:root {
  --bg-color: #0d1117;
  --bg-surface: #161b22;
  --bg-surface-elevated: #21262d;
  --text-primary: #c9d1d9;
  --text-secondary: #8b949e;
  --text-heading: #f0f6fc;
  --accent-color: #58a6ff;
  --accent-glow: rgba(88, 166, 255, 0.4);
  --border-color: #30363d;
  --success-color: #238636;
  --warning-color: #d29922;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 24px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1200px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

a:hover {
  filter: brightness(1.2);
}

button {
  cursor: pointer;
  font-family: inherit;
  border: none;
  background: none;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

@keyframes pulse-glow {
  0% { box-shadow: 0 0 0 0 var(--accent-glow); }
  70% { box-shadow: 0 0 0 10px rgba(88, 166, 255, 0); }
  100% { box-shadow: 0 0 0 0 rgba(88, 166, 255, 0); }
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-10px); }
  100% { transform: translateY(0px); }
}

/* Layout Helpers */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

.text-center { text-align: center; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.mb-4 { margin-bottom: 32px; }
.mb-5 { margin-bottom: 48px; }

/* Navigation */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 72px;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 20px;
  font-weight: 700;
  color: var(--text-heading);
}

.nav-logo svg {
  width: 32px;
  height: 32px;
  color: var(--accent-color);
}

.nav-links {
  display: flex;
  gap: 8px;
}

.nav-link {
  color: var(--text-secondary);
  font-weight: 500;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.nav-link:hover {
  color: var(--text-heading);
  background-color: var(--bg-surface-elevated);
}

.nav-link.active {
  color: var(--accent-color);
  background-color: rgba(88, 166, 255, 0.1);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  font-size: 16px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.btn-primary {
  background-color: var(--accent-color);
  color: #0d1117;
}

.btn-primary:hover {
  background-color: #79c0ff;
  box-shadow: 0 0 16px var(--accent-glow);
}

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

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

.btn-lg {
  padding: 16px 32px;
  font-size: 18px;
}

/* Hero Section */
.hero {
  padding: 100px 0 80px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -20%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 600px;
  background: radial-gradient(circle, rgba(88,166,255,0.15) 0%, rgba(13,17,23,0) 70%);
  z-index: -1;
  pointer-events: none;
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background-color: rgba(88, 166, 255, 0.1);
  color: var(--accent-color);
  border: 1px solid rgba(88, 166, 255, 0.2);
  border-radius: 100px;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 24px;
}

.hero-title {
  font-size: 56px;
  font-weight: 800;
  line-height: 1.1;
  color: var(--text-heading);
  margin-bottom: 24px;
  letter-spacing: -0.02em;
}

.hero-title span {
  background: linear-gradient(120deg, var(--accent-color), #bc8cff);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  font-size: 20px;
  color: var(--text-secondary);
  margin-bottom: 40px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

/* Feature Grid - Cyber Cards */
.section {
  padding: 80px 0;
}

.section-header {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 60px;
}

.section-title {
  font-size: 36px;
  font-weight: 700;
  color: var(--text-heading);
  margin-bottom: 16px;
}

.cyber-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.cyber-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 32px;
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}

.cyber-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 0;
  background-color: var(--accent-color);
  transition: var(--transition);
}

.cyber-card:hover {
  transform: translateY(-5px);
  border-color: var(--accent-color);
  box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}

.cyber-card:hover::before {
  height: 100%;
}

.cyber-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: rgba(88, 166, 255, 0.1);
  color: var(--accent-color);
  border-radius: var(--radius-sm);
  margin-bottom: 24px;
}

.cyber-icon svg {
  width: 24px;
  height: 24px;
}

.cyber-card h3 {
  font-size: 20px;
  color: var(--text-heading);
  margin-bottom: 12px;
}

.cyber-card p {
  color: var(--text-secondary);
  font-size: 15px;
}

/* Alternating Rows */
.alt-row {
  display: flex;
  align-items: center;
  gap: 60px;
  margin-bottom: 80px;
}

.alt-row:nth-child(even) {
  flex-direction: row-reverse;
}

.alt-content {
  flex: 1;
}

.alt-visual {
  flex: 1;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.alt-visual svg {
  width: 200px;
  height: 200px;
  color: var(--text-secondary);
  animation: float 6s ease-in-out infinite;
}

