:root {
  --bg: #f4f6fb;
  --surface: #ffffff;
  --surface-2: #eef2f9;
  --ink: #0f1b2d;
  --ink-soft: #4b5a6e;
  --ink-faint: #8a97ab;
  --brand: #00529f;
  --brand-2: #0077cc;
  --accent-1: #4f46e5;
  --accent-2: #06b6d4;
  --link: #0077cc;
  --link-hover: #00529f;
  --sidebar-w: 300px;
  --radius: 18px;
  --radius-sm: 12px;
  --shadow-sm: 0 2px 8px rgba(15, 27, 45, 0.06);
  --shadow-md: 0 10px 30px rgba(15, 27, 45, 0.1);
  --shadow-lg: 0 24px 60px rgba(15, 27, 45, 0.16);
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;

  /* Sidebar / nav palette */
  --nav-bg: linear-gradient(180deg, #0a1220 0%, #0e1a33 55%, #123047 100%);
  --nav-ink: #cbd5e1;
  --nav-link-ink: #dbe4f0;
  --nav-link-hover-bg: rgba(255, 255, 255, 0.08);
  --nav-link-hover-ink: #ffffff;
  --nav-active-bg: linear-gradient(90deg, rgba(59, 130, 246, 0.35), rgba(124, 58, 237, 0.3));
  --nav-active-ink: #ffffff;
  --nav-active-inset: rgba(147, 197, 253, 0.35);
  --nav-chev-ink: #7d8fa8;
  --nav-tree-line: linear-gradient(180deg, rgba(56, 189, 248, 0.55) 0%, rgba(125, 143, 168, 0.15) 100%);
  --nav-sub-ink: #9fb0c8;
  --nav-sub-hover-bg: rgba(56, 189, 248, 0.09);
  --nav-sub-active-bg: rgba(56, 189, 248, 0.1);
  --nav-sub-hover-ink: #ffffff;
  --nav-sub-active-ink: #ffffff;
  --nav-dot-border: #3f5575;
  --nav-dot-bg: #0e1a33;
  --nav-accent: #38bdf8;
  --nav-glow: rgba(56, 189, 248, 0.2);
  --nav-badge-bg: rgba(56, 189, 248, 0.18);
  --nav-soft-accent: #7dd3fc;
  --nav-border: rgba(255, 255, 255, 0.08);
  --nav-foot-ink: #8296b2;
  --nav-foot-link: #93c5fd;

  /* Footer palette */
  --foot-bg: linear-gradient(180deg, #0e1a33, #0a1220);
  --foot-ink: #94a3b8;
  --foot-heading-ink: #e2e8f0;
  --foot-link: #93c5fd;
  --foot-link-hover: #dbeafe;
  --foot-accent: #38bdf8;
  --foot-border: rgba(255, 255, 255, 0.08);
  --foot-bottom-ink: #64748b;

  /* Surfaces / misc */
  --card-border: rgba(15, 27, 45, 0.05);
  --feature-border: rgba(15, 27, 45, 0.06);
  --img-frame-border: rgba(15, 27, 45, 0.08);
  --img-frame-bg: #ffffff;
  --scrollbar-thumb: rgba(15, 27, 45, 0.18);
  --nav-scrollbar-thumb: rgba(255, 255, 255, 0.18);
  --backdrop: rgba(10, 18, 32, 0.55);
  --mobile-header-bg: #ffffff;
  --mobile-header-border: rgba(15, 27, 45, 0.08);
  --chat-frame-bg: #f0f4f8;
  --hero-ink: #ffffff;
  --hero-soft: #c9d6ea;
  --hero-accent: #7dd3fc;
}

/* Светлая тема */
[data-theme="light"] {
  --bg: #f8fafd;
  --surface: #ffffff;
  --surface-2: #eef2f8;
  --ink: #16233a;
  --ink-soft: #4d5f7a;
  --ink-faint: #7d8ca1;
  --brand: #00529f;
  --brand-2: #0077cc;
  --link: #0066b3;
  --link-hover: #004d8a;

