/* =================================================================
   Leaf Bubble Design System — Inkling Lingua landing page
   Brand source: extension/RULES.md §R12, STORE_DESCRIPTION.md
   ================================================================= */

/* -----------------------------------------------------------------
   1. Tokens
   ----------------------------------------------------------------- */
:root {
  /* Palette */
  --paper:        #FBF8F0;
  --paper-deep:   #F4EFE2;
  --paper-edge:   #ECE4D0;
  --moss:         #3D9980;
  --moss-deep:    #2F7A66;
  --moss-soft:    #6FB8A4;
  --moss-tint:    #E5F2EE;
  --ink:          #2A2A2A;
  --ink-soft:     #4A4A4A;
  --ink-mute:     #7A7A7A;
  --ink-faint:    #B5B0A4;
  --shadow-leaf:  0 8px 24px -8px rgba(60, 80, 70, 0.18),
                  0 2px 6px  -2px rgba(60, 80, 70, 0.08);
  --shadow-card:  0 18px 40px -16px rgba(60, 80, 70, 0.22),
                  0 4px 12px  -4px rgba(60, 80, 70, 0.10);

  /* Geometry */
  --radius-card:  14px;
  --radius-pill:  999px;
  --radius-sm:    8px;

  /* Motion */
  --ease-leaf:    cubic-bezier(.22, .61, .36, 1);
  --t-fast:       150ms;
  --t-mid:        220ms;
  --t-slow:       420ms;

  /* Type */
  --font-sans:    "Instrument Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-cn:      "Noto Serif SC", "LXGW WenKai Screen", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", serif;

  /* Layout */
  --container:    1140px;
  --gutter:       1.5rem;
}

/* -----------------------------------------------------------------
   2. Reset
   ----------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Paper-grain background — subtle SVG noise */
body {
  background-color: var(--paper);
  background-image:
    radial-gradient(ellipse 800px 400px at 50% -10%, rgba(61, 153, 128, 0.08), transparent 60%),
    url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='120' height='120'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 0.95  0 0 0 0 0.92  0 0 0 0 0.85  0 0 0 0.04 0'/></filter><rect width='100%' height='100%' filter='url(%23n)'/></svg>");
  background-attachment: fixed;
}

img, svg { display: block; max-width: 100%; }
button { font: inherit; cursor: pointer; }
a { color: inherit; text-decoration: none; transition: color var(--t-fast) var(--ease-leaf); }
a:hover { color: var(--moss); }

:lang(zh), :lang(zh-CN), [lang^="zh"] { font-family: var(--font-cn), var(--font-sans); }
html[lang^="zh"] body { font-family: var(--font-cn); }
html[lang^="zh"] h1, html[lang^="zh"] h2, html[lang^="zh"] h3 { font-family: var(--font-cn); letter-spacing: 0.01em; }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

/* -----------------------------------------------------------------
   3. Nav
   ----------------------------------------------------------------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(12px) saturate(140%);
  -webkit-backdrop-filter: blur(12px) saturate(140%);
  background: rgba(251, 248, 240, 0.78);
  border-bottom: 1px solid rgba(60, 80, 70, 0.08);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: 1rem;
}
.brand { display: inline-flex; align-items: center; gap: 0.55rem; font-weight: 600; }
.brand-icon { width: 28px; height: 28px; color: var(--moss); }
.brand-text { font-size: 1.06rem; letter-spacing: 0.005em; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.6rem;
  font-size: 0.94rem;
  color: var(--ink-soft);
}
.nav-links a {
  position: relative;
  padding: 0.25rem 0;
}
.nav-links a::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: -2px;
  height: 2px; background: var(--moss);
  transform: scaleX(0); transform-origin: left;
  transition: transform var(--t-mid) var(--ease-leaf);
}
.nav-links a:hover::after { transform: scaleX(1); }

.lang-toggle {
  border: 1px solid rgba(60, 80, 70, 0.18);
  background: transparent;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-pill);
  font-size: 0.86rem;
  color: var(--ink-soft);
  letter-spacing: 0.04em;
  transition: all var(--t-fast) var(--ease-leaf);
}
.lang-toggle:hover { border-color: var(--moss); color: var(--moss); }
.lang-toggle [data-lang-label] { font-weight: 500; }
.lang-toggle [data-lang-label].is-active { color: var(--moss); font-weight: 700; }
.lang-sep { margin: 0 0.35rem; color: var(--ink-faint); }

