/* ============================================================
   Avvmo Landing Page — avvmo.com 主页
   Brand: Learning OS — "Become More."
   Design tokens from style.css (--color-*, --font-*, --space-*, etc.)
   ============================================================ */

/* === Landing Container — internal scroll (body is overflow:hidden) === */

.landing-container {
  display: none;   /* JS 控制可见性: launchLanding() → block */
  height: 100%;
  overflow-y: auto;
  overflow-x: hidden;
  scroll-behavior: smooth;
  background: var(--color-bg-deep);
  color: var(--color-text-primary);
  font-family: var(--font-sans);
}

/* === Sticky Navigation === */

.landing-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  padding: 0 var(--space-8);
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background 0.3s var(--ease-out),
              border-color 0.3s var(--ease-out),
              box-shadow 0.3s var(--ease-out);
}

.landing-nav--scrolled {
  background: rgba(13, 13, 15, 0.85);
  border-bottom: var(--border-subtle);
  box-shadow: 0 1px 8px rgba(0, 0, 0, 0.15);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

[data-theme="light"] .landing-nav--scrolled {
  background: rgba(246, 244, 239, 0.85);
}

/* Nav: brand lockup */

.landing-nav__brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-decoration: none;
  color: var(--color-text-primary);
  font-weight: var(--weight-semibold);
  font-size: var(--text-md);
  letter-spacing: 0.04em;
}

.landing-nav__logo {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  font-size: 20px;
  color: var(--color-accent);
  line-height: 1;
}

/* Nav: anchor links */

.landing-nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  list-style: none;
  margin: 0;
  padding: 0;
}

.landing-nav__links a {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: var(--text-sm);
  font-weight: var(--weight-normal);
  transition: color 0.2s var(--ease-out);
}

.landing-nav__links a:hover {
  color: var(--color-accent);
}

/* Nav: right actions */

.landing-nav__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.landing-nav__cta {
  display: inline-flex;
  align-items: center;
  padding: 6px 16px;
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-bg-deep);
  background: var(--color-accent);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  text-decoration: none;
  transition: background 0.2s var(--ease-out),
              transform 0.2s var(--ease-out);
  white-space: nowrap;
}

.landing-nav__cta:hover {
  background: var(--color-accent-soft);
  transform: translateY(-1px);
}

/* 节点 13（2026-08-24）：landing 登录入口——次级描边按钮（与金色 CTA 区分层级） */

.landing-nav__login {
  display: inline-flex;
  align-items: center;
  padding: 6px 16px;
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
  background: none;
  border: 1px solid var(--color-text-tertiary);
  border-radius: var(--radius-md);
  cursor: pointer;
  white-space: nowrap;
  transition: color 0.2s var(--ease-out),
              border-color 0.2s var(--ease-out);
}

.landing-nav__login:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
}

/* Nav: hamburger */

.landing-nav__hamburger {
  display: none;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: none;
  border: none;
  color: var(--color-text-primary);
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: background 0.15s var(--ease-out);
}

.landing-nav__hamburger:hover {
  background: var(--color-accent-subtle);
}

.landing-nav__hamburger svg {
  width: 20px;
  height: 20px;
}

/* Nav: mobile menu dropdown */

.landing-mobile-menu {
  display: none;
  position: absolute;
  top: 56px;
  left: 0;
  right: 0;
  background: var(--color-bg-surface);
  border-bottom: var(--border-normal);
  padding: var(--space-4) var(--space-8);
  flex-direction: column;
  gap: var(--space-3);
  z-index: 49;
}

.landing-mobile-menu--open {
  display: flex;
}

.landing-mobile-menu a {
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: var(--text-base);
  padding: var(--space-2) 0;
  transition: color 0.15s var(--ease-out);
}

.landing-mobile-menu a:hover {
  color: var(--color-accent);
}

.landing-mobile-menu__theme {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) 0;
  margin-top: var(--space-2);
  border-top: var(--border-subtle);
}