  --nav-bg: linear-gradient(180deg, #ffffff 0%, #f2f5fb 55%, #e8eef7 100%);
  --nav-ink: #34405a;
  --nav-link-ink: #1f2c44;
  --nav-link-hover-bg: rgba(0, 119, 204, 0.06);
  --nav-link-hover-ink: #0f1b2d;
  --nav-active-bg: linear-gradient(90deg, rgba(0, 119, 204, 0.16), rgba(79, 70, 229, 0.14));
  --nav-active-ink: #0f1b2d;
  --nav-active-inset: rgba(0, 119, 204, 0.25);
  --nav-chev-ink: #93a3b8;
  --nav-tree-line: linear-gradient(180deg, rgba(0, 119, 204, 0.5) 0%, rgba(125, 143, 168, 0.15) 100%);
  --nav-sub-ink: #4d5f7a;
  --nav-sub-hover-bg: rgba(0, 119, 204, 0.07);
  --nav-sub-active-bg: rgba(0, 119, 204, 0.1);
  --nav-sub-hover-ink: #16233a;
  --nav-sub-active-ink: #16233a;
  --nav-dot-border: #c4d0e0;
  --nav-dot-bg: #ffffff;
  --nav-accent: #0077cc;
  --nav-glow: rgba(0, 119, 204, 0.18);
  --nav-badge-bg: rgba(0, 119, 204, 0.12);
  --nav-soft-accent: #0066b3;
  --nav-border: rgba(15, 27, 45, 0.08);
  --nav-foot-ink: #5b6b82;
  --nav-foot-link: #0066b3;

  --foot-bg: linear-gradient(180deg, #ffffff, #eef2f8);
  --foot-ink: #5b6b82;
  --foot-heading-ink: #243048;
  --foot-link: #0066b3;
  --foot-link-hover: #004d8a;
  --foot-accent: #0077cc;
  --foot-border: rgba(15, 27, 45, 0.08);
  --foot-bottom-ink: #8a97ab;

  --card-border: rgba(15, 27, 45, 0.06);
  --feature-border: rgba(15, 27, 45, 0.06);
  --img-frame-border: rgba(15, 27, 45, 0.08);
  --img-frame-bg: #ffffff;
  --scrollbar-thumb: rgba(15, 27, 45, 0.16);
  --nav-scrollbar-thumb: rgba(15, 27, 45, 0.2);
  --backdrop: rgba(15, 27, 45, 0.4);
  --mobile-header-bg: #ffffff;
  --mobile-header-border: rgba(15, 27, 45, 0.08);
}

/* Тёмная тема */
[data-theme="dark"] {
  --bg: #0b1220;
  --surface: #151e30;
  --surface-2: #1c2740;
  --ink: #e7edf6;
  --ink-soft: #b6c2d4;
  --ink-faint: #8494ac;
  --brand: #8ab4f8;
  --brand-2: #6aa5ff;
  --link: #7fb2ff;
  --link-hover: #a8c9ff;

  --foot-bg: linear-gradient(180deg, #101a30, #0a1220);
  --foot-bottom-ink: #7d8ba0;

  --card-border: rgba(255, 255, 255, 0.08);
  --feature-border: rgba(255, 255, 255, 0.08);
  --img-frame-border: rgba(255, 255, 255, 0.12);
  --img-frame-bg: #0e1626;
  --scrollbar-thumb: rgba(255, 255, 255, 0.2);
  --nav-scrollbar-thumb: rgba(255, 255, 255, 0.24);
  --backdrop: rgba(0, 0, 0, 0.6);
  --mobile-header-bg: #151e30;
  --mobile-header-border: rgba(255, 255, 255, 0.08);
  --chat-frame-bg: #151e30;
}

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

html { scroll-behavior: smooth; scroll-padding-top: 24px; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { max-width: 100%; height: auto; display: block; }

a { color: var(--link); text-decoration: none; }
a:hover { color: var(--link-hover); text-decoration: underline; }

h1, h2, h3, h4 { line-height: 1.25; font-weight: 800; letter-spacing: -0.01em; }
h1 { font-size: clamp(1.9rem, 3.4vw, 2.8rem); }
h2 { font-size: clamp(1.5rem, 2.4vw, 2rem); }
h3 { font-size: 1.25rem; }

/* ---------------------------------------------------------------- */
/* Layout                                                           */
/* ---------------------------------------------------------------- */

