/* ============================================================
   site.css — Too Apps shared stylesheet
   Sections: Reset · Tokens · Layout · Header · Hero ·
             Apps · Why · FAQ · CTA Banner · Footer · Utilities
   ============================================================ */

/* ── Reset ─────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { background: none; border: none; cursor: pointer; font: inherit; }
[hidden] { display: none !important; }

/* ── Design Tokens ──────────────────────────────────────────── */
:root {
  /* Brand */
  --blue:        #0A84FF;
  --blue-dark:   #0060DF;
  --teal:        #30D158;
  --indigo:      #5E5CE6;
  --orange:      #FF9F0A;
  --pink:        #FF375F;

  /* Neutral */
  --text-primary:   #1C1C1E;
  --text-secondary: #6E6E73;
  --text-tertiary:  #AEAEB2;
  --surface:        #FFFFFF;
  --surface-raised: #F2F2F7;
  --border:         #D1D1D6;
  --border-subtle:  #E5E5EA;

  /* Typography */
  --font-base: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Fira Code", monospace;

  --size-xs:   0.75rem;   /* 12 */
  --size-sm:   0.875rem;  /* 14 */
  --size-base: 1rem;      /* 16 */
  --size-md:   1.125rem;  /* 18 */
  --size-lg:   1.25rem;   /* 20 */
  --size-xl:   1.5rem;    /* 24 */
  --size-2xl:  2rem;      /* 32 */
  --size-3xl:  2.5rem;    /* 40 */
  --size-4xl:  3.5rem;    /* 56 */

  /* Spacing */
  --sp-1: 0.25rem;
  --sp-2: 0.5rem;
  --sp-3: 0.75rem;
  --sp-4: 1rem;
  --sp-6: 1.5rem;
  --sp-8: 2rem;
  --sp-12: 3rem;
  --sp-16: 4rem;
  --sp-20: 5rem;
  --sp-24: 6rem;

  /* Radii */
  --radius-sm:  6px;
  --radius-md:  12px;
  --radius-lg:  20px;
  --radius-xl:  28px;
  --radius-full: 999px;

  /* Shadows */
  --shadow-sm:  0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.04);
  --shadow-md:  0 4px 16px rgba(0,0,0,.10), 0 2px 4px rgba(0,0,0,.06);
  --shadow-lg:  0 10px 40px rgba(0,0,0,.12), 0 4px 8px rgba(0,0,0,.06);

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --dur-fast: 150ms;
  --dur-mid:  250ms;
}

/* ── Dark Mode ──────────────────────────────────────────────── */
@media (prefers-color-scheme: dark) {
  :root {
    --text-primary:   #F5F5F7;
    --text-secondary: #A1A1A6;
    --text-tertiary:  #636366;
    --surface:        #1C1C1E;
    --surface-raised: #2C2C2E;
    --border:         #38383A;
    --border-subtle:  #2C2C2E;
  }
}

/* ── Base Typography ────────────────────────────────────────── */
body {
  font-family: var(--font-base);
  font-size: var(--size-base);
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--surface);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 {
  line-height: 1.2;
  letter-spacing: -0.02em;
  font-weight: 700;
}

p { max-width: 65ch; }

/* ── Layout ─────────────────────────────────────────────────── */
.container {
  width: 100%;
  max-width: 1120px;
  margin-inline: auto;
  padding-inline: var(--sp-6);
}

section { padding-block: var(--sp-20); }

/* ── Language Toggle ────────────────────────────────────────── */
/* Elements carry data-zh and data-en text; JS swaps innerHTML */
[data-lang="en"] [data-en] { }  /* keep visible */

/* ── HEADER ─────────────────────────────────────────────────── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.82);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border-subtle);
}

@media (prefers-color-scheme: dark) {
  .site-header { background: rgba(28,28,30,0.82); }
}

.header-inner {
  display: flex;
  align-items: center;
  gap: var(--sp-6);
  height: 60px;
}

.logo {
  display: flex;
  align-items: baseline;
  gap: 2px;
  text-decoration: none;
  flex-shrink: 0;
}

.logo-mark {
  font-size: var(--size-lg);
  font-weight: 800;
  color: var(--blue);
  letter-spacing: -0.04em;
}

.logo-sub {
  font-size: var(--size-sm);
  font-weight: 600;
  color: var(--text-secondary);
}

.site-nav {
  display: flex;
  gap: var(--sp-6);
  margin-inline-start: auto;
}

.site-nav a {
  font-size: var(--size-sm);
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--dur-fast);
}

.site-nav a:hover { color: var(--text-primary); }

.lang-toggle {
  margin-inline-start: var(--sp-4);
  font-size: var(--size-sm);
  font-weight: 600;
  color: var(--blue);
  padding: var(--sp-1) var(--sp-3);
  border: 1.5px solid var(--blue);
  border-radius: var(--radius-full);
  transition: background var(--dur-fast), color var(--dur-fast);
}

.lang-toggle:hover {
  background: var(--blue);
  color: #fff;
}

/* Show/hide label based on current lang */
[data-lang="zh"] .lang-zh { display: none; }
[data-lang="en"] .lang-en { display: none; }

