/* Taiwan Air — official site. Shared by /index.html and /zh-Hant/index.html.
   Sizes follow the Tailwind type scale, spacing the 2/4/8/12/16/24/32/40/48/64/80/96 set,
   radii Tailwind's (4/8/12/16/24/full). */

:root {
  --bg: #f4f8fb;
  --surface: #ffffff;
  --surface-2: #e9f1f6;
  --line: #d5e2ea;
  --ink: #0d1a22;
  --ink-2: #44555f;
  --ink-3: #6a7b85;
  --accent: #0a6f92;
  --accent-ink: #ffffff;
  --sky: #7fd3ea;
  --cta: #0d1a22;
  --cta-ink: #ffffff;
  --nav: rgba(255, 255, 255, 0.72);
  --panel: rgba(244, 248, 251, 0.94);
  --hero-from: #000000;
  --hero-to: #666666;
  --muted-word: rgba(13, 26, 34, 0.28);
  --shadow: 0 1px 2px rgba(13, 26, 34, 0.06), 0 12px 32px rgba(13, 26, 34, 0.08);

  /* Official MOENV AQI band colours, as used in the app. */
  --aqi-good: #009865;
  --aqi-moderate: #fdd83a;
  --aqi-usg: #ff9835;
  --aqi-unhealthy: #ca0034;
  --aqi-very: #670099;
  --aqi-hazardous: #7e0023;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --font: "Manrope", "PingFang TC", "Noto Sans TC", "Heiti TC", system-ui, sans-serif;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #000000;
    --surface: #181818;
    --surface-2: #1f1f1f;
    --line: #313131;
    --ink: #f2f5f7;
    --ink-2: #b9c4ca;
    --ink-3: #8d999f;
    --accent: #6ccbe6;
    --accent-ink: #000000;
    --cta: #ffffff;
    --cta-ink: #000000;
    --nav: rgba(24, 24, 24, 0.72);
    --panel: rgba(0, 0, 0, 0.94);
    --hero-from: #ffffff;
    --hero-to: #9b9b9b;
    --muted-word: rgba(242, 245, 247, 0.3);
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 12px 32px rgba(0, 0, 0, 0.4);
  }
}
:root[data-theme="dark"] {
  --bg: #000000;
  --surface: #181818;
  --surface-2: #1f1f1f;
  --line: #313131;
  --ink: #f2f5f7;
  --ink-2: #b9c4ca;
  --ink-3: #8d999f;
  --accent: #6ccbe6;
  --accent-ink: #000000;
  --cta: #ffffff;
  --cta-ink: #000000;
  --nav: rgba(24, 24, 24, 0.72);
  --panel: rgba(0, 0, 0, 0.94);
  --hero-from: #ffffff;
  --hero-to: #9b9b9b;
  --muted-word: rgba(242, 245, 247, 0.3);
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 12px 32px rgba(0, 0, 0, 0.4);
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 96px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 1rem;
  line-height: 1.5rem;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { display: block; max-width: 100%; height: auto; }
a { color: var(--accent); text-underline-offset: 2px; }
h1, h2, h3 { margin: 0; font-weight: 700; text-wrap: balance; }
p, li, dd { text-wrap: pretty; }
p { margin: 0; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }

.skip {
  position: absolute; left: 16px; top: -64px; z-index: 100;
  padding: 8px 12px; border-radius: 8px;
  background: var(--cta); color: var(--cta-ink); font-weight: 600; text-decoration: none;
}
.skip:focus { top: 16px; }

.wrap { width: 100%; max-width: 1120px; margin: 0 auto; padding: 0 16px; }
@media (min-width: 768px) { .wrap { padding: 0 32px; } }