/* === Sections (shared) === */

.landing-section {
  padding: clamp(3rem, 8vw, 6rem) var(--space-8);
}

.landing-section__inner {
  max-width: 1080px;
  margin: 0 auto;
}

.landing-section__eyebrow {
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-3);
}

.landing-section__heading {
  font-size: var(--text-2xl);
  font-weight: var(--weight-light);
  color: var(--color-text-primary);
  line-height: var(--leading-tight);
  margin: 0 0 var(--space-4);
}

.landing-section__heading em {
  font-style: normal;
  color: var(--color-accent);
}

.landing-section__subheading {
  font-size: var(--text-md);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0 0 var(--space-8);
  max-width: 640px;
}

.landing-section--centered {
  text-align: center;
}

.landing-section--centered .landing-section__subheading,
.landing-section__subheading.landing-section--centered {
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

/* === Hero Section === */

.landing-hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 56px);
  padding: var(--space-16) var(--space-8);
  text-align: center;
  position: relative;
  overflow: hidden;
}

/* Background glow */
.landing-hero::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 600px;
  height: 600px;
  transform: translate(-50%, -50%);
  background: radial-gradient(circle, var(--color-accent-subtle) 0%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

.landing-hero > * {
  position: relative;
  z-index: 1;
}

.landing-hero__eyebrow {
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-6);
}

.landing-hero__title {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: var(--weight-light);
  line-height: 1.1;
  color: var(--color-text-primary);
  margin: 0 0 var(--space-8);
  letter-spacing: -0.02em;
}

.landing-hero__title em {
  font-style: normal;
  color: var(--color-accent);
}

.landing-hero__dna {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  max-width: 640px;
  margin: 0 auto var(--space-6);
}

.landing-hero__dna em {
  font-style: normal;
  color: var(--color-accent);
  font-weight: var(--weight-medium);
}

.landing-hero__framing {
  font-size: var(--text-base);
  color: var(--color-text-tertiary);
  max-width: 560px;
  margin: 0 auto var(--space-8);
  line-height: var(--leading-relaxed);
}

.landing-hero__chain {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  flex-wrap: wrap;
  font-size: var(--text-base);
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-10);
}

.landing-hero__chain-step {
  white-space: nowrap;
}

.landing-hero__chain-step--emphasis {
  color: var(--color-accent);
  font-weight: var(--weight-medium);
}

.landing-hero__chain-arrow {
  color: var(--color-text-disabled);
  font-size: var(--text-sm);
}

.landing-hero__actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
}

/* Reset-session link — shown when a previous session exists */
.landing-reset-link {
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
}
.landing-reset-btn {
  background: none;
  border: none;
  color: var(--color-text-tertiary);
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 2px;
  padding: 0;
  transition: color 0.15s var(--ease-out);
}
.landing-reset-btn:hover {
  color: var(--color-error);
}

/* === Language alternation (Hero CN/EN cross-fade) ===
   Dual-span approach: both languages live in the DOM at all times.
   EN (base) is always position:relative — it determines container height.
   CN (overlay) is always position:absolute — floats on top, no height impact.
   Toggle = swap dimmed/visible classes. Height NEVER changes. */

.lang-alt {
  /* container for the dual-span layers; reset transition on container */
}

/* Block-level alternating slots (eyebrow, dna, framing) */
.alt-text-slot {
  position: relative;
  display: block;
}
.alt-text-slot .alt-layer {
  display: block;
  transition: opacity 0.4s var(--ease-out);
}

/* EN — always relative, always the height-determining layer */
.alt-layer--base {
  position: relative;
  opacity: 1;
}

/* CN — always absolute overlay, does not affect layout height.
   Scaled ~14% larger to visually match Latin glyph density. */
.alt-layer--overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  opacity: 0;
  pointer-events: none;
  font-size: 1.14em;
}

