font-family: var(--font-mono);
  font-size: clamp(3rem, 8vw, 8.4rem);
  font-weight: 900;
  z-index: -1;
}
.hero-note {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 12px;
  align-items: start;
  margin: 28px 0;
  padding: 16px;
  max-width: 720px;
  background: rgba(255,250,240,.72);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius-md);
}
.hero-note strong { color: var(--color-secondary); }
.console-wrap { position: relative; }
.console-wrap::before {
  content: '';
  position: absolute;
  inset: 16px -18px -20px 18px;
  border: 2px solid rgba(31,93,77,.14);
  border-radius: var(--radius-lg);
  transform: rotate(2deg);
}
.lab-console {
  position: relative;
  padding: 22px;
  background: linear-gradient(145deg, #173a32, #0f2824);
  border: 1px solid rgba(214,255,113,.24);
  border-radius: var(--radius-lg);
  color: #fffaf0;
  box-shadow: var(--shadow-soft);
  overflow: hidden;
}
.lab-console::after {
  content: '';
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(0deg, transparent 0, transparent 12px, rgba(214,255,113,.035) 13px);
  pointer-events: none;
}
.console-top {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
  margin-bottom: 22px;
  font-family: var(--font-mono);
  font-size: .78rem;
  color: rgba(255,250,240,.72);
}
.status-dots { display: flex; gap: 7px; }
.status-dots span { width: 9px; height: 9px; border-radius: 50%; background: var(--color-accent); box-shadow: 0 0 18px rgba(214,255,113,.75); }
.status-dots span:nth-child(2) { background: var(--color-secondary); box-shadow: none; }
.status-dots span:nth-child(3) { background: #fffaf0; box-shadow: none; opacity: .55; }
.prompt-card {
  position: relative;
  padding: 18px 18px 18px 20px;
  background: rgba(255,250,240,.08);
  border: 1px solid rgba(255,250,240,.14);
  border-left: 4px solid var(--color-accent);
  border-radius: 16px;
  margin: 12px 0;
}
.prompt-card .tag {
  display: inline-block;
  margin-bottom: 8px;
  font-family: var(--font-mono);
  font-size: .74rem;
  color: var(--color-accent);
}
.prompt-card p { margin-bottom: 0; }
.console-meter {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-top: 18px;
}
.meter {
  padding: 13px;
  background: rgba(255,250,240,.07);
  border-radius: 14px;
  border: 1px solid rgba(255,250,240,.12);
}
.meter b { display: block; font-family: var(--font-heading); font-size: 1.8rem; color: var(--color-accent); line-height: 1; }
.meter span { font-size: .78rem; color: rgba(255,250,240,.76); }

.feature-rail {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 26px;
}
.rail-item {
  padding: 18px;
  background: rgba(255,250,240,.72);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  min-height: 150px;
}
.rail-item small,
.station-card small,
.route-card small { font-family: var(--font-mono); color: var(--color-secondary); letter-spacing: .04em; text-transform: uppercase; }

.split {
  display: grid;
  grid-template-columns: minmax(0, .9fr) minmax(0, 1.1fr);
  gap: clamp(26px, 5vw, 64px);
  align-items: start;
}
.panel {
  padding: clamp(24px, 4vw, 40px);
  background: rgba(255,250,240,.78);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: 0 14px 40px rgba(23,35,31,.06);
}
.panel.dark {
  color: #fffaf0;
  background: var(--color-primary-dark);
  border-color: rgba(214,255,113,.2);
}
.panel.dark h2, .panel.dark h3 { color: #fffaf0; }
.panel.dark a { color: var(--color-accent); }

.lesson-path {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0 0 0 22px;
}
.lesson-path::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: linear-gradient(var(--color-primary), var(--color-secondary));
}
.lesson-path li {
  position: relative;
  margin: 0 0 18px;
  padding: 16px 16px 16px 18px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.lesson-path li::before {
  content: attr(data-step);
  position: absolute;
  left: -37px;
  top: 18px;
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  color: #fffaf0;
  background: var(--color-primary);
  border: 3px solid var(--color-bg);
  border-radius: 50%;
  font-family: var(--font-mono);
  font-size: .75rem;
}

.neuro-chip-list { display: flex; flex-wrap: wrap; gap: 9px; margin: 18px 0 0; padding: 0; list-style: none; }
.neuro-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 12px;
  border: 1px solid rgba(31,93,77,.2);
  border-radius: 999px;
  background: rgba(255,250,240,.72);
  color: var(--color-primary-dark);
  font-family: var(--font-mono);
  font-size: .82rem;
}
.neuro-chip::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-secondary);
}

