:root {
  --blue: #208aef;
  --blue-dark: #1568c4;
  --bg: #f4f8fc;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --radius: 16px;
  --shadow: 0 12px 40px rgba(32, 138, 239, 0.12);
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  --font-zh: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", var(--font);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

body[lang="zh"] {
  font-family: var(--font-zh);
}

a {
  color: var(--blue);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

img {
  max-width: 100%;
  height: auto;
}

.container {
  width: min(1080px, 92vw);
  margin-inline: auto;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(244, 248, 252, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text);
  text-decoration: none;
}

.brand:hover {
  text-decoration: none;
}

.brand img {
  width: 36px;
  height: 36px;
  border-radius: 9px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.nav {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.nav a {
  color: var(--muted);
  font-size: 0.95rem;
  font-weight: 500;
}

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

.lang-switch {
  display: flex;
  gap: 0.35rem;
  font-size: 0.9rem;
}

.lang-switch a {
  padding: 0.25rem 0.5rem;
  border-radius: 6px;
}

.lang-switch a[aria-current="page"] {
  background: var(--surface);
  color: var(--blue);
  font-weight: 600;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

/* Hero */
.hero {
  padding: 4rem 0 3.5rem;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.5rem;
  align-items: center;
}

@media (min-width: 840px) {
  .hero-grid {
    grid-template-columns: 1.1fr 0.9fr;
  }
}

.eyebrow {
  display: inline-block;
  margin: 0 0 0.75rem;
  padding: 0.35rem 0.75rem;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--blue);
  background: rgba(32, 138, 239, 0.1);
  border-radius: 999px;
}

.hero h1 {
  margin: 0 0 1rem;
  font-size: clamp(2rem, 5vw, 2.75rem);
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.hero-lead {
  margin: 0 0 1.75rem;
  font-size: 1.125rem;
  color: var(--muted);
  max-width: 36ch;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1.35rem;
  font-size: 1rem;
  font-weight: 600;
  border-radius: 12px;
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--blue);
  color: #fff;
  box-shadow: var(--shadow);
}

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

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
}

.hero-visual {
  display: flex;
  justify-content: center;
  margin: 0;
}

.phone-mock {
  width: min(302px, 72vw);
  margin: 0;
  border-radius: 28px;
  overflow: hidden;
  box-shadow: var(--shadow), 0 0 0 1px rgba(15, 23, 42, 0.06);
  background: var(--surface);
}

.phone-mock img {
  display: block;
  width: 100%;
  height: auto;
  vertical-align: middle;
}

/* Features */
.section {
  padding: 3.5rem 0;
}

.section-title {
  margin: 0 0 0.5rem;
  font-size: 1.75rem;
  letter-spacing: -0.02em;
}

.section-sub {
  margin: 0 0 2rem;
  color: var(--muted);
  max-width: 52ch;
}

.features {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem;
}

@media (min-width: 640px) {
  .features {
    grid-template-columns: repeat(3, 1fr);
  }
}

.feature-card {
  padding: 1.5rem;
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: box-shadow 0.2s ease;
}

.feature-card:hover {
  box-shadow: 0 8px 24px rgba(15, 23, 42, 0.06);
}

.feature-icon {
  font-size: 1.75rem;
  margin-bottom: 0.75rem;
}

.feature-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.1rem;
}

.feature-card p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--muted);
}

/* FAQ */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.faq-item {
  padding: 1.25rem 1.5rem;
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.faq-item h3 {
  margin: 0 0 0.35rem;
  font-size: 1rem;
}

.faq-item p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--muted);
}

/* Footer */
.site-footer {
  margin-top: 2rem;
  padding: 2rem 0 2.5rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.9rem;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 1rem;
  align-items: center;
}

.footer-links {
  display: flex;
  gap: 1.25rem;
}