@media (max-width: 720px) {
  .nav-links { display: none; }
}

/* -----------------------------------------------------------------
   4. Hero
   ----------------------------------------------------------------- */
.hero {
  padding: 4.5rem 0 3.5rem;
}
.hero-inner {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 4rem;
  align-items: center;
}
@media (max-width: 920px) {
  .hero-inner { grid-template-columns: 1fr; gap: 2.5rem; }
}

.eyebrow {
  display: inline-block;
  font-size: 0.82rem;
  letter-spacing: 0.06em;
  color: var(--moss-deep);
  background: var(--moss-tint);
  padding: 0.32rem 0.85rem;
  border-radius: var(--radius-pill);
  margin-bottom: 1.2rem;
  font-weight: 500;
}

.hero-title {
  margin: 0 0 1.2rem;
  font-size: clamp(2rem, 4.4vw, 3.4rem);
  line-height: 1.15;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink);
}
.hero-plus {
  display: inline-block;
  margin: 0 0.35rem;
  color: var(--moss);
  transform: translateY(-0.08em);
}
.hero-sub {
  margin: 0 0 2rem;
  font-size: 1.08rem;
  color: var(--ink-soft);
  max-width: 32em;
}

.hero-ctas { display: flex; flex-wrap: wrap; gap: 0.8rem; margin-bottom: 1rem; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.78rem 1.4rem;
  border-radius: var(--radius-pill);
  font-size: 0.96rem;
  font-weight: 500;
  border: 1px solid transparent;
  transition: all var(--t-mid) var(--ease-leaf);
  white-space: nowrap;
}
.btn-icon { width: 16px; height: 16px; }
.btn-primary {
  background: var(--moss);
  color: #fff;
  box-shadow: var(--shadow-leaf);
}
.btn-primary:hover {
  background: var(--moss-deep);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 12px 28px -10px rgba(47, 122, 102, 0.45);
}
.btn-primary.is-disabled {
  background: var(--paper-edge);
  color: var(--ink-mute);
  box-shadow: none;
  cursor: not-allowed;
  pointer-events: none;
}
.btn-secondary {
  background: transparent;
  color: var(--ink);
  border-color: rgba(60, 80, 70, 0.20);
}
.btn-secondary:hover {
  border-color: var(--moss);
  color: var(--moss);
  transform: translateY(-1px);
}

.hero-meta {
  font-size: 0.86rem;
  color: var(--ink-mute);
  margin: 0;
}

/* Hero mockup ------------------------------------------------- */
.hero-mockup {
  position: relative;
  min-height: 360px;
}
.mockup-page {
  background: #fff;
  border-radius: var(--radius-card);
  padding: 1.6rem;
  box-shadow: var(--shadow-leaf);
  border: 1px solid var(--paper-edge);
  position: relative;
  z-index: 1;
}
.mockup-page-line {
  height: 10px;
  border-radius: 4px;
  background: var(--paper-deep);
  margin-bottom: 0.65rem;
}
.mockup-page-line:last-child { margin-bottom: 0; }
.mockup-page-line.short { width: 60%; }
.mockup-selected {
  display: inline-block;
  padding: 0 4px;
  background: rgba(61, 153, 128, 0.18);
  border-radius: 3px;
  color: var(--moss-deep);
  font-weight: 600;
  font-size: 0.9rem;
  vertical-align: -2px;
  font-family: var(--font-sans);
}
.mockup-page-line:nth-child(3) {
  background: transparent;
  height: auto;
  display: flex;
  align-items: center;
  gap: 8px;
}
.mockup-page-line:nth-child(3)::before,
.mockup-page-line:nth-child(3)::after {
  content: ""; flex: 1 1 auto; height: 10px; border-radius: 4px;
  background: var(--paper-deep);
}
.mockup-page-line:nth-child(3)::before { max-width: 35%; }