.dialogue-strip {
  display: grid;
  gap: 12px;
  padding: 18px;
  background:
    linear-gradient(90deg, rgba(214,255,113,.15), transparent 42%),
    var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}
.dialogue-line {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 12px;
  align-items: start;
}
.dialogue-line b {
  font-family: var(--font-mono);
  font-size: .8rem;
  color: var(--color-secondary);
}
.dialogue-line span {
  padding: 12px 14px;
  border-radius: 14px;
  background: rgba(244,239,227,.9);
  border: 1px solid rgba(205,191,159,.75);
}
.dialogue-line.ai span { background: rgba(31,93,77,.08); border-color: rgba(31,93,77,.22); }

.pronunciation-wave {
  position: relative;
  display: grid;
  grid-template-columns: repeat(15, 1fr);
  gap: 5px;
  align-items: end;
  height: 118px;
  padding: 18px;
  background: var(--color-primary-dark);
  border-radius: var(--radius-md);
  overflow: hidden;
}
.pronunciation-wave::before {
  content: 'shadowing / rhythm / stress';
  position: absolute;
  top: 10px;
  left: 18px;
  color: rgba(255,250,240,.55);
  font-family: var(--font-mono);
  font-size: .72rem;
}
.pronunciation-wave i {
  display: block;
  min-height: 18px;
  border-radius: 999px 999px 5px 5px;
  background: linear-gradient(var(--color-accent), var(--color-secondary));
  opacity: .9;
  animation: wave 3.4s ease-in-out infinite;
}
.pronunciation-wave i:nth-child(2n) { animation-delay: .22s; opacity: .68; }
.pronunciation-wave i:nth-child(3n) { animation-delay: .48s; opacity: 1; }

.pronunciation-wave i:nth-child(1) { height: 44px; }
.pronunciation-wave i:nth-child(2) { height: 82px; }
.pronunciation-wave i:nth-child(3) { height: 58px; }
.pronunciation-wave i:nth-child(4) { height: 96px; }
.pronunciation-wave i:nth-child(5) { height: 48px; }
.pronunciation-wave i:nth-child(6) { height: 72px; }
.pronunciation-wave i:nth-child(7) { height: 101px; }
.pronunciation-wave i:nth-child(8) { height: 62px; }
.pronunciation-wave i:nth-child(9) { height: 88px; }
.pronunciation-wave i:nth-child(10) { height: 54px; }
.pronunciation-wave i:nth-child(11) { height: 77px; }
.pronunciation-wave i:nth-child(12) { height: 43px; }
.pronunciation-wave i:nth-child(13) { height: 93px; }
.pronunciation-wave i:nth-child(14) { height: 66px; }
.pronunciation-wave i:nth-child(15) { height: 51px; }

@keyframes wave { 0%,100% { transform: scaleY(.72); } 50% { transform: scaleY(1.08); } }

.error-lens {
  position: relative;
  padding: 22px;
  background: #fffaf0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
}
.error-lens::before {
  content: '';
  position: absolute;
  right: 24px;
  top: -18px;
  width: 70px;
  height: 70px;
  border: 9px solid rgba(31,93,77,.16);
  border-radius: 50%;
}
.error-lens mark {
  background: linear-gradient(transparent 52%, rgba(214,255,113,.7) 52%);
  padding: 0 2px;
}
.error-lens .fix {
  margin-top: 12px;
  padding: 14px;
  border-left: 4px solid var(--color-secondary);
  background: rgba(194,107,58,.08);
  border-radius: 0 12px 12px 0;
}

.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.route-card,
.station-card,
.article-card {
  position: relative;
  overflow: hidden;
  min-height: 230px;
  padding: 22px;
  background: rgba(255,250,240,.78);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: 0 12px 34px rgba(23,35,31,.05);
}
.route-card::after,
.station-card::after {
  content: '';
  position: absolute;
  right: -42px;
  bottom: -42px;
  width: 128px;
  height: 128px;
  border: 1px solid rgba(31,93,77,.18);
  border-radius: 50%;
}
.route-card:nth-child(2n) { border-radius: 18px 42px 18px 42px; }
.route-card:nth-child(3n) { transform: translateY(18px); }
.card-grid .route-card:hover,
.card-grid .station-card:hover,
.article-card:hover { transform: translateY(-4px); transition: transform .2s ease; }
.card-grid a { text-decoration: none; color: inherit; }

.station-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.station-card {
  min-height: 260px;
  background:
    linear-gradient(135deg, rgba(214,255,113,.2), transparent 42%),
    rgba(255,250,240,.83);
}
.station-card .level {
  display: inline-flex;
  margin-top: 12px;
  padding: 6px 9px;
  border: 1px solid rgba(31,93,77,.18);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: .76rem;
}