/* ---------- Navigation ---------- */
.nav {
  position: fixed; top: 12px; left: 50%; transform: translateX(-50%); z-index: 50;
  display: flex; align-items: center; gap: 4px;
  width: max-content; max-width: calc(100% - 24px);
  padding: 4px 4px 4px 12px; border-radius: 9999px;
  background: var(--nav); border: 1px solid var(--line);
  -webkit-backdrop-filter: saturate(160%) blur(16px); backdrop-filter: saturate(160%) blur(16px);
  box-shadow: var(--shadow);
}
.brand { display: flex; align-items: center; gap: 8px; color: var(--ink); text-decoration: none; font-weight: 700; font-size: 0.875rem; line-height: 1.25rem; padding-right: 8px; white-space: nowrap; }
.brand img { width: 24px; height: 24px; border-radius: 6px; }
.nav-links { display: none; align-items: center; gap: 2px; list-style: none; margin: 0; padding: 0; }
.nav-links a {
  display: block; padding: 8px 12px; border-radius: 9999px;
  color: var(--ink-2); text-decoration: none; font-size: 0.875rem; line-height: 1.25rem; font-weight: 600;
  transition: background-color 300ms var(--ease), color 300ms var(--ease);
}
.nav-links a:hover { background: var(--surface-2); color: var(--ink); }
.nav-links a[aria-current="page"] { color: var(--ink); }
.nav-cta {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 8px 12px; border-radius: 9999px;
  background: var(--cta); color: var(--cta-ink); text-decoration: none;
  font-size: 0.875rem; line-height: 1.25rem; font-weight: 600; white-space: nowrap;
  transition: transform 300ms var(--ease), opacity 300ms var(--ease);
}
.nav-cta:hover { transform: translateY(-1px); opacity: 0.9; }
.nav-cta:active { transform: scale(0.98); }
.menu-btn {
  display: inline-grid; place-items: center; width: 36px; height: 36px; margin-left: 4px;
  border: 0; border-radius: 9999px; background: transparent; color: var(--ink); cursor: pointer;
  transition: background-color 300ms var(--ease);
}
.menu-btn:hover { background: var(--surface-2); }
.menu-btn span { display: block; width: 16px; height: 2px; border-radius: 2px; background: currentColor; transition: transform 500ms var(--ease); grid-area: 1 / 1; }
.menu-btn span:first-child { transform: translateY(-4px); }
.menu-btn span:last-child { transform: translateY(4px); }
.menu-btn[aria-expanded="true"] span:first-child { transform: rotate(45deg); }
.menu-btn[aria-expanded="true"] span:last-child { transform: rotate(-45deg); }
@media (min-width: 900px) {
  .nav-links { display: flex; }
  .menu-btn { display: none; }
}

.menu-panel {
  position: fixed; inset: 0; z-index: 40;
  padding: 96px 24px 32px;
  background: var(--panel);
  -webkit-backdrop-filter: blur(24px); backdrop-filter: blur(24px);
  opacity: 0; visibility: hidden;
  transition: opacity 300ms var(--ease), visibility 0s 300ms;
}
.menu-panel.open { opacity: 1; visibility: visible; transition: opacity 300ms var(--ease); }
.menu-panel ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 4px; }
.menu-panel a {
  display: block; padding: 12px 0; color: var(--ink); text-decoration: none;
  font-size: 1.875rem; line-height: 2.25rem; font-weight: 600;
  opacity: 0; transform: translateY(24px);
  transition: opacity 500ms var(--ease), transform 500ms var(--ease);
}
.menu-panel.open a { opacity: 1; transform: none; }
.menu-panel .menu-foot { margin-top: 32px; }
.menu-panel .menu-foot a { font-size: 1rem; line-height: 1.5rem; color: var(--ink-2); }
@media (min-width: 900px) { .menu-panel { display: none; } }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 8px 12px; border-radius: 12px; border: 1px solid transparent;
  font: inherit; font-size: 1rem; line-height: 1.5rem; font-weight: 600; text-decoration: none; cursor: pointer;
  transition: transform 300ms var(--ease), opacity 300ms var(--ease), background-color 300ms var(--ease);
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: scale(0.98); }
.btn-store { background: var(--cta); color: var(--cta-ink); padding: 8px 16px 8px 12px; }
.btn-store:hover { opacity: 0.9; }
.btn-store svg { width: 24px; height: 24px; flex: none; }
.btn-store .lines { display: grid; text-align: left; }
.btn-store .lines small { font-size: 0.75rem; line-height: 1rem; font-weight: 500; opacity: 0.8; }
.btn-ghost { color: var(--ink); border-color: var(--line); background: var(--surface); }
.btn-ghost:hover { background: var(--surface-2); }

