:root {
  --bg: #f5f5f7;
  --bg-tint: #eef1f6;
  --surface: #ffffff;
  --ink: #1d1d1f;
  --ink-soft: #4b4b51;
  --ink-mute: #86868b;
  --blue: #4a90ff;
  --blue-deep: #2f6fe0;
  --blue-soft: #dce8ff;
  --line: #e3e3e8;
  --radius: 20px;
  --shadow: 0 12px 40px rgba(40, 60, 110, 0.10);
  --shadow-soft: 0 4px 18px rgba(40, 60, 110, 0.07);
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
    "Helvetica Neue", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; scroll-padding-top: 80px; }

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: inherit; text-decoration: none; }

/* ===== Nav ===== */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 24px;
  padding: 14px clamp(20px, 5vw, 64px);
  background: rgba(245, 245, 247, 0.78);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}
.nav__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 19px;
  letter-spacing: -0.01em;
}
.nav__brand img { border-radius: 8px; }
.nav__links {
  display: flex;
  gap: 28px;
  margin-left: auto;
  font-size: 15px;
  color: var(--ink-soft);
}
.nav__links a:hover { color: var(--ink); }
.nav__right { display: flex; align-items: center; gap: 14px; margin-left: 24px; }
/* Segmented language switch — fixed width, no layout shift on toggle */
.lang-switch {
  position: relative;
  display: inline-flex;
  align-items: center;
  padding: 3px;
  border-radius: 980px;
  background: rgba(0, 0, 0, 0.05);
  border: 1px solid var(--line);
}
.lang-switch__thumb {
  position: absolute;
  top: 3px;
  bottom: 3px;
  left: 3px;
  width: 42px;
  border-radius: 980px;
  background: var(--surface);
  box-shadow: var(--shadow-soft);
  transition: transform 0.22s cubic-bezier(0.4, 0, 0.2, 1);
}
.lang-switch[data-active="zh"] .lang-switch__thumb { transform: translateX(42px); }
.lang-switch__opt {
  position: relative;
  z-index: 1;
  width: 42px;
  font-family: inherit;
  font-size: 13px;
  font-weight: 500;
  color: var(--ink-mute);
  background: transparent;
  border: 0;
  border-radius: 980px;
  padding: 6px 0;
  cursor: pointer;
  line-height: 1;
  transition: color 0.18s ease;
}
.lang-switch__opt:hover { color: var(--ink-soft); }
.lang-switch__opt[aria-pressed="true"] { color: var(--ink); }

@media (max-width: 720px) {
  .nav__links { display: none; }
  .nav__right { margin-left: auto; }
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 500;
  font-size: 16px;
  border-radius: 980px;
  padding: 13px 26px;
  transition: transform 0.12s ease, box-shadow 0.2s ease, background 0.2s ease;
  white-space: nowrap;
}
.btn--small { font-size: 14px; padding: 8px 18px; min-width: 104px; background: var(--ink); color: #fff; }
.btn--small:hover { background: #000; }
.btn--primary {
  background: linear-gradient(180deg, var(--blue) 0%, var(--blue-deep) 100%);
  color: #fff;
  box-shadow: 0 8px 22px rgba(74, 144, 255, 0.35);
}
.btn--primary:hover { transform: translateY(-1px); box-shadow: 0 12px 28px rgba(74, 144, 255, 0.42); }
.btn--block { display: flex; width: 100%; margin-top: 6px; }

/* ===== Hero ===== */
.hero {
  position: relative;
  text-align: center;
  padding: clamp(64px, 11vw, 128px) 20px clamp(48px, 7vw, 80px);
  overflow: hidden;
}
.hero__glow {
  position: absolute;
  top: -120px;
  left: 50%;
  transform: translateX(-50%);
  width: 760px;
  max-width: 120vw;
  height: 560px;
  background: radial-gradient(ellipse at center, rgba(74, 144, 255, 0.22), transparent 62%);
  filter: blur(20px);
  z-index: 0;
}
.hero > *:not(.hero__glow) { position: relative; z-index: 1; }
.hero__icon {
  border-radius: 30px;
  box-shadow: var(--shadow);
  margin-bottom: 28px;
  animation: floaty 6s ease-in-out infinite;
}
@keyframes floaty {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-9px); }
}
.hero__title {
  font-size: clamp(48px, 8vw, 80px);
  font-weight: 700;
  letter-spacing: -0.03em;
}
.hero__tagline {
  font-size: clamp(20px, 3vw, 28px);
  font-weight: 500;
  color: var(--ink);
  max-width: 660px;
  margin: 16px auto 0;
  letter-spacing: -0.01em;
}
.hero__sub {
  font-size: clamp(15px, 2vw, 18px);
  color: var(--ink-soft);
  max-width: 600px;
  margin: 18px auto 0;
}
.hero__cta { margin-top: 34px; display: flex; flex-direction: column; align-items: center; gap: 14px; }
.hero__meta { font-size: 13px; color: var(--ink-mute); }

/* ===== Trust strip ===== */
.strip {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: clamp(28px, 8vw, 88px);
  padding: 28px 20px 8px;
  max-width: 980px;
  margin: 0 auto;
}
.strip__item { text-align: center; }
.strip__item strong {
  display: block;
  font-size: clamp(34px, 5vw, 46px);
  font-weight: 700;
  color: var(--blue-deep);
  letter-spacing: -0.02em;
}
.strip__item span { font-size: 14px; color: var(--ink-mute); }