.mockup-card {
  position: absolute;
  right: -8px;
  bottom: -20px;
  width: 280px;
  background: #fff;
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-card);
  border: 1px solid var(--paper-edge);
  overflow: hidden;
  z-index: 2;
  animation: cardFloat 6s var(--ease-leaf) infinite;
}
@keyframes cardFloat {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}
.mockup-card-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.7rem 1rem;
  background: var(--moss-tint);
  border-bottom: 1px solid rgba(60, 80, 70, 0.06);
}
.mockup-card-tag {
  font-size: 0.74rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--moss-deep);
  text-transform: uppercase;
}
.mockup-card-dot {
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--moss);
  animation: dotPulse 2s ease-in-out infinite;
}
@keyframes dotPulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.4; transform: scale(0.85); }
}
.mockup-card-body { padding: 1rem; }
.mockup-card-tx {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 0.5rem;
  font-family: var(--font-cn);
}
.mockup-card-divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--paper-edge), transparent);
  margin: 0.6rem 0;
}
.mockup-card-wiki-title {
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--moss-deep);
  margin-bottom: 0.35rem;
  font-family: var(--font-cn);
}
.mockup-card-wiki-body {
  font-size: 0.82rem;
  color: var(--ink-soft);
  line-height: 1.55;
  font-family: var(--font-cn);
}
.mockup-card-foot {
  padding: 0.6rem 1rem;
  border-top: 1px solid var(--paper-edge);
  background: var(--paper);
  display: flex; justify-content: flex-end;
}
.mockup-card-btn {
  background: var(--moss);
  color: #fff;
  border: none;
  padding: 0.36rem 0.85rem;
  border-radius: var(--radius-pill);
  font-size: 0.78rem;
  font-weight: 500;
  font-family: var(--font-cn);
}

/* -----------------------------------------------------------------
   5. Section common
   ----------------------------------------------------------------- */
section { padding: 4rem 0; }
.section-head { text-align: center; margin-bottom: 3rem; }
.section-title {
  margin: 0 0 0.5rem;
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -0.005em;
}
.section-sub {
  margin: 0;
  color: var(--ink-mute);
  font-size: 1.02rem;
}

/* -----------------------------------------------------------------
   6. Features
   ----------------------------------------------------------------- */
.features {
  background:
    linear-gradient(180deg, transparent, var(--paper-deep) 40%, var(--paper-deep) 60%, transparent);
}
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.4rem;
}
.feature-card {
  background: #fff;
  border: 1px solid var(--paper-edge);
  border-radius: var(--radius-card);
  padding: 1.8rem 1.6rem;
  box-shadow: var(--shadow-leaf);
  transition: transform var(--t-mid) var(--ease-leaf),
              box-shadow var(--t-mid) var(--ease-leaf),
              border-color var(--t-mid) var(--ease-leaf);
}
.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card);
  border-color: var(--moss-soft);
}
.feature-icon {
  font-size: 2rem;
  margin-bottom: 0.85rem;
  line-height: 1;
}
.feature-title {
  margin: 0 0 0.6rem;
  font-size: 1.18rem;
  font-weight: 600;
  color: var(--ink);
}
.feature-text {
  margin: 0;
  font-size: 0.94rem;
  color: var(--ink-soft);
  line-height: 1.65;
}

/* -----------------------------------------------------------------
   7. Design philosophy
   ----------------------------------------------------------------- */
.design-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}
@media (max-width: 920px) {
  .design-inner { grid-template-columns: 1fr; }
}
.design-text {
  font-size: 1.04rem;
  color: var(--ink-soft);
  margin: 0 0 2rem;
  max-width: 32em;
}
.design-tokens {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.85rem 1.2rem;
}
.design-tokens li {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 0.9rem;
  color: var(--ink-soft);
}
.design-tokens code {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.82rem;
  color: var(--ink);
  background: var(--paper-deep);
  padding: 0.15rem 0.45rem;
  border-radius: 4px;
}
.token-swatch {
  width: 22px; height: 22px;
  border-radius: 6px;
  flex-shrink: 0;
  background: var(--moss);
}
.token-radius {
  background: var(--moss-tint);
  border: 2px solid var(--moss);
  border-radius: 7px;
}
.token-easing {
  background: linear-gradient(135deg, var(--moss-tint), var(--moss));
}