/* ---------- Hero ---------- */
.hero { padding: 120px 0 64px; }
@media (min-width: 900px) { .hero { padding: 144px 0 96px; } }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1fr); gap: 48px; align-items: center; }
@media (min-width: 900px) { .hero-grid { grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr); gap: 48px; } }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 4px 12px; border-radius: 9999px; background: var(--surface); border: 1px solid var(--line);
  color: var(--ink-2); font-size: 0.875rem; line-height: 1.25rem; font-weight: 600;
}
.dot { width: 8px; height: 8px; border-radius: 9999px; background: var(--aqi-good); flex: none; }
.hero h1 {
  max-width: 680px; margin-top: 24px;
  font-size: 2.25rem; line-height: 2.5rem; letter-spacing: -0.02em; font-weight: 700;
  background: linear-gradient(90deg, var(--hero-from), var(--hero-to));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
@media (min-width: 640px) { .hero h1 { font-size: 3rem; line-height: 1.05; } }
:lang(zh-Hant) .hero h1 { letter-spacing: 0; line-height: 1.2; }
.hero .lede { max-width: 680px; margin-top: 24px; color: var(--ink-2); font-size: 1.125rem; line-height: 1.75rem; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; align-items: center; }
.proof { display: flex; flex-wrap: wrap; gap: 8px 16px; margin: 24px 0 0; padding: 0; list-style: none; color: var(--ink-3); font-size: 0.875rem; line-height: 1.25rem; }
.proof li { display: inline-flex; align-items: center; gap: 8px; }
.proof svg { width: 16px; height: 16px; color: var(--aqi-good); flex: none; }

.devices { position: relative; display: flex; justify-content: center; align-items: flex-end; gap: 16px; min-height: 360px; }
.phone {
  width: min(50vw, 264px); padding: 8px; border-radius: 24px;
  background: #0d1a22; border: 1px solid var(--line); box-shadow: var(--shadow);
}
.phone img { border-radius: 16px; aspect-ratio: 600 / 1215; object-fit: cover; object-position: top; background: var(--sky); }
.phone.back { width: min(38vw, 216px); margin-bottom: 48px; }
.watch {
  position: absolute; left: 0; bottom: -16px; width: min(30vw, 136px);
  padding: 8px; border-radius: 24px; background: #000; border: 1px solid var(--line); box-shadow: var(--shadow);
}
.watch img { border-radius: 16px; }
@media (min-width: 900px) { .watch { left: -16px; } }

/* AQI band strip */
.bands { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 4px; margin-top: 48px; max-width: 520px; }
.bands span { height: 8px; border-radius: 9999px; }
.b1 { background: var(--aqi-good); } .b2 { background: var(--aqi-moderate); } .b3 { background: var(--aqi-usg); }
.b4 { background: var(--aqi-unhealthy); } .b5 { background: var(--aqi-very); } .b6 { background: var(--aqi-hazardous); }

/* ---------- Sections ---------- */
section { padding: 64px 0; }
@media (min-width: 900px) { section { padding: 96px 0; } }
.kicker { color: var(--accent); font-size: 0.875rem; line-height: 1.25rem; font-weight: 700; letter-spacing: 0.04em; text-transform: uppercase; }
:lang(zh-Hant) .kicker { letter-spacing: 0.08em; }
.section-head { max-width: 680px; }
.section-head h2 { margin-top: 12px; font-size: 1.875rem; line-height: 2.25rem; letter-spacing: -0.01em; }
@media (min-width: 768px) { .section-head h2 { font-size: 2.25rem; line-height: 2.5rem; } }
.section-head p { margin-top: 16px; color: var(--ink-2); font-size: 1.125rem; line-height: 1.75rem; }

.feature-row { display: grid; grid-template-columns: minmax(0, 1fr); gap: 32px; align-items: center; margin-top: 64px; }
@media (min-width: 900px) {
  .feature-row { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 64px; }
  .feature-row.flip .feature-media { order: 2; }
}
.feature-media {
  display: flex; justify-content: center; padding: 32px 16px 0; border-radius: 24px;
  background: var(--surface-2); border: 1px solid var(--line); overflow: hidden;
}
.feature-media .phone { width: min(64vw, 280px); border-radius: 24px 24px 0 0; padding-bottom: 0; }
.feature-media .phone img { border-radius: 16px 16px 0 0; aspect-ratio: 600 / 900; }
.feature-copy h3 { font-size: 1.5rem; line-height: 2rem; }
.feature-copy > p { margin-top: 12px; color: var(--ink-2); font-size: 1.125rem; line-height: 1.75rem; }
.ticks { margin: 24px 0 0; padding: 0; list-style: none; display: grid; gap: 12px; }
.ticks li { display: grid; grid-template-columns: 24px 1fr; gap: 12px; color: var(--ink-2); }
.ticks li strong { color: var(--ink); font-weight: 600; }
.ticks svg { width: 24px; height: 24px; color: var(--accent); }