.compare-grid {
  display: grid;
  gap: 12px;
}
.compare-row {
  display: grid;
  grid-template-columns: .85fr 1.15fr 1fr;
  gap: 12px;
  padding: 14px;
  background: rgba(255,250,240,.75);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.compare-row.header { background: var(--color-primary-dark); color: #fffaf0; font-family: var(--font-mono); font-size: .82rem; }

.notebook {
  background:
    repeating-linear-gradient(0deg, rgba(31,93,77,.08) 0 1px, transparent 1px 34px),
    var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: clamp(22px, 4vw, 42px);
  box-shadow: var(--shadow-soft);
}
.note-row {
  display: grid;
  grid-template-columns: 180px 1fr;
  gap: 18px;
  padding: 18px 0;
  border-bottom: 1px dashed var(--color-border);
}
.note-row:last-child { border-bottom: 0; }
.note-row b { font-family: var(--font-mono); color: var(--color-secondary); }

.prompt-library { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.prompt-note {
  padding: 20px;
  background: var(--color-primary-dark);
  color: #fffaf0;
  border-radius: 20px;
  border: 1px solid rgba(214,255,113,.24);
}
.prompt-note code {
  display: block;
  margin-top: 12px;
  padding: 14px;
  white-space: pre-wrap;
  color: var(--color-accent);
  background: rgba(255,250,240,.08);
  border-radius: 12px;
  font-family: var(--font-mono);
  font-size: .86rem;
}

.toc {
  position: sticky;
  top: 100px;
  padding: 18px;
  background: rgba(255,250,240,.72);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.toc a { display: block; margin: 9px 0; text-decoration: none; }
.article-body { max-width: 780px; }
.article-body h2 { margin-top: 1.2em; }
.article-body ul,
.article-body ol { padding-left: 1.25rem; }
.article-body li { margin-bottom: .55em; }
.callout {
  margin: 24px 0;
  padding: 18px 20px;
  background: rgba(214,255,113,.25);
  border: 1px solid rgba(31,93,77,.18);
  border-radius: var(--radius-md);
}

.faq-list { display: grid; gap: 13px; }
.faq-item {
  padding: 20px;
  background: rgba(255,250,240,.78);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.faq-item h3 { font-size: 1.28rem; margin-bottom: .45em; }

.lead-form {
  display: grid;
  gap: 14px;
  margin-top: 18px;
}
.field { display: grid; gap: 6px; }
.field span { font-size: .88rem; color: var(--color-muted); }
.field input,
.field textarea,
.field select {
  width: 100%;
  border: 1px solid var(--color-border);
  border-radius: 14px;
  padding: 13px 14px;
  color: var(--color-text);
  background: rgba(255,250,240,.9);
}
.field textarea { min-height: 120px; resize: vertical; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }

.site-footer {
  padding: 42px 0;
  background: var(--color-primary-dark);
  color: rgba(255,250,240,.82);
  margin-top: 40px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 24px;
  align-items: start;
}
.site-footer a { color: var(--color-accent); }
.footer-links { display: flex; flex-wrap: wrap; gap: 12px; justify-content: flex-end; }
.footer-links a { text-decoration: none; }
.footer-logo { color: #fffaf0; font-family: var(--font-heading); font-size: 1.35rem; }

.breadcrumbs {
  margin: 22px 0 0;
  font-size: .9rem;
  color: var(--color-muted);
}
.breadcrumbs a { color: var(--color-muted); }
.page-hero { padding: clamp(40px, 7vw, 82px) 0 34px; }
.page-hero .lead { max-width: 880px; }
.image-card {
  background: rgba(255,250,240,.7);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 18px;
  box-shadow: var(--shadow-soft);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; animation-iteration-count: 1 !important; scroll-behavior: auto !important; transition-duration: .001ms !important; }
}

@media (max-width: 920px) {
  .header-inner { align-items: flex-start; flex-direction: column; padding: 14px 0; }
  .main-nav { justify-content: flex-start; }
  .hero-grid,
  .split,
  .station-layout { grid-template-columns: 1fr; }
  .feature-rail,
  .card-grid { grid-template-columns: 1fr 1fr; }
  .route-card:nth-child(3n) { transform: none; }
  .toc { position: static; }
  .compare-row { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  body { background-size: 34px 34px; }
  .container { width: min(100% - 22px, var(--container)); }
  .main-nav a { padding: 8px 9px; font-size: .9rem; }
  .feature-rail,
  .card-grid,
  .prompt-library,
  .form-grid,
  .footer-grid { grid-template-columns: 1fr; }
  .footer-links { justify-content: flex-start; }
  .console-meter { grid-template-columns: 1fr; }
  .dialogue-line { grid-template-columns: 1fr; }
  .note-row { grid-template-columns: 1fr; }
  .lab-console { padding: 16px; border-radius: 24px; }
  .hero-note { grid-template-columns: 1fr; }
}