/* State toggles */
.alt-layer--overlay.visible {
  opacity: 1;
  pointer-events: auto;
}
.alt-layer--base.dimmed {
  opacity: 0;
}

/* Chain steps: inline-block containers need relative positioning
   for their absolute overlay children */
.landing-hero__chain-step.lang-alt {
  position: relative;
  display: inline-block;
  vertical-align: middle;
}
.landing-hero__chain-step.lang-alt .alt-layer {
  transition: opacity 0.4s var(--ease-out);
}
.landing-hero__chain-step.lang-alt .alt-layer--overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
}

/* Simple wave elements (arrows, emphasis) — no dual layers, just fade */
.landing-hero__chain-arrow.lang-wave,
.landing-hero__chain-step--emphasis.lang-wave {
  transition: opacity 0.4s var(--ease-out);
}
.lang-wave--dimmed {
  opacity: 0;
}

/* === CTA Buttons === */

.landing-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 32px;
  font-size: var(--text-base);
  font-weight: var(--weight-medium);
  font-family: var(--font-sans);
  color: var(--color-bg-deep);
  background: var(--color-accent);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  text-decoration: none;
  transition: background 0.2s var(--ease-out),
              transform 0.2s var(--ease-out),
              box-shadow 0.2s var(--ease-out);
  white-space: nowrap;
}

.landing-cta:hover {
  background: var(--color-accent-soft);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px var(--color-accent-subtle);
}

.landing-cta--ghost {
  background: transparent;
  color: var(--color-accent);
  border: 1px solid var(--color-accent-soft);
}

.landing-cta--ghost:hover {
  background: var(--color-accent-subtle);
  color: var(--color-accent);
}

.landing-cta--large {
  padding: 18px 40px;
  font-size: var(--text-md);
}

/* === Pain Points Grid (3 columns) === */

.landing-pain-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
}

.landing-pain-card {
  position: relative;
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  transition: border-color 0.3s var(--ease-out),
              transform 0.3s var(--ease-out);
}

.landing-pain-card:hover {
  border-color: var(--color-accent-soft);
  transform: translateY(-2px);
}

.landing-pain-card__icon {
  font-size: 1.5rem;
  margin-bottom: var(--space-4);
}

.landing-pain-card__title {
  font-size: var(--text-md);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
  margin: 0 0 var(--space-3);
}

.landing-pain-card__quote {
  font-size: var(--text-sm);
  font-style: italic;
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0 0 var(--space-4);
  padding-left: var(--space-4);
  border-left: 2px solid var(--color-accent-subtle);
}

.landing-pain-card__badge {
  position: absolute;
  top: var(--space-3);
  right: var(--space-4);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-disabled);
  background: var(--color-bg-elevated);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
}

.landing-pain-card__solution {
  font-size: var(--text-sm);
  color: var(--color-accent);
  font-weight: var(--weight-medium);
}

/* === How-it-works 三步 (Path C lead hook) === */

.landing-how-works-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
  margin-top: var(--space-8);
  margin-bottom: var(--space-4);
}

.landing-how-works-card {
  text-align: center;
  padding: var(--space-6) var(--space-4);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border-subtle);
  border-radius: var(--radius-lg);
  transition: transform var(--duration-normal) var(--ease-out),
              box-shadow var(--duration-normal) var(--ease-out),
              border-color var(--duration-normal) var(--ease-out);
}
.landing-how-works-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 20px rgba(196, 162, 101, 0.08);
  border-color: var(--color-accent-soft);
}

.landing-how-works-card__step {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--color-accent-subtle);
  color: var(--color-accent);
  font-size: var(--text-lg);
  font-weight: var(--weight-bold);
  margin-bottom: var(--space-4);
}

.landing-how-works-card h3 {
  font-size: var(--text-base);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
  margin-bottom: var(--space-2);
}

.landing-how-works-card p {
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  line-height: var(--leading-relaxed);
  margin: 0;
}