.layout { display: flex; min-height: 100vh; }

/* Sidebar */
.sidebar {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: var(--sidebar-w);
  display: flex;
  flex-direction: column;
  background: var(--nav-bg);
  color: var(--nav-ink);
  z-index: 60;
  overflow-y: auto;
  scrollbar-gutter: stable;
  box-shadow: 4px 0 24px rgba(10, 18, 32, 0.25);
}

.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 20px 18px 16px;
  border-bottom: 1px solid var(--nav-border);
}

.sidebar-brand .logo-img {
  width: 100%;
  height: auto;
  border-radius: var(--radius);
  filter: drop-shadow(0 2px 8px rgba(0, 0, 0, 0.4));
}

.sidebar-tagline {
  font-size: 0.72rem;
  color: var(--nav-soft-accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 600;
}

/* Menu */
.sidebar-nav { flex: 1; padding: 14px 12px 24px; }

.nav-section { margin-bottom: 4px; }

.nav-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 8px 14px;
  border-radius: 12px;
  color: var(--nav-link-ink);
  font-weight: 600;
  font-size: 0.95rem;
  transition: background 0.2s, color 0.2s;
  cursor: pointer;
  user-select: none;
}
a.nav-link:hover { text-decoration: none; background: var(--nav-link-hover-bg); color: var(--nav-link-hover-ink); }
.nav-link.active { background: var(--nav-active-bg); color: var(--nav-active-ink); box-shadow: inset 0 0 0 1px var(--nav-active-inset); }

.nav-link .chev { font-size: 0.7rem; color: var(--nav-chev-ink); transition: transform 0.25s; }
.nav-section.open .nav-link .chev { transform: rotate(90deg); }

.nav-sub { display: grid; grid-template-rows: 0fr; transition: grid-template-rows 0.3s ease; }
.nav-section.open .nav-sub { grid-template-rows: 1fr; }
.nav-sub-inner { overflow: hidden; position: relative; }

/* Вертикальная соединительная линия дерева */
.nav-sub-inner::before {
  content: "";
  position: absolute;
  top: 10px;
  bottom: 10px;
  left: 23px;
  width: 2px;
  border-radius: 2px;
  background: var(--nav-tree-line);
}

.nav-sub-link {
  position: relative;
  display: block;
  padding: 8px 12px 8px 42px;
  margin: 2px 0;
  border-radius: 10px;
  font-size: 0.87rem;
  color: var(--nav-sub-ink);
  transition: background 0.2s, color 0.2s;
}

/* Точка-маркер на соединительной линии */
.nav-sub-link::before {
  content: "";
  position: absolute;
  left: 20px;
  top: 50%;
  transform: translateY(-50%);
  width: 8px;
  height: 8px;
  border-radius: 50%;
  border: 2px solid var(--nav-dot-border);
  background: var(--nav-dot-bg);
  box-sizing: border-box;
  transition: background 0.2s, border-color 0.2s, box-shadow 0.2s;
}

.nav-sub-link:hover { text-decoration: none; background: var(--nav-sub-hover-bg); color: var(--nav-sub-hover-ink); }
.nav-sub-link:hover::before { background: var(--nav-accent); border-color: var(--nav-accent); box-shadow: 0 0 0 4px var(--nav-glow); }
.nav-sub-link.active { color: var(--nav-sub-active-ink); background: var(--nav-sub-active-bg); }
.nav-sub-link.active::before { background: var(--nav-accent); border-color: var(--nav-accent); box-shadow: 0 0 0 4px var(--nav-glow); }

.nav-badge {
  margin-left: auto;
  font-size: 0.6rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--nav-badge-bg);
  color: var(--nav-soft-accent);
  white-space: nowrap;
}

/* Sidebar footer */
.sidebar-foot {
  padding: 16px 18px;
  border-top: 1px solid var(--nav-border);
  font-size: 0.78rem;
  color: var(--nav-foot-ink);
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.sidebar-foot a { color: var(--nav-foot-link); }