/* ===== Sections ===== */
.section {
  max-width: 1080px;
  margin: 0 auto;
  padding: clamp(64px, 10vw, 112px) clamp(20px, 5vw, 48px);
}
.section--tint {
  max-width: none;
  background: var(--bg-tint);
}
.section--tint > * { max-width: 1080px; margin-left: auto; margin-right: auto; }
.section__title {
  font-size: clamp(30px, 4.5vw, 46px);
  font-weight: 700;
  letter-spacing: -0.02em;
  text-align: center;
}
.section__lead {
  font-size: clamp(16px, 2vw, 19px);
  color: var(--ink-soft);
  text-align: center;
  max-width: 600px;
  margin: 16px auto 0;
}

/* ===== Feature grid ===== */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 22px;
  margin-top: 52px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 32px 28px;
  box-shadow: var(--shadow-soft);
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.card__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 14px;
  background: var(--blue-soft);
  color: var(--blue-deep);
  font-size: 22px;
  margin-bottom: 18px;
}
.card h3 { font-size: 19px; font-weight: 600; letter-spacing: -0.01em; }
.card p { margin-top: 10px; font-size: 15px; color: var(--ink-soft); }

/* ===== Hosts ===== */
.hosts {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-top: 48px;
}
.hosts li {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 11px 22px;
  font-size: 15px;
  font-weight: 500;
  color: var(--ink-soft);
  box-shadow: var(--shadow-soft);
}

/* ===== Showcase ===== */
.shots {
  display: flex;
  gap: 22px;
  margin-top: 48px;
  padding: 4px 2px 20px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.shot {
  flex: none;
  width: min(560px, 86vw);
  margin: 0;
}
.shot img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 18px;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  background: var(--surface);
}
.shots::-webkit-scrollbar { height: 8px; }
.shots::-webkit-scrollbar-thumb {
  background: rgba(40, 60, 110, 0.18);
  border-radius: 999px;
}

/* ===== Privacy pillars ===== */
.pillars {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 52px;
}
/* 3 cards on the first row; the 4th spans the full width beneath them */
.pillar:last-child {
  grid-column: 1 / -1;
  display: flex;
  flex-direction: column;
  justify-content: center;
}
@media (max-width: 860px) {
  .pillars { grid-template-columns: repeat(2, 1fr); }
  .pillar:last-child { grid-column: 1 / -1; }
}
@media (max-width: 560px) {
  .pillars { grid-template-columns: 1fr; }
}
.pillar {
  padding: 28px 26px;
  border-left: 3px solid var(--blue);
  background: var(--surface);
  border-radius: 0 var(--radius) var(--radius) 0;
  box-shadow: var(--shadow-soft);
}
.pillar h3 { font-size: 18px; font-weight: 600; }
.pillar p { margin-top: 8px; font-size: 15px; color: var(--ink-soft); }
.pillar code {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 13px;
  background: var(--bg-tint);
  padding: 1px 6px;
  border-radius: 5px;
}

/* ===== Legal / privacy page ===== */
.legal {
  max-width: 760px;
  margin: 0 auto;
  padding: clamp(48px, 8vw, 88px) clamp(20px, 5vw, 40px) 72px;
}
.legal__title {
  font-size: clamp(32px, 5vw, 46px);
  font-weight: 700;
  letter-spacing: -0.02em;
}
.legal__updated { margin-top: 10px; color: var(--ink-mute); font-size: 14px; }
.legal__intro {
  margin-top: 24px;
  font-size: 18px;
  color: var(--ink-soft);
}
.legal h2 {
  margin-top: 44px;
  font-size: 22px;
  font-weight: 600;
  letter-spacing: -0.01em;
}
.legal p { margin-top: 12px; color: var(--ink-soft); }
.legal ul { margin: 12px 0 0 20px; color: var(--ink-soft); }
.legal li { margin-top: 8px; }
.legal a { color: var(--blue-deep); }
.legal a:hover { text-decoration: underline; }
.legal code {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 13px;
  background: var(--bg-tint);
  padding: 1px 6px;
  border-radius: 5px;
}
.legal__back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 28px;
  font-size: 15px;
  color: var(--ink-soft);
}
.legal__back:hover { color: var(--ink); }

/* ===== Support page ===== */
.contact-card {
  margin-top: 28px;
  padding: 32px 30px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
}
.contact-card h2 { margin-top: 0; font-size: 20px; font-weight: 600; }
.contact-card p { margin-top: 8px; color: var(--ink-soft); }
.contact-card__email { color: var(--blue-deep); font-weight: 500; }
.contact-card__email:hover { text-decoration: underline; }
.contact-card__hint { margin-top: 14px; font-size: 14px; color: var(--ink-mute); }
.support-q { font-size: 18px; }

/* ===== Footer ===== */
.footer {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
  padding: 56px 20px 64px;
  border-top: 1px solid var(--line);
  text-align: center;
}
.footer__brand {
  display: flex;
  align-items: center;
  gap: 9px;
  font-weight: 600;
  font-size: 17px;
}
.footer__brand img { border-radius: 7px; }
.footer__links { display: flex; gap: 26px; font-size: 14px; color: var(--ink-soft); }
.footer__links a:hover { color: var(--ink); }
.footer__copy { font-size: 13px; color: var(--ink-mute); }