/* ── HERO ───────────────────────────────────────────────────── */
.hero {
  padding-block: var(--sp-24) var(--sp-20);
  background: linear-gradient(160deg, var(--surface) 55%, color-mix(in srgb, var(--blue) 5%, var(--surface)) 100%);
  overflow: hidden;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: var(--sp-12);
}

.hero-eyebrow {
  font-size: var(--size-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--blue);
  margin-bottom: var(--sp-4);
}

.hero-text h1 {
  font-size: clamp(var(--size-3xl), 5vw, var(--size-4xl));
  margin-bottom: var(--sp-6);
}

.hero-accent { color: var(--blue); }

.hero-desc {
  font-size: var(--size-md);
  color: var(--text-secondary);
  margin-bottom: var(--sp-8);
  max-width: 44ch;
}

.cta-group {
  display: flex;
  gap: var(--sp-4);
  flex-wrap: wrap;
  align-items: center;
}

/* ── Buttons ────────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--size-sm);
  font-weight: 600;
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius-full);
  transition: transform var(--dur-fast) var(--ease-out),
              box-shadow var(--dur-fast) var(--ease-out),
              background var(--dur-fast);
  white-space: nowrap;
}

.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

.btn-primary {
  background: var(--blue);
  color: #fff;
  box-shadow: 0 2px 8px rgba(10,132,255,.35);
}

.btn-primary:hover {
  background: var(--blue-dark);
  box-shadow: 0 4px 16px rgba(10,132,255,.45);
}

.btn-store {
  background: var(--text-primary);
  color: var(--surface);
  box-shadow: var(--shadow-sm);
}

.btn-store:hover { box-shadow: var(--shadow-md); }

.btn-store--sm {
  font-size: var(--size-xs);
  padding: 0.4rem 0.85rem;
}

.btn-card-detail {
  font-size: var(--size-xs);
  color: var(--blue);
  padding: 0.4rem 0.85rem;
  border: 1.5px solid var(--blue);
  border-radius: var(--radius-full);
}

.btn-card-detail:hover { background: var(--blue); color: #fff; }

.btn-large {
  font-size: var(--size-base);
  padding: 0.85rem 2rem;
}

.icon-apple { width: 16px; height: 16px; fill: currentColor; flex-shrink: 0; }
.btn-large .icon-apple { width: 20px; height: 20px; }

.app-card-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-3);
}

.app-card-buttons {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: var(--sp-2);
}

.qr-download {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  color: var(--text-tertiary);
  font-size: 10px;
  line-height: 1.2;
  transition: transform var(--dur-fast) var(--ease-out), color var(--dur-fast);
}

.qr-download:hover {
  color: var(--text-secondary);
  transform: translateY(-1px);
}

.qr-download-image {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.qr-download-code {
  display: block;
  background: #fff;
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.qr-download--card .qr-download-code {
  width: 44px;
  height: 44px;
}

.qr-download--hero {
  font-size: var(--size-xs);
}

.qr-download--hero .qr-download-code {
  width: 82px;
  height: 82px;
}

/* ── Hero Visual ────────────────────────────────────────────── */
.hero-visual {
  display: flex;
  justify-content: center;
}

.hero-device {
  width: 260px;
  height: 520px;
  background: var(--surface-raised);
  border-radius: 40px;
  border: 6px solid var(--border);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.device-screen {
  width: 100%;
  height: 100%;
  background: linear-gradient(160deg, #F2F2F7 0%, #E5E5EA 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--sp-8);
}

@media (prefers-color-scheme: dark) {
  .device-screen { background: linear-gradient(160deg, #1C1C1E 0%, #2C2C2E 100%); }
}

.app-icon-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-4);
}

.app-icon-link {
  display: block;
  border-radius: 18px;
}

.app-icon-link:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}

/* ── App Icons (reusable color swatches) ────────────────────── */
.app-icon {
  width: 80px;
  height: 80px;
  border-radius: 18px;
  box-shadow: var(--shadow-md);
}

.app-icon-grid .app-icon[src] {
  object-fit: cover;
  display: block;
  overflow: hidden;
}

.app-card-icon {
  width: 64px;
  height: 64px;
  border-radius: 14px;
  box-shadow: var(--shadow-sm);
  flex-shrink: 0;
  overflow: hidden;
}

.app-card-icon img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.app-icon--teal   { background: linear-gradient(135deg, #30D158, #34C759); }
.app-icon--indigo { background: linear-gradient(135deg, #5E5CE6, #7C7AE9); }
.app-icon--orange { background: linear-gradient(135deg, #FF9F0A, #FFCC00); }
.app-icon--pink   { background: linear-gradient(135deg, #FF375F, #FF6482); }

/* ── APPS SECTION ───────────────────────────────────────────── */
.section-apps { background: var(--surface-raised); }

.section-title {
  font-size: clamp(var(--size-2xl), 3.5vw, var(--size-3xl));
  text-align: center;
  margin-bottom: var(--sp-4);
}

.section-sub {
  text-align: center;
  color: var(--text-secondary);
  margin-bottom: var(--sp-12);
  font-size: var(--size-md);
  max-width: none;
}

