:root {
  --bg: #f5f5f7;
  --card-bg: #ffffff;
  --text: #1d1d1f;
  --text-secondary: #6e6e73;
  --accent: #007aff;
  --accent-dark: #0060df;
  --border: rgba(0, 0, 0, 0.06);
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
  --radius: 20px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI",
    Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

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

section {
  scroll-margin-top: 84px;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(245, 245, 247, 0.8);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding-top: 16px;
  padding-bottom: 16px;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
}

.main-nav {
  display: flex;
  gap: 28px;
  flex-wrap: wrap;
}

.main-nav a {
  color: var(--text);
  font-weight: 500;
  font-size: 0.95rem;
  transition: color 0.15s ease;
}

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

/* Hero */
.hero {
  padding: 96px 0 80px;
  text-align: center;
}

.hero h1 {
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 20px;
}

.hero .tagline {
  max-width: 640px;
  margin: 0 auto 36px;
  font-size: 1.15rem;
  color: var(--text-secondary);
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--text);
  color: #fff;
  padding: 12px 24px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  box-shadow: var(--shadow);
  transition: transform 0.15s ease, background 0.15s ease;
}

.badge:hover {
  background: var(--accent);
  transform: translateY(-2px);
}

/* Section headings */
.section-heading {
  text-align: center;
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 48px;
}

#features,
#support,
#privacy {
  padding: 80px 0;
}

#support {
  background: var(--card-bg);
}

/* Features grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 32px 28px;
}

.feature-card .icon {
  font-size: 2rem;
  margin-bottom: 16px;
}

.feature-card h3 {
  font-size: 1.15rem;
  margin: 0 0 10px;
}

.feature-card p {
  color: var(--text-secondary);
  margin: 0;
  font-size: 0.98rem;
}

/* Support */
.support-content {
  max-width: 720px;
  margin: 0 auto;
}

.contact-card {
  background: var(--bg);
  border-radius: var(--radius);
  padding: 24px 28px;
  text-align: center;
  margin-bottom: 40px;
  box-shadow: var(--shadow);
}

.contact-card a {
  font-weight: 600;
  font-size: 1.05rem;
}

.faq-item {
  background: var(--bg);
  border-radius: 14px;
  padding: 8px 24px;
  margin-bottom: 14px;
}

.faq-item summary {
  cursor: pointer;
  font-weight: 600;
  padding: 14px 0;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  float: right;
  color: var(--accent);
  font-weight: 700;
}

.faq-item[open] summary::after {
  content: "\2212";
}

.faq-item p {
  color: var(--text-secondary);
  margin: 0 0 18px;
}

/* Privacy */
.privacy-content {
  max-width: 720px;
  margin: 0 auto;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 40px 36px;
}

.effective-date {
  color: var(--text-secondary);
  font-weight: 600;
  margin-top: -8px;
}

.privacy-content h3 {
  font-size: 1.05rem;
  margin: 28px 0 8px;
}

.privacy-content p,
.privacy-content li {
  color: var(--text-secondary);
  font-size: 0.98rem;
}

/* Footer */
.site-footer {
  text-align: center;
  padding: 32px 24px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  border-top: 1px solid var(--border);
}

@media (max-width: 600px) {
  .hero {
    padding: 64px 0 56px;
  }

  #features,
  #support,
  #privacy {
    padding: 56px 0;
  }

  .privacy-content {
    padding: 28px 22px;
  }
}