/* === What-is Cards (accent left border) === */

.landing-what-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
  margin-bottom: var(--space-8);
}

.landing-what-card {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-left: 3px solid var(--color-accent);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: var(--space-6);
}

.landing-what-card__tag {
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  color: var(--color-text-disabled);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-2);
}

.landing-what-card__not {
  color: var(--color-error);
  font-weight: var(--weight-medium);
  margin-right: var(--space-1);
}

.landing-what-card__is {
  color: var(--color-success);
  font-weight: var(--weight-medium);
}

.landing-what-card__text {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin-top: var(--space-2);
}

/* Not-box */

.landing-not-box {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-6) var(--space-8);
  max-width: 720px;
  margin: 0 auto;
}

.landing-not-box p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin: 0 0 var(--space-2);
  line-height: var(--leading-relaxed);
}

.landing-not-box p:last-child {
  margin-bottom: 0;
}

.landing-not-box strong {
  color: var(--color-text-primary);
}

/* === 7-step flow strip === */

.landing-flow-strip {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  flex-wrap: wrap;
  margin-top: var(--space-8);
  font-size: var(--text-sm);
}

.landing-flow-step {
  background: var(--color-bg-elevated);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.landing-flow-arrow {
  color: var(--color-text-disabled);
  font-size: var(--text-xs);
}

/* === Direction Narrative === */

.landing-direction-chain {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-6);
  margin-bottom: var(--space-10);
}

.landing-direction-step {
  text-align: center;
  padding: var(--space-6);
}

.landing-direction-step__label {
  font-size: var(--text-lg);
  font-weight: var(--weight-light);
  color: var(--color-accent);
  margin-bottom: var(--space-3);
}

.landing-direction-step__text {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

/* AVM trio */

.landing-avm-trio {
  display: flex;
  justify-content: center;
  gap: var(--space-8);
  flex-wrap: wrap;
}

.landing-avm-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-6);
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  min-width: 160px;
}

.landing-avm-card__letter {
  font-size: var(--text-3xl);
  font-weight: var(--weight-light);
  color: var(--color-accent);
  line-height: 1;
}

.landing-avm-card__label {
  font-size: var(--text-xs);
  color: var(--color-text-secondary);
  text-align: center;
  line-height: var(--leading-relaxed);
}

/* === 30-Second Differentiation Timeline === */

.landing-steps {
  max-width: 800px;
  margin: 0 auto;
  position: relative;
}

.landing-steps::before {
  content: '';
  position: absolute;
  left: 31px;
  top: 0;
  bottom: 0;
  width: 1px;
  background: var(--border-normal);
}

.landing-step-card {
  display: flex;
  gap: var(--space-6);
  margin-bottom: var(--space-10);
  position: relative;
}

.landing-step-card:last-child {
  margin-bottom: 0;
}

.landing-step-card__num {
  flex-shrink: 0;
  width: 64px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-lg);
  font-weight: var(--weight-light);
  color: var(--color-accent);
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-full);
  position: relative;
  z-index: 1;
}

.landing-step-card__content {
  flex: 1;
}

.landing-step-card__title {
  font-size: var(--text-md);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
  margin: 0 0 var(--space-3);
}

/* Mock dialogue bubbles */

.landing-mock-chat {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  margin-bottom: var(--space-3);
}

.landing-mock-chat__user {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}

.landing-mock-chat__user-bubble {
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-accent-soft);
  border-radius: var(--radius-md) var(--radius-md) 4px var(--radius-md);
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  max-width: 70%;
}

.landing-mock-chat__label {
  font-size: var(--text-xs);
  color: var(--color-text-disabled);
  margin-bottom: var(--space-1);
}

.landing-mock-chat__ai-bubble {
  background: var(--color-accent-subtle);
  border-radius: var(--radius-md) var(--radius-md) var(--radius-md) 4px;
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-sm);
  color: var(--color-text-primary);
  max-width: 80%;
  margin-left: auto;
}