/* Theme switcher */
.theme-switch {
  display: flex;
  gap: 4px;
  padding: 3px;
  margin-bottom: 4px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--nav-border);
}
.theme-btn {
  flex: 1;
  border: none;
  cursor: pointer;
  padding: 6px 8px;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 700;
  font-family: inherit;
  color: var(--nav-sub-ink);
  background: transparent;
  transition: background 0.2s, color 0.2s;
  white-space: nowrap;
}
.theme-btn:hover { color: var(--nav-link-hover-ink); }
.theme-btn[aria-pressed="true"] {
  background: var(--nav-active-bg);
  color: var(--nav-active-ink);
  box-shadow: inset 0 0 0 1px var(--nav-active-inset);
}

/* Main */
.main {
  flex: 1;
  margin-left: var(--sidebar-w);
  min-width: 0;
  display: flex;
  flex-direction: column;
}

.content {
  flex: 1;
  max-width: 960px;
  width: 100%;
  margin: 0 auto;
  padding: 48px 40px 80px;
}

/* ---------------------------------------------------------------- */
/* Components                                                       */
/* ---------------------------------------------------------------- */

.breadcrumb {
  font-size: 0.82rem;
  color: var(--ink-faint);
  margin-bottom: 18px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
}
.breadcrumb a { color: var(--link); }
.breadcrumb .sep { opacity: 0.5; }

.lead {
  font-size: 1.18rem;
  color: var(--ink-soft);
  font-weight: 500;
  margin: 14px 0 24px;
  line-height: 1.6;
}

.card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: 32px;
  margin: 22px 0;
  border: 1px solid var(--card-border);
}

.card h2 { margin-bottom: 14px; }
.card h3 { margin-bottom: 10px; }
.card p { margin-bottom: 14px; color: var(--ink-soft); }
.card p:last-child { margin-bottom: 0; }
.card ul, .card ol { margin: 0 0 14px 20px; color: var(--ink-soft); }
.card li { margin-bottom: 8px; }

.content section > h2 { margin: 22px 0 4px; }

.hero {
  position: relative;
  border-radius: 24px;
  overflow: hidden;
  color: var(--hero-ink);
  padding: 24px 40px;
  margin-bottom: 28px;
  background:
    radial-gradient(1100px 500px at 85% -20%, rgba(124, 58, 237, 0.55), transparent 60%),
    radial-gradient(900px 480px at 10% 120%, rgba(6, 182, 212, 0.4), transparent 55%),
    linear-gradient(135deg, #0b1530 0%, #123a66 60%, #0a2442 100%);
  box-shadow: var(--shadow-lg);
}
.hero::after {
  content: "";
  position: absolute; inset: 0;
  background-image: radial-gradient(rgba(255, 255, 255, 0.14) 1px, transparent 1px);
  background-size: 22px 22px;
  pointer-events: none;
  opacity: 0.35;
}
.hero > * { position: relative; z-index: 1; }
.hero .kicker {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--hero-accent);
  margin-bottom: 14px;
}
.hero h1 { margin-bottom: 10px; font-size: clamp(1.4rem, 2.8vw, 2.1rem); }
.hero h2 { margin-bottom: 10px; font-size: clamp(1.4rem, 2.8vw, 2.1rem); }
.hero p.lead { color: var(--hero-soft); margin-bottom: 8px; max-width: 640px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 26px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.95rem;
  border: none;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.2s, background 0.2s;
  text-decoration: none;
}
.btn:hover { transform: translateY(-2px); text-decoration: none; }
.btn-primary { background: linear-gradient(135deg, var(--brand-2), var(--accent-1)); color: #fff; box-shadow: 0 10px 24px rgba(79, 70, 229, 0.35); }
.btn-primary:hover { box-shadow: 0 14px 30px rgba(79, 70, 229, 0.45); }
.btn-ghost { background: rgba(255, 255, 255, 0.1); color: #fff; border: 1px solid rgba(255, 255, 255, 0.35); backdrop-filter: blur(4px); }
.btn-ghost:hover { background: rgba(255, 255, 255, 0.18); }

.img-frame {
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--img-frame-border);
  box-shadow: var(--shadow-md);
  background: var(--img-frame-bg);
  margin: 18px 0;
}
.img-frame img { width: 100%; }
.img-caption {
  font-size: 0.82rem;
  color: var(--ink-faint);
  text-align: center;
  margin: 14px 18px 18px;
}

.callout {
  border-left: 4px solid var(--accent-2);
  background: linear-gradient(135deg, rgba(6, 182, 212, 0.08), rgba(79, 70, 229