:root {
  --ink: #111;
  --muted: #666;
  --paper: #fafafa;
  --line: #ececec;
  --brand: #1a73e8;
  --brand-dark: #0a3d8f;
  --link: #0a58ff;
  --bg-soft: #f5f7fb;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  font-size: 17px;
  line-height: 1.55;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.container {
  max-width: 880px;
  margin: 0 auto;
  padding: 0 24px;
}

a { color: var(--link); }

/* ---------- LANG SWITCH ---------- */

.lang-switch {
  position: absolute;
  top: 16px;
  right: 20px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: rgba(255,255,255,.85);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 4px;
  font-size: 12px;
  font-weight: 600;
  z-index: 10;
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}

.lang-switch a,
.lang-switch span {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 999px;
  text-decoration: none;
  color: var(--muted);
  letter-spacing: 0.04em;
}

.lang-switch a:hover { background: #f3f3f3; color: var(--ink); }

.lang-switch span[aria-current="page"] {
  background: var(--ink);
  color: #fff;
}

/* ---------- HERO ---------- */

.hero {
  background: linear-gradient(160deg, #fff 0%, var(--bg-soft) 100%);
  border-bottom: 1px solid var(--line);
  padding: 48px 0 64px;
  text-align: center;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 18px;
  margin-bottom: 32px;
}

.brand img {
  border-radius: 8px;
}

h1 {
  font-size: clamp(36px, 5vw, 56px);
  line-height: 1.05;
  letter-spacing: -0.025em;
  font-weight: 800;
  margin: 0 0 20px;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}

.lede {
  font-size: clamp(17px, 2vw, 20px);
  color: #333;
  max-width: 640px;
  margin: 0 auto 32px;
}

.lede strong { color: var(--ink); font-weight: 600; }

.cta {
  display: inline-block;
  background: var(--ink);
  color: #fff;
  text-decoration: none;
  padding: 14px 28px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 17px;
  transition: filter 120ms ease, transform 80ms ease;
  box-shadow: 0 6px 24px rgba(0,0,0,.12);
}

.cta:hover { filter: brightness(1.15); transform: translateY(-1px); }
.cta:active { transform: translateY(0); }

.meta {
  margin-top: 14px;
  color: var(--muted);
  font-size: 14px;
}

/* ---------- SECTIONS ---------- */

main section {
  padding: 56px 0;
  border-top: 1px solid var(--line);
}

main section:first-of-type { border-top: 0; }

h2 {
  font-size: clamp(24px, 3vw, 30px);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 24px;
}

h3 {
  font-size: 18px;
  font-weight: 600;
  margin: 0 0 8px;
}

p { margin: 0 0 12px; }

.steps {
  margin: 0;
  padding-left: 24px;
}

.steps li {
  margin-bottom: 10px;
}

/* ---------- FEATURE GRID ---------- */

.grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.grid article {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 20px;
}

/* ---------- PLATFORMS ---------- */

.platforms {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.platforms li {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 8px 16px;
  font-size: 15px;
  font-weight: 500;
}

/* ---------- FAQ ---------- */

#faq details {
  border-top: 1px solid var(--line);
  padding: 18px 0;
}

#faq details:first-of-type { border-top: 0; padding-top: 0; }
#faq details:last-of-type { border-bottom: 1px solid var(--line); }

#faq summary {
  cursor: pointer;
  font-weight: 600;
  font-size: 17px;
  list-style: none;
  position: relative;
  padding-right: 28px;
}

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

#faq summary::after {
  content: "+";
  position: absolute;
  right: 4px;
  top: -2px;
  font-size: 22px;
  color: var(--muted);
  font-weight: 400;
  transition: transform 200ms ease;
}

#faq details[open] summary::after { content: "−"; }

#faq details p {
  margin-top: 12px;
  color: #333;
}

/* ---------- INLINE CODE & KBD ---------- */

code {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.92em;
  background: #f3f3f3;
  padding: 2px 6px;
  border-radius: 4px;
}

kbd {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.85em;
  background: #fff;
  border: 1px solid #ddd;
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 1px 7px;
  white-space: nowrap;
}

/* ---------- FOOTER ---------- */

footer {
  border-top: 1px solid var(--line);
  padding: 28px 0;
  background: #fff;
  text-align: center;
  color: var(--muted);
  font-size: 14px;
}

footer p { margin: 4px 0; }

/* ---------- RESPONSIVE ---------- */

@media (max-width: 540px) {
  .hero { padding: 32px 0 48px; }
  main section { padding: 40px 0; }
  .cta { width: 100%; }
}