.app-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--sp-6);
}

.app-card {
  background: var(--surface);
  border-radius: var(--radius-xl);
  padding: var(--sp-6);
  display: flex;
  flex-direction: column;
  gap: var(--sp-4);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-subtle);
  transition: box-shadow var(--dur-mid) var(--ease-out),
              transform var(--dur-mid) var(--ease-out);
  cursor: pointer;
}

.app-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-3px);
}

.app-card-body {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  flex: 1;
}

.app-card-name {
  font-size: var(--size-lg);
  font-weight: 700;
}

.app-card-tag {
  font-size: var(--size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-tertiary);
}

.app-card-desc {
  font-size: var(--size-sm);
  color: var(--text-secondary);
  flex: 1;
}

.app-card .btn { align-self: flex-start; }

.app-card:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 3px;
}

/* ── WHY SECTION ────────────────────────────────────────────── */
.section-why { background: var(--surface); }

.value-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--sp-6);
  margin-top: var(--sp-12);
}

.value-card {
  background: var(--surface-raised);
  border-radius: var(--radius-lg);
  padding: var(--sp-6);
  border: 1px solid var(--border-subtle);
  transition: box-shadow var(--dur-mid) var(--ease-out);
}

.value-card:hover { box-shadow: var(--shadow-md); }

.value-icon {
  font-size: 2rem;
  margin-bottom: var(--sp-4);
  line-height: 1;
}

.value-title {
  font-size: var(--size-md);
  font-weight: 700;
  margin-bottom: var(--sp-2);
}

.value-desc {
  font-size: var(--size-sm);
  color: var(--text-secondary);
  max-width: 38ch;
}

/* ── FAQ SECTION ────────────────────────────────────────────── */
.section-faq { background: var(--surface-raised); }

.faq-container { max-width: 760px; }

.faq-list { margin-top: var(--sp-12); }

.faq-item {
  border-bottom: 1px solid var(--border-subtle);
}

.faq-item:first-child { border-top: 1px solid var(--border-subtle); }

.faq-question {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--sp-6) 0;
  font-size: var(--size-base);
  font-weight: 600;
  text-align: left;
  color: var(--text-primary);
  gap: var(--sp-4);
}

.faq-question:hover { color: var(--blue); }

.faq-chevron {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  stroke: currentColor;
  stroke-width: 2;
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform var(--dur-mid) var(--ease-out);
}

.faq-question[aria-expanded="true"] .faq-chevron {
  transform: rotate(180deg);
}

.faq-answer {
  padding-bottom: var(--sp-6);
}

.faq-answer p {
  font-size: var(--size-sm);
  color: var(--text-secondary);
}

/* ── CTA BANNER ─────────────────────────────────────────────── */
.section-cta-banner {
  background: linear-gradient(135deg, var(--blue) 0%, var(--indigo) 100%);
  padding-block: var(--sp-20);
  color: #fff;
}

.cta-banner-inner {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-6);
}

.cta-banner-inner h2 {
  font-size: clamp(var(--size-2xl), 4vw, var(--size-3xl));
  color: #fff;
}

.cta-banner-inner p {
  font-size: var(--size-md);
  opacity: 0.85;
  max-width: none;
}

.cta-banner-inner .btn-primary {
  background: #fff;
  color: var(--blue);
  box-shadow: 0 4px 24px rgba(0,0,0,.2);
}

.cta-banner-inner .btn-primary:hover {
  background: #f0f0f0;
}

/* ── FOOTER ─────────────────────────────────────────────────── */
.site-footer {
  background: var(--surface-raised);
  border-top: 1px solid var(--border-subtle);
  padding-block: var(--sp-12);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--sp-6);
}

.footer-brand { flex: 1; min-width: 160px; }

.footer-tagline {
  font-size: var(--size-xs);
  color: var(--text-tertiary);
  margin-top: var(--sp-1);
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-4) var(--sp-6);
  font-size: var(--size-sm);
  color: var(--text-secondary);
}

.footer-nav a:hover { color: var(--blue); }

.footer-legal {
  width: 100%;
  font-size: var(--size-xs);
  color: var(--text-tertiary);
  max-width: none;
}

/* ── Responsive ─────────────────────────────────────────────── */
@media (max-width: 768px) {
  section { padding-block: var(--sp-16); }

  .hero { padding-block: var(--sp-16) var(--sp-12); }

  .hero-inner {
    grid-template-columns: 1fr;
    gap: var(--sp-12);
  }

  .hero-visual { order: -1; }

  .hero-device {
    width: 200px;
    height: 400px;
  }

  .app-icon { width: 60px; height: 60px; }

  .site-nav { display: none; }

  .footer-inner { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 480px) {
  .container { padding-inline: var(--sp-4); }

  .cta-group { flex-direction: column; align-items: flex-start; }

  .app-grid { grid-template-columns: 1fr; }

  .qr-download--hero .qr-download-code {
    width: 72px;
    height: 72px;
  }

  .value-grid { grid-template-columns: 1fr; }
}

/* ── Accessibility ──────────────────────────────────────────── */
:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
}