/* Sample card stack */
.design-sample {
  position: relative;
  height: 320px;
  display: flex;
  justify-content: center;
  align-items: center;
}
.sample-card {
  position: absolute;
  background: #fff;
  border: 1px solid var(--paper-edge);
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-leaf);
  padding: 1.2rem;
  width: 240px;
}
.sample-card-a { transform: rotate(-6deg) translate(-90px, -40px); }
.sample-card-b { transform: rotate(2deg) translate(20px, 0); z-index: 2; box-shadow: var(--shadow-card); }
.sample-card-c { transform: rotate(7deg) translate(110px, 50px); }
.sample-line {
  height: 8px;
  border-radius: 4px;
  background: var(--paper-deep);
  margin-bottom: 0.55rem;
}
.sample-line:last-child { margin-bottom: 0; }
.sample-line.w40 { width: 40%; }
.sample-line.w50 { width: 50%; }
.sample-line.w60 { width: 60%; }
.sample-line.w70 { width: 70%; }
.sample-line.w80 { width: 80%; }
.sample-line.w90 { width: 90%; }
.sample-card-b .sample-line:first-child { background: var(--moss-tint); }

/* -----------------------------------------------------------------
   8. Privacy
   ----------------------------------------------------------------- */
.privacy {
  background:
    linear-gradient(180deg, transparent, var(--moss-tint) 30%, var(--moss-tint) 70%, transparent);
}
.privacy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.4rem;
}
.privacy-item {
  background: #fff;
  border-radius: var(--radius-card);
  padding: 1.6rem 1.4rem;
  border: 1px solid rgba(60, 80, 70, 0.10);
  text-align: center;
}
.privacy-check {
  display: inline-flex;
  align-items: center; justify-content: center;
  width: 40px; height: 40px;
  border-radius: 50%;
  background: var(--moss);
  color: #fff;
  font-weight: 700;
  margin-bottom: 0.85rem;
  box-shadow: 0 4px 10px -3px rgba(61, 153, 128, 0.45);
}
.privacy-item h3 {
  margin: 0 0 0.4rem;
  font-size: 1.08rem;
  font-weight: 600;
}
.privacy-item p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--ink-soft);
  line-height: 1.55;
}

/* -----------------------------------------------------------------
   9. Invite
   ----------------------------------------------------------------- */
.invite {
  padding: 5rem 0;
}
.invite-inner {
  max-width: 720px;
  text-align: center;
}
.invite-text {
  margin: 0 auto 2rem;
  font-size: 1.04rem;
  color: var(--ink-soft);
  max-width: 36em;
}
.invite-form {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  max-width: 520px;
  margin: 0 auto;
}
.invite-form input[type="email"] {
  flex: 1 1 240px;
  min-width: 0;
  padding: 0.78rem 1.1rem;
  border-radius: var(--radius-pill);
  border: 1px solid rgba(60, 80, 70, 0.18);
  background: #fff;
  font-size: 0.98rem;
  color: var(--ink);
  font-family: inherit;
  transition: border-color var(--t-fast) var(--ease-leaf),
              box-shadow var(--t-fast) var(--ease-leaf);
}
.invite-form input[type="email"]:focus {
  outline: none;
  border-color: var(--moss);
  box-shadow: 0 0 0 3px rgba(61, 153, 128, 0.18);
}
.invite-status {
  flex-basis: 100%;
  margin: 0.6rem 0 0;
  font-size: 0.9rem;
  min-height: 1.4em;
}
.invite-status.is-success { color: var(--moss-deep); }
.invite-status.is-error   { color: #B8482E; }

/* -----------------------------------------------------------------
   10. Footer
   ----------------------------------------------------------------- */
.footer {
  padding: 3rem 0 2rem;
  border-top: 1px solid rgba(60, 80, 70, 0.10);
  background: var(--paper-deep);
}
.footer-inner {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 2rem;
  align-items: start;
}
@media (max-width: 720px) {
  .footer-inner { grid-template-columns: 1fr; }
}
.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}
.footer-brand .brand-icon { width: 36px; height: 36px; }
.footer-brand-name {
  font-weight: 700;
  font-size: 1.08rem;
  color: var(--ink);
}
.footer-brand-by {
  font-size: 0.86rem;
  color: var(--ink-mute);
}
.footer-brand-by a {
  color: var(--moss-deep);
  font-weight: 500;
}
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.4rem;
  font-size: 0.92rem;
  color: var(--ink-soft);
  justify-self: end;
}
@media (max-width: 720px) {
  .footer-links { justify-self: start; }
}
.footer-bottom {
  grid-column: 1 / -1;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(60, 80, 70, 0.08);
  font-size: 0.84rem;
  color: var(--ink-mute);
  text-align: center;
}

/* -----------------------------------------------------------------
   11. Reduce motion
   ----------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}