/* ============================================
   KDSS Website — Layout
   Navigation + Footer + Responsive
   ============================================ */

/* --- Navigation --- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 1000;
  transition: all var(--transition-slow);
  border-bottom: 1px solid transparent;
}

.navbar.scrolled {
  background: rgba(250, 251, 255, 0.9);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom-color: var(--border-color);
  box-shadow: 0 1px 8px rgba(37,99,235,0.06);
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 22px;
  font-weight: 800;
  letter-spacing: 1px;
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-logo img {
  width: 40px;
  height: 40px;
}

.nav-logo:hover {
  opacity: 0.85;
}

.nav-logo svg {
  width: 32px;
  height: 32px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.nav-link {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
  position: relative;
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-blue);
  border-radius: 1px;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

/* Language Switch / 语言切换 */
.lang-switch {
  display: flex;
  align-items: center;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  padding: 2px;
  border: 1px solid var(--border-color);
}

.lang-btn {
  padding: 4px 10px;
  font-size: 12px;
  font-weight: 600;
  border-radius: 4px;
  color: var(--text-muted);
  transition: all var(--transition-fast);
}

.lang-btn.active {
  background: var(--bg-secondary);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
}

.lang-btn:hover:not(.active) {
  color: var(--text-secondary);
}

/* GitHub link in nav */
.nav-github {
  display: flex;
  align-items: center;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

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

.nav-github svg {
  width: 22px;
  height: 22px;
}

/* Mobile Menu / 移动端菜单 */
.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}

.mobile-menu-btn span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: all var(--transition-base);
}

.mobile-menu-btn.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-btn.open span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-btn.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

.mobile-nav {
  display: none;
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--bg-primary);
  z-index: 999;
  padding: var(--space-xl);
  flex-direction: column;
  gap: var(--space-md);
}

.mobile-nav.open {
  display: flex;
}

.mobile-nav .nav-link {
  font-size: 18px;
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--border-color);
}

.mobile-nav .nav-actions {
  margin-top: var(--space-xl);
  justify-content: center;
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .nav-actions {
    display: none;
  }

  .mobile-nav .nav-actions {
    display: flex;
  }
}

/* --- Footer --- */
.footer {
  border-top: 1px solid var(--border-color);
  padding: var(--space-4xl) 0 var(--space-xl);
  background: linear-gradient(180deg, var(--bg-secondary) 0%, #e8edff 100%);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: var(--space-3xl);
  margin-bottom: var(--space-3xl);
}

.footer-brand p {
  font-size: 14px;
  margin-top: var(--space-md);
  max-width: 280px;
}

.footer-brand .nav-logo {
  margin-bottom: var(--space-sm);
}

.footer-col h4 {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-md);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-col a {
  display: block;
  font-size: 14px;
  color: var(--text-secondary);
  padding: 4px 0;
  transition: color var(--transition-fast);
}

.footer-col a:hover {
  color: var(--text-primary);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border-color);
}

.footer-bottom p {
  font-size: 13px;
  color: var(--text-muted);
}

.footer-bottom-links {
  display: flex;
  gap: var(--space-lg);
}

.footer-bottom-links a {
  font-size: 13px;
  color: var(--text-muted);
}

.footer-bottom-links a:hover {
  color: var(--text-secondary);
}

@media (max-width: 1024px) {
  .footer-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .footer-brand {
    grid-column: 1 / -1;
  }
}

@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-xl);
  }

  .footer-bottom {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }
}

/* --- Page Layout --- */
.page-header {
  padding: calc(var(--nav-height) + var(--space-4xl)) 0 var(--space-3xl);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.page-header::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 400px;
  background: radial-gradient(ellipse, rgba(37,99,235,0.08) 0%, rgba(124,58,237,0.03) 40%, transparent 70%);
  pointer-events: none;
}

.page-header h1 {
  margin-bottom: var(--space-md);
  position: relative;
}

.page-header p {
  font-size: 18px;
  max-width: 640px;
  margin: 0 auto;
  position: relative;
}

/* --- Docs Layout (sidebar + content) --- */
.docs-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: var(--space-3xl);
  padding-top: calc(var(--nav-height) + var(--space-xl));
  min-height: 100vh;
}

.docs-sidebar {
  position: sticky;
  top: calc(var(--nav-height) + var(--space-xl));
  height: fit-content;
  max-height: calc(100vh - var(--nav-height) - var(--space-xl));
  overflow-y: auto;
  padding-right: var(--space-md);
  border-right: 1px solid var(--border-color);
}

.docs-sidebar-group {
  margin-bottom: var(--space-lg);
}

.docs-sidebar-group h4 {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: var(--space-sm);
  padding: 0 var(--space-md);
}

.docs-sidebar a {
  display: block;
  padding: 6px var(--space-md);
  font-size: 14px;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.docs-sidebar a:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

.docs-sidebar a.active {
  color: var(--accent-blue);
  background: rgba(37,99,235,0.08);
}

.docs-content {
  max-width: 800px;
  padding-bottom: var(--space-4xl);
}

.docs-content h2 {
  margin-top: var(--space-3xl);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--border-color);
}

.docs-content h3 {
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
}

.docs-content p {
  margin-bottom: var(--space-md);
}

.docs-content ul, .docs-content ol {
  margin-bottom: var(--space-md);
  padding-left: var(--space-lg);
}

.docs-content li {
  color: var(--text-secondary);
  font-size: 15px;
  margin-bottom: var(--space-sm);
  list-style: disc;
}

.docs-content ol li {
  list-style: decimal;
}

@media (max-width: 1024px) {
  .docs-layout {
    grid-template-columns: 1fr;
  }

  .docs-sidebar {
    position: static;
    max-height: none;
    border-right: none;
    border-bottom: 1px solid var(--border-color);
    padding-right: 0;
    padding-bottom: var(--space-lg);
    margin-bottom: var(--space-lg);
  }
}