.landing-mock-roadmap {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-left: 3px solid var(--color-accent);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: var(--space-5) var(--space-6);
}

.landing-mock-roadmap__title {
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
  margin-bottom: var(--space-3);
}

.landing-mock-roadmap__phase {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) 0;
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
}

.landing-mock-roadmap__phase-num {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: var(--radius-full);
  background: var(--color-accent);
  color: var(--color-bg-deep);
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
  flex-shrink: 0;
}

.landing-step-card__insight {
  font-size: var(--text-sm);
  color: var(--color-accent);
  font-weight: var(--weight-medium);
  font-style: italic;
  margin-top: var(--space-2);
}

/* === Course Cards (2×2 grid) === */

.landing-course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
}

.landing-course-card {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  cursor: pointer;
  transition: border-color 0.3s var(--ease-out),
              transform 0.3s var(--ease-out),
              box-shadow 0.3s var(--ease-out);
  position: relative;
}

.landing-course-card:hover {
  border-color: var(--color-accent-soft);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
}

.landing-course-card__icon {
  font-size: 2rem;
  margin-bottom: var(--space-4);
}

.landing-course-card__tag {
  position: absolute;
  top: var(--space-4);
  right: var(--space-4);
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  padding: 2px 10px;
  border-radius: var(--radius-full);
  background: var(--color-accent-subtle);
  color: var(--color-accent);
}

.landing-course-card__title {
  font-size: var(--text-md);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
  margin: 0 0 var(--space-2);
}

.landing-course-card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0 0 var(--space-4);
}

.landing-course-card__meta {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
}

.landing-course-card__btn {
  margin-top: var(--space-5);
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-accent);
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  transition: color 0.15s var(--ease-out);
}

.landing-course-card__btn:hover {
  color: var(--color-accent-soft);
}

/* Custom-input card — full width, animated CTA */

.landing-course-card--custom {
  grid-column: 1 / -1;          /* span full row */
  border-style: dashed;
  border-color: var(--color-accent-soft);
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: center;
  gap: var(--space-8);
  text-align: left;
  min-height: 120px;
  animation: custom-card-breathe 3s ease-in-out infinite;
  overflow: hidden;
}

/* Breathing glow — border pulses gently */
@keyframes custom-card-breathe {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(196, 162, 101, 0);
    border-color: var(--color-accent-soft);
  }
  50% {
    box-shadow: 0 0 24px 4px rgba(196, 162, 101, 0.15);
    border-color: var(--color-accent);
  }
}

.landing-course-card--custom:hover {
  animation: none;
  border-color: var(--color-accent);
  box-shadow: 0 8px 32px rgba(196, 162, 101, 0.25);
  transform: translateY(-2px);
}

.landing-course-card--custom .landing-course-card__icon {
  font-size: 2.5rem;
  margin-bottom: 0;
  flex-shrink: 0;
  animation: custom-icon-float 2.5s ease-in-out infinite;
}

@keyframes custom-icon-float {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-6px); }
}

.landing-course-card--custom:hover .landing-course-card__icon {
  animation: none;
}

.landing-course-card__custom-body {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.landing-course-card--custom .landing-course-card__title {
  margin: 0;
}

.landing-course-card--custom .landing-course-card__desc {
  margin: 0;
  max-width: 400px;
}

.landing-course-card__custom-hint {
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-accent);
  opacity: 0;
  transform: translateX(-8px);
  transition: opacity 0.3s var(--ease-out),
              transform 0.3s var(--ease-out);
  white-space: nowrap;
  flex-shrink: 0;
}

.landing-course-card--custom:hover .landing-course-card__custom-hint {
  opacity: 1;
  transform: translateX(0);
}

/* === Lesson 0 === */

.landing-lesson0 {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-10);
  max-width: 800px;
  margin: 0 auto;
}

.landing-lesson0__phases {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--space-4);
  margin: var(--space-6) 0;
}

