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

:root {
  --bg: #0a0a0f;
  --surface: #14141f;
  --surface-hover: #1c1c2a;
  --accent: #6366f1;
  --accent-light: #818cf8;
  --accent-bg: rgba(99, 102, 241, 0.08);
  --ink: #f0eeea;
  --ink-mid: rgba(240, 238, 234, 0.45);
  --ink-light: rgba(240, 238, 234, 0.22);
  --border: rgba(240, 238, 234, 0.08);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --radius: 12px;
  --max-w: 760px;
}

html {
  scroll-behavior: smooth;
}

body {
  background: var(--bg);
  background-image: radial-gradient(ellipse 80% 60% at 50% -10%, rgba(99, 102, 241, 0.15) 0%, transparent 70%);
  color: var(--ink);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.7;
  min-height: 100vh;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.logo {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--ink);
  text-decoration: none;
  text-transform: uppercase;
}

.logo span {
  color: var(--accent-light);
}

.lang-switch {
  display: flex;
  gap: 8px;
}

.lang-switch a {
  padding: 6px 14px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 500;
  text-decoration: none;
  color: var(--ink-mid);
  border: 1px solid var(--border);
  transition: all 0.2s;
}

.lang-switch a:hover {
  color: var(--ink);
  border-color: var(--ink-light);
  background: var(--surface);
}

.lang-switch a.active {
  color: var(--accent-light);
  border-color: var(--accent);
  background: var(--accent-bg);
}

/* Footer */
footer {
  margin-top: 80px;
  padding: 40px 0;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--ink-mid);
  font-size: 14px;
}

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

footer a:hover {
  text-decoration: underline;
}

/* Hero */
.hero {
  padding: 80px 0 60px;
  text-align: center;
}

.hero h1 {
  font-size: 42px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
  line-height: 1.15;
}

.hero p {
  font-size: 18px;
  color: var(--ink-mid);
  max-width: 520px;
  margin: 0 auto;
}

.hero .badge {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 20px;
  background: var(--accent-bg);
  border: 1px solid rgba(99, 102, 241, 0.2);
  color: var(--accent-light);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 24px;
}

/* Nav pills */
.nav-pills {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin: 48px 0 64px;
  flex-wrap: wrap;
}

.nav-pills a {
  padding: 10px 20px;
  border-radius: 10px;
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  color: var(--ink-mid);
  border: 1px solid var(--border);
  transition: all 0.2s;
}

.nav-pills a:hover {
  color: var(--ink);
  background: var(--surface);
  border-color: var(--ink-light);
}

.nav-pills a.active {
  color: var(--accent-light);
  border-color: var(--accent);
  background: var(--accent-bg);
}

/* Section */
section {
  animation: fadeIn 0.5s ease both;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

.section-title {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-light);
  margin-bottom: 32px;
}

/* Article */
.article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  margin-bottom: 20px;
}

.article h2 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--ink);
}

.article h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--ink);
}

.article p {
  color: var(--ink-mid);
  font-size: 15px;
  line-height: 1.8;
}

.article ul {
  list-style: none;
  margin-top: 12px;
}

.article ul li {
  padding: 6px 0;
  padding-left: 20px;
  position: relative;
  color: var(--ink-mid);
  font-size: 15px;
}

.article ul li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--accent);
}

.highlight-box {
  background: var(--accent-bg);
  border: 1px solid rgba(99, 102, 241, 0.15);
  border-radius: 10px;
  padding: 20px;
  margin-top: 16px;
  font-size: 14px;
  color: var(--ink-mid);
}

.highlight-box strong {
  color: var(--accent-light);
}

/* FAQ */
.faq-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-item summary {
  padding: 20px 24px;
  cursor: pointer;
  font-weight: 500;
  font-size: 15px;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background 0.2s;
}

.faq-item summary:hover {
  background: var(--surface-hover);
}

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

.faq-item summary .arrow {
  color: var(--ink-light);
  transition: transform 0.25s;
  font-size: 18px;
}

.faq-item[open] summary .arrow {
  transform: rotate(180deg);
}

.faq-item .answer {
  padding: 0 24px 20px;
  color: var(--ink-mid);
  font-size: 15px;
  line-height: 1.8;
}

/* Feature cards */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
  margin: 32px 0;
}

.feature-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: border-color 0.2s, background 0.2s;
}

.feature-card:hover {
  border-color: rgba(99, 102, 241, 0.3);
  background: var(--surface-hover);
}

.feature-card h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 13px;
  color: var(--ink-mid);
  line-height: 1.6;
}

/* Contact */
.contact-section {
  text-align: center;
  padding: 48px 0;
}

.contact-section h2 {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 12px;
}

.contact-section p {
  color: var(--ink-mid);
  margin-bottom: 28px;
  font-size: 15px;
}

.contact-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  background: var(--accent);
  color: #fff;
  border-radius: 10px;
  text-decoration: none;
  font-weight: 600;
  font-size: 15px;
  transition: background 0.2s, transform 0.15s;
}

.contact-btn:hover {
  background: var(--accent-light);
  transform: translateY(-1px);
}

/* Divider */
.divider {
  height: 1px;
  background: var(--border);
  margin: 40px 0;
}

/* Responsive */
@media (max-width: 640px) {
  .hero { padding: 56px 0 40px; }
  .hero h1 { font-size: 30px; }
  .article { padding: 24px 20px; }
  .features-grid { grid-template-columns: 1fr 1fr; }
  .nav-pills { gap: 6px; }
  .nav-pills a { padding: 8px 14px; font-size: 13px; }
}