:root {
  --bg: #f7f8f5;
  --surface: #ffffff;
  --surface-soft: #edf5eb;
  --text: #24303c;
  --muted: #66727e;
  --line: #dce4dc;
  --green: #43a047;
  --green-dark: #287432;
  --shadow: 0 18px 45px rgba(36, 48, 60, 0.1);
  --radius: 8px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Noto Sans TC", "Microsoft JhengHei", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
}

a {
  color: inherit;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(247, 248, 245, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(14px);
}

.topbar-inner,
.site-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
}

.topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 12px 0;
}

.site-shell {
  padding: 34px 0 28px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  min-width: 210px;
}

.brand-icon,
.download-icon {
  width: 42px;
  height: 42px;
  border-radius: 7px;
  box-shadow: 0 8px 20px rgba(36, 48, 60, 0.14);
}

.brand strong {
  display: block;
  font-size: 1.06rem;
  letter-spacing: 0;
}

.brand small {
  display: block;
  color: var(--muted);
  font-size: 0.82rem;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 24px;
}

.section-tabs {
  display: flex;
  align-items: center;
  gap: 24px;
}

.language-picker {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 750;
}

.language-picker select {
  min-height: 34px;
  padding: 0 30px 0 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  color: var(--text);
  font: inherit;
  cursor: pointer;
}

.tab-button {
  min-height: 38px;
  padding: 0 4px;
  border: 0;
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

.tab-button.is-active {
  color: var(--green-dark);
  box-shadow: inset 0 -3px 0 var(--green);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 36px;
  align-items: end;
  padding: 30px 0 38px;
  border-bottom: 1px solid var(--line);
}

.hero-copy {
  max-width: 770px;
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--green-dark);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 740px;
  margin: 0;
  font-size: clamp(2.15rem, 4.5vw, 4.35rem);
  line-height: 1.08;
  letter-spacing: 0;
}

.hero p:last-child {
  max-width: 720px;
  margin: 18px 0 0;
  color: var(--muted);
  font-size: 1.08rem;
}

.hero-card {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: 0 14px 32px rgba(36, 48, 60, 0.1);
}

.hero-card img {
  width: 70px;
  height: 70px;
  border-radius: 8px;
}

.hero-card strong,
.hero-card span {
  display: block;
}

.hero-card strong {
  font-size: 1.05rem;
}

.hero-card span {
  color: var(--muted);
}

.layout {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: 56px;
  align-items: start;
  margin-top: 40px;
}

.sidebar {
  position: sticky;
  top: 88px;
}

.sidebar-heading {
  padding-bottom: 14px;
  border-bottom: 1px solid var(--line);
}

.sidebar-heading span {
  display: block;
  font-weight: 800;
  font-size: 1.05rem;
}

.sidebar-heading small {
  color: var(--muted);
}

.side-nav {
  display: grid;
  gap: 4px;
  margin-top: 14px;
}

.side-link {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  min-height: 42px;
  padding: 0 0 0 12px;
  border: 0;
  border-left: 3px solid transparent;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-weight: 750;
  text-align: left;
  cursor: pointer;
}

.side-link::after {
  content: "";
  width: 7px;
  height: 7px;
  border-top: 2px solid currentColor;
  border-right: 2px solid currentColor;
  transform: rotate(45deg);
  opacity: 0.35;
}

.side-link:hover,
.side-link.is-active {
  border-left-color: var(--green);
  color: var(--green-dark);
  background: rgba(237, 245, 235, 0.75);
}

.content-panel {
  min-width: 0;
}

.content-heading {
  max-width: 820px;
  margin-bottom: 18px;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--line);
}

h2 {
  margin: 0;
  line-height: 1.2;
  letter-spacing: 0;
}

.content-heading h2 {
  font-size: clamp(1.85rem, 3vw, 2.85rem);
}

iframe {
  width: 100%;
  min-height: 420px;
  border: 0;
  background: transparent;
  overflow: hidden;
}

.download-band {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  margin-top: 56px;
  padding: 22px 24px;
  background: rgba(255, 255, 255, 0.94);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.download-copy {
  display: flex;
  align-items: center;
  gap: 16px;
}

.download-copy p:last-child {
  margin: 7px 0 0;
  color: var(--muted);
}

.play-badge {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 184px;
  min-height: 58px;
  padding: 8px 16px 8px 12px;
  border-radius: 7px;
  background: #111827;
  color: white;
  text-decoration: none;
  box-shadow: 0 12px 24px rgba(17, 24, 39, 0.22);
}

.play-badge svg {
  width: 30px;
  height: 34px;
  flex: 0 0 auto;
}

.play-badge span,
.play-badge em,
.play-badge strong {
  display: block;
}

.play-badge em {
  font-size: 0.66rem;
  font-style: normal;
  letter-spacing: 0.08em;
  line-height: 1.1;
}

.play-badge strong {
  font-size: 1.25rem;
  line-height: 1.1;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 4px 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.site-footer a {
  text-decoration: none;
}

@media (max-width: 820px) {
  .topbar-inner,
  .download-band,
  .site-footer {
    align-items: stretch;
    flex-direction: column;
  }

  .site-shell,
  .topbar-inner {
    width: min(100% - 20px, 1180px);
  }

  .header-actions {
    align-items: flex-start;
    flex-direction: column;
    gap: 12px;
  }

  .section-tabs {
    justify-content: flex-start;
  }

  .hero {
    grid-template-columns: 1fr;
    gap: 22px;
    padding-top: 24px;
  }

  .layout {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .sidebar {
    position: static;
  }

  .side-nav {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .download-copy {
    align-items: flex-start;
  }

  .play-badge {
    width: 100%;
  }
}

@media (max-width: 480px) {
  .side-nav {
    grid-template-columns: 1fr;
  }
}