.cards { display: grid; grid-template-columns: minmax(0, 1fr); gap: 16px; margin-top: 64px; }
@media (min-width: 640px) { .cards { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (min-width: 1000px) { .cards { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
.card {
  padding: 24px; border-radius: 16px; background: var(--surface); border: 1px solid var(--line);
  transition: transform 500ms var(--ease);
}
.card:hover { transform: translateY(-2px); }
.card .ico {
  display: grid; place-items: center; width: 40px; height: 40px; border-radius: 12px;
  background: var(--surface-2); color: var(--accent);
}
.card .ico svg { width: 24px; height: 24px; }
.card h3 { margin-top: 16px; font-size: 1.125rem; line-height: 1.75rem; }
.card p { margin-top: 8px; color: var(--ink-2); }
.card .tag { display: inline-block; margin-top: 12px; padding: 2px 8px; border-radius: 9999px; background: var(--surface-2); color: var(--ink-3); font-size: 0.75rem; line-height: 1rem; font-weight: 600; }

.platforms { display: grid; grid-template-columns: minmax(0, 1fr); gap: 16px; margin-top: 16px; }
@media (min-width: 900px) { .platforms { grid-template-columns: minmax(0, 1fr) minmax(0, 2fr); } }
.platform { border-radius: 16px; background: var(--surface); border: 1px solid var(--line); overflow: hidden; display: flex; flex-direction: column; }
.platform .shot { background: #000; display: grid; place-items: center; padding: 24px; flex: 1; }
.platform .shot img { border-radius: 16px; max-height: 280px; width: auto; }
.platform.vision .shot { padding: 0; }
.platform.vision .shot img { border-radius: 0; max-height: none; width: 100%; aspect-ratio: 16 / 9; object-fit: cover; }
.platform .meta { padding: 24px; }
.platform h3 { font-size: 1.125rem; line-height: 1.75rem; }
.platform p { margin-top: 8px; color: var(--ink-2); }

/* AQI legend */
.legend { display: grid; gap: 8px; margin-top: 48px; grid-template-columns: repeat(2, minmax(0, 1fr)); }
@media (min-width: 768px) { .legend { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
@media (min-width: 1100px) { .legend { grid-template-columns: repeat(6, minmax(0, 1fr)); } }
.legend div { padding: 16px; border-radius: 12px; background: var(--surface); border: 1px solid var(--line); }
.legend i { display: block; height: 4px; border-radius: 9999px; }
.legend b { display: block; margin-top: 12px; font-size: 0.875rem; line-height: 1.25rem; font-weight: 700; }
.legend span { display: block; color: var(--ink-3); font-size: 0.75rem; line-height: 1rem; font-variant-numeric: tabular-nums; }

/* Tagline reveal */
.tagline { padding: 96px 0; }
.tagline p {
  max-width: 900px; font-size: 1.875rem; line-height: 2.25rem; font-weight: 700; letter-spacing: -0.01em;
}
@media (min-width: 640px) { .tagline p { font-size: 2.25rem; line-height: 2.5rem; } }
@media (min-width: 1000px) { .tagline p { font-size: 3rem; line-height: 1.15; } }
:lang(zh-Hant) .tagline p { letter-spacing: 0; line-height: 1.35; }
@media (max-width: 999px) { .tagline p br { display: none; } }
.tagline .w { color: var(--muted-word); transition: color 500ms var(--ease); }
.tagline .w.on { color: var(--ink); }
.tagline .source { margin-top: 32px; max-width: 680px; color: var(--ink-3); font-size: 1rem; line-height: 1.5rem; font-weight: 500; letter-spacing: 0; }