.landing-lesson0__phase {
  display: flex;
  align-items: flex-start;
  gap: var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

.landing-lesson0__phase-num {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: var(--radius-full);
  background: var(--color-accent);
  color: var(--color-bg-deep);
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
}

.landing-lesson0__hook {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  font-style: italic;
  margin: var(--space-6) 0;
  padding: var(--space-4);
  border-left: 3px solid var(--color-accent);
  background: var(--color-bg-elevated);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.landing-lesson0__actions {
  text-align: center;
  margin-top: var(--space-6);
}

/* === Testimonials === */

.landing-testimonial-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
  margin-bottom: var(--space-8);
}

.landing-testimonial-card {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-left: 3px solid var(--color-accent);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: var(--space-6);
  position: relative;
}

.landing-testimonial-card__badge {
  position: absolute;
  top: var(--space-3);
  right: var(--space-4);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-disabled);
  background: var(--color-bg-elevated);
  padding: 2px 8px;
  border-radius: var(--radius-full);
}

.landing-testimonial-card__quote {
  font-size: var(--text-sm);
  font-style: italic;
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0 0 var(--space-4);
}

.landing-testimonial-card__author {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.landing-testimonial-card__avatar {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--color-accent-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-sm);
  color: var(--color-accent);
}

.landing-testimonial-card__name {
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
}

.landing-testimonial-card__role {
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
}

/* Social proof stat */

.landing-social-proof {
  text-align: center;
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  padding: var(--space-6);
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  max-width: 520px;
  margin: 0 auto;
}

.landing-social-proof strong {
  color: var(--color-accent);
  font-weight: var(--weight-medium);
}

.landing-social-proof__link {
  background: none;
  border: none;
  padding: 0;
  color: var(--color-accent);
  font-size: inherit;
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.landing-social-proof__link:hover {
  color: var(--color-accent-soft);
}

/* === Pricing === */

.landing-pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-6);
  margin-bottom: var(--space-8);
}

.landing-pricing-card {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  text-align: center;
  transition: border-color 0.3s var(--ease-out),
              transform 0.3s var(--ease-out);
}

.landing-pricing-card:hover {
  border-color: var(--color-accent-soft);
  transform: translateY(-2px);
}

.landing-pricing-card--featured {
  border-color: var(--color-accent-soft);
  box-shadow: 0 0 24px var(--color-accent-subtle);
}

.landing-pricing-card__type {
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-2);
}

.landing-pricing-card__price {
  font-size: var(--text-xl);
  font-weight: var(--weight-light);
  color: var(--color-accent);
  margin-bottom: var(--space-1);
}

.landing-pricing-card__lessons {
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-6);
}

.landing-pricing-card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

/* Efficient Learning Gold explainer */

.landing-gold-explainer {
  background: var(--color-bg-surface);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  max-width: 680px;
  margin: 0 auto var(--space-4);
  text-align: left;
}

.landing-gold-explainer__title {
  font-size: var(--text-md);
  font-weight: var(--weight-medium);
  color: var(--color-accent);
  margin: 0 0 var(--space-3);
}

.landing-gold-explainer__text {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0;
}

.landing-anti-sub {
  text-align: center;
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  max-width: 560px;
  margin: 0 auto;
  line-height: var(--leading-relaxed);
}

/* === Final CTA Section === */

.landing-final-cta {
  text-align: center;
  padding: clamp(4rem, 10vw, 8rem) var(--space-8);
  position: relative;
  overflow: hidden;
}

.landing-final-cta::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 500px;
  height: 500px;
  transform: translate(-50%, -50%);
  background: radial-gradient(circle, var(--color-accent-subtle) 0%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

.landing-final-cta > * {
  position: relative;
  z-index: 1;
}

.landing-final-cta__title {
  font-size: var(--text-2xl);
  font-weight: var(--weight-light);
  color: var(--color-text-primary);
  margin: 0 0 var(--space-4);
}