/* Reviews */
.reviews {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}

.review-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
}

.review-stars {
  color: var(--warning-color);
  display: flex;
  gap: 4px;
  margin-bottom: 16px;
}

.review-stars svg { width: 16px; height: 16px; }

.review-text {
  font-style: italic;
  margin-bottom: 24px;
  color: var(--text-heading);
}

.review-author {
  display: flex;
  align-items: center;
  gap: 12px;
}

.review-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background-color: var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  color: var(--text-primary);
}

/* FAQ Accordion */
.faq-container {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-q {
  padding: 20px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  font-weight: 600;
  color: var(--text-heading);
  user-select: none;
}

.faq-icon {
  color: var(--text-secondary);
  transition: transform 0.3s ease;
}

.faq-icon svg { width: 20px; height: 20px; }

.faq-a {
  padding: 0 24px;
  max-height: 0;
  opacity: 0;
  transition: all 0.3s ease;
  color: var(--text-secondary);
  border-top: 1px solid transparent;
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
  color: var(--accent-color);
}

.faq-item.active .faq-a {
  padding: 20px 24px;
  max-height: 400px;
  opacity: 1;
  border-top-color: var(--border-color);
}

/* Download Cards */
.dl-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 24px;
}

.dl-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.dl-card.featured {
  background-color: var(--bg-surface-elevated);
  border-color: var(--accent-color);
  box-shadow: 0 0 20px rgba(88, 166, 255, 0.1);
  transform: scale(1.02);
}

.dl-icon {
  width: 64px;
  height: 64px;
  color: var(--text-heading);
  margin-bottom: 16px;
}

.dl-icon svg { width: 100%; height: 100%; }

.dl-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--text-heading);
  margin-bottom: 8px;
}

.dl-desc {
  color: var(--text-secondary);
  font-size: 14px;
  margin-bottom: 24px;
  flex-grow: 1;
}

.dl-meta {
  font-size: 13px;
  color: var(--text-secondary);
  margin-top: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

/* Article Layout (zh-cn) */
.article-layout {
  display: flex;
  gap: 40px;
  align-items: flex-start;
}

.article-main {
  flex: 1;
}

.article-sidebar {
  width: 320px;
  position: sticky;
  top: 100px;
}

.article-content {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 40px;
}

.article-content h2 {
  color: var(--text-heading);
  font-size: 28px;
  margin: 40px 0 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.article-content h2:first-child { margin-top: 0; }

.article-content h3 {
  color: var(--text-heading);
  font-size: 20px;
  margin: 24px 0 16px;
}

.article-content p {
  margin-bottom: 16px;
  color: var(--text-primary);
}

.article-content ul {
  margin-bottom: 24px;
  padding-left: 24px;
}

.article-content li {
  margin-bottom: 8px;
}

/* Tags */
.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 32px;
}

.tag {
  padding: 4px 12px;
  background-color: var(--bg-surface-elevated);
  border: 1px solid var(--border-color);
  border-radius: 100px;
  font-size: 13px;
  color: var(--text-secondary);
}

/* Sidebar Widget */
.widget {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-bottom: 24px;
}

.widget-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-heading);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.widget-list {
  list-style: none;
  padding: 0;
}

.widget-list li {
  margin-bottom: 12px;
}

.widget-list a {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-secondary);
}

.widget-list a:hover {
  color: var(--accent-color);
}

/* Footer */
.footer {
  border-top: 1px solid var(--border-color);
  padding: 40px 0;
  background-color: var(--bg-surface);
  margin-top: 80px;
  text-align: center;
}

.security-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background-color: rgba(35, 134, 54, 0.1);
  color: var(--success-color);
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(35, 134, 54, 0.2);
  margin-bottom: 24px;
  font-weight: 500;
  font-size: 14px;
}

.security-badge svg { width: 18px; height: 18px; }

.footer-text {
  color: var(--text-secondary);
  font-size: 14px;
}

/* Responsive */
@media (max-width: 768px) {
  .hero-title { font-size: 40px; }
  .alt-row, .alt-row:nth-child(even) { flex-direction: column; gap: 40px; }
  .article-layout { flex-direction: column; }
  .article-sidebar { width: 100%; position: static; }
  .nav-links { display: none; }
}