/* Steps */
.steps { display: grid; grid-template-columns: minmax(0, 1fr); gap: 16px; margin: 48px 0 0; padding: 0; list-style: none; counter-reset: step; }
@media (min-width: 900px) { .steps { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
.steps li { padding: 24px; border-radius: 16px; background: var(--surface); border: 1px solid var(--line); }
.steps .n {
  display: grid; place-items: center; width: 32px; height: 32px; border-radius: 9999px;
  background: var(--cta); color: var(--cta-ink); font-weight: 700; font-size: 0.875rem; line-height: 1.25rem;
}
.steps h3 { margin-top: 16px; font-size: 1.125rem; line-height: 1.75rem; }
.steps p { margin-top: 8px; color: var(--ink-2); }

/* FAQ */
.faq { display: grid; gap: 8px; margin-top: 48px; max-width: 820px; }
.faq details { border-radius: 12px; background: var(--surface); border: 1px solid var(--line); }
.faq summary {
  display: flex; justify-content: space-between; align-items: center; gap: 16px;
  padding: 16px 24px; cursor: pointer; list-style: none; font-weight: 600; font-size: 1.125rem; line-height: 1.75rem;
  border-radius: 12px; transition: background-color 300ms var(--ease);
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary:hover { background: var(--surface-2); }
.faq summary svg { width: 20px; height: 20px; flex: none; color: var(--ink-3); transition: transform 500ms var(--ease); }
.faq details[open] summary svg { transform: rotate(45deg); }
.faq .a { padding: 0 24px 24px; color: var(--ink-2); display: grid; gap: 12px; }

/* Contact */
.contact { display: grid; grid-template-columns: minmax(0, 1fr); gap: 16px; margin-top: 48px; }
@media (min-width: 900px) { .contact { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.contact .card:hover { transform: none; }
.path {
  display: flex; flex-wrap: wrap; align-items: center; gap: 4px 8px; margin-top: 16px;
  font-size: 0.875rem; line-height: 1.25rem; font-weight: 600; color: var(--ink);
}
.path span { padding: 4px 8px; border-radius: 8px; background: var(--surface-2); }
.path i { color: var(--ink-3); font-style: normal; }
.note { margin-top: 24px; color: var(--ink-3); font-size: 0.875rem; line-height: 1.25rem; max-width: 820px; }

/* Final CTA */
.final { text-align: center; }
.final .box { padding: 64px 24px; border-radius: 24px; background: var(--surface); border: 1px solid var(--line); }
.final img.icon { width: 80px; height: 80px; border-radius: 16px; margin: 0 auto; box-shadow: var(--shadow); }
.final h2 { margin: 24px auto 0; max-width: 680px; font-size: 1.875rem; line-height: 2.25rem; }
@media (min-width: 768px) { .final h2 { font-size: 2.25rem; line-height: 2.5rem; } }
.final p { margin: 16px auto 0; max-width: 560px; color: var(--ink-2); font-size: 1.125rem; line-height: 1.75rem; }
.final .hero-actions { justify-content: center; }

/* Footer */
footer { padding: 48px 0 64px; border-top: 1px solid var(--line); color: var(--ink-3); font-size: 0.875rem; line-height: 1.25rem; }
.foot { display: grid; grid-template-columns: minmax(0, 1fr); gap: 32px; }
@media (min-width: 768px) { .foot { grid-template-columns: minmax(0, 2fr) minmax(0, 1fr) minmax(0, 1fr); } }
.foot h2 { font-size: 0.875rem; line-height: 1.25rem; color: var(--ink); font-weight: 700; }
.foot ul { list-style: none; margin: 12px 0 0; padding: 0; display: grid; gap: 8px; }
.foot a { color: var(--ink-2); text-decoration: none; }
.foot a:hover { color: var(--ink); text-decoration: underline; }
.foot p + p { margin-top: 8px; }
.foot .foot-note { margin-top: 12px; }

/* Reveal on scroll */
.reveal { opacity: 0; transform: translateY(32px); transition: opacity 700ms var(--ease), transform 700ms var(--ease); }
.reveal.in { opacity: 1; transform: none; }
.no-js .reveal { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { transform: none; transition: opacity 300ms var(--ease); }
  .menu-panel a { transform: none; }
  .btn:hover, .nav-cta:hover, .card:hover { transform: none; }
  .menu-btn span, .faq summary svg { transition: none; }
}