.landing-final-cta__sub {
  font-size: var(--text-md);
  color: var(--color-text-secondary);
  margin: 0 0 var(--space-8);
  line-height: var(--leading-relaxed);
}

.landing-final-cta__actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
}

.landing-final-cta__link {
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  text-decoration: none;
  transition: color 0.15s var(--ease-out);
  cursor: pointer;
  background: none;
  border: none;
  font-family: var(--font-sans);
}

.landing-final-cta__link:hover {
  color: var(--color-accent);
}

/* === Three Identities (三重身份) === */

.landing-identities-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
  margin-top: var(--space-10);
}

.landing-identity-card {
  background: var(--color-bg-elevated);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  transition: border-color 0.3s var(--ease-out), transform 0.3s var(--ease-out);
}

.landing-identity-card:hover {
  border-color: var(--color-accent-soft);
  transform: translateY(-2px);
}

.landing-identity-card__icon {
  font-size: 2rem;
  line-height: 1;
}

.landing-identity-card__title {
  font-size: var(--text-lg);
  font-weight: var(--weight-semibold);
  color: var(--color-text-primary);
  margin: 0;
}

.landing-identity-card__title em {
  color: var(--color-accent);
  font-style: normal;
}

.landing-identity-card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0;
  flex: 1;
}

.landing-identity-card__chat {
  margin-top: var(--space-2);
}

.landing-identity-card__chat .landing-mock-chat {
  background: var(--color-bg-deep);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  border: var(--border-subtle);
}

.landing-identity-card__chat .landing-mock-chat__ai-bubble {
  font-size: var(--text-xs);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  font-style: italic;
}

/* === Science Grid (背后的学习科学) === */

.landing-science-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6);
  margin-top: var(--space-10);
}

.landing-science-card {
  background: var(--color-bg-elevated);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  transition: border-color 0.3s var(--ease-out);
}

.landing-science-card:hover {
  border-color: var(--color-accent-soft);
}

.landing-science-card__header {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
}

.landing-science-card__icon {
  font-size: 1.5rem;
  line-height: 1;
  flex-shrink: 0;
  margin-top: 2px;
}

.landing-science-card__title {
  font-size: var(--text-base);
  font-weight: var(--weight-semibold);
  color: var(--color-text-primary);
  margin: 0;
}

.landing-science-card__author {
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  margin: 2px 0 0;
}

.landing-science-card__quote {
  font-size: var(--text-sm);
  color: var(--color-accent);
  font-style: italic;
  line-height: var(--leading-relaxed);
  margin: 0;
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg-deep);
  border-radius: var(--radius-md);
  border-left: 2px solid var(--color-accent-soft);
}

.landing-science-card__apply {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0;
}

/* === Science bridge → rigor spine === */

.landing-science-bridge {
  margin-top: var(--space-6);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  text-align: center;
}

/* === Rigor Spine: 说到做到 === */

.landing-rigor-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-4);
  margin-top: var(--space-10);
}

.landing-rigor-card {
  background: var(--color-bg-elevated);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: border-color 0.3s var(--ease-out);
}

.landing-rigor-card:hover {
  border-color: var(--color-accent-soft);
}

.landing-rigor-card__title {
  font-size: var(--text-base);
  font-weight: var(--weight-semibold);
  color: var(--color-text-primary);
  margin: 0 0 var(--space-2);
}

.landing-rigor-card__title::before {
  content: "✓ ";
  color: var(--color-accent);
}

.landing-rigor-card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0;
}

.landing-rigor-close {
  margin: var(--space-8) auto 0;
  max-width: 480px;
  text-align: center;
  font-size: var(--text-md);
  color: var(--color-text-primary);
  padding: var(--space-4);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-accent-soft);
  border-radius: var(--radius-md);
}

.landing-rigor-close strong {
  color: var(--color-accent);
  font-weight: var(--weight-semibold);
}

/* === Responsive: stack on mobile === */

@media (max-width: 768px) {
  .landing-identities-grid {
    grid-template-columns: 1fr;
  }

  .landing-science-grid {
    grid-template-columns: 1fr;
  }
}

/* === Footer === */

.landing-footer {
  text-align: center;
  padding: var(--space-8) var(--space-8) var(--space-10);
  border-top: var(--border-subtle);
}

.landing-footer__dna {
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  font-style: italic;
  max-width: 480px;
  margin: 0 auto var(--space-4);
  line-height: var(--leading-relaxed);
}

.landing-footer__brand {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  font-weight: var(--weight-medium);
  margin-bottom: var(--space-3);
}

.landing-footer__links {
  display: flex;
  justify-content: center;
  gap: var(--space-6);
  flex-wrap: wrap;
  margin-bottom: var(--space-4);
}

.landing-footer__links a {
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  text-decoration: none;
  transition: color 0.15s var(--ease-out);
}

.landing-footer__links a:hover {
  color: var(--color-accent);
}

.landing-footer__copy {
  font-size: var(--text-xs);
  color: var(--color-text-disabled);
}

/* === Scroll Reveal Animations === */

.landing-reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.6s var(--ease-out),
              transform 0.6s var(--ease-out);
}

.landing-reveal--visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  .landing-reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* ============================================================
   Responsive
   ============================================================ */

/* ≤ 900px — collapse grids to 2 columns, hide some nav links */
@media (max-width: 900px) {
  .landing-nav__links {
    display: none;
  }

  .landing-nav__hamburger {
    display: flex;
  }

  .landing-hero__title {
    font-size: clamp(2rem, 8vw, 3rem);
  }

  .landing-course-grid {
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  }

  .landing-rigor-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ≤ 640px — single column, stack everything */
@media (max-width: 640px) {
  .landing-nav {
    padding: 0 var(--space-4);
  }

  .landing-nav__cta {
    padding: 6px 12px;
    font-size: var(--text-xs);
  }

  .landing-section {
    padding: var(--space-10) var(--space-4);
  }

  .landing-section__heading {
    font-size: var(--text-xl);
  }

  .landing-hero {
    min-height: calc(100vh - 56px);
    padding: var(--space-10) var(--space-4);
  }

  .landing-hero__title {
    font-size: clamp(1.75rem, 10vw, 2.5rem);
  }

  .landing-hero__dna {
    font-size: var(--text-base);
  }

  .landing-hero__chain {
    font-size: var(--text-xs);
    gap: var(--space-2);
  }

  .landing-how-works-grid,
  .landing-pain-grid,
  .landing-what-grid,
  .landing-course-grid,
  .landing-testimonial-grid,
  .landing-pricing-grid,
  .landing-rigor-grid {
    grid-template-columns: 1fr;
    gap: var(--space-4);
  }

  .landing-course-card--custom {
    flex-direction: column;
    text-align: center;
    gap: var(--space-4);
    padding: var(--space-6);
  }

  .landing-course-card__custom-hint {
    opacity: 1;
    transform: none;
  }

  .landing-direction-chain {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-4);
  }

  .landing-lesson0 {
    padding: var(--space-6);
  }

  .landing-lesson0__phases {
    grid-template-columns: 1fr 1fr;
  }

  .landing-step-card {
    gap: var(--space-4);
  }

  .landing-step-card__num {
    width: 48px;
    height: 48px;
    font-size: var(--text-base);
  }

  .landing-steps::before {
    left: 23px;
  }

  .landing-mock-chat__user-bubble,
  .landing-mock-chat__ai-bubble {
    max-width: 90%;
  }

  .landing-avm-trio {
    gap: var(--space-4);
  }

  .landing-avm-card {
    min-width: 100px;
    padding: var(--space-4);
  }

  .landing-final-cta__title {
    font-size: var(--text-xl);
  }

  .landing-footer__links {
    gap: var(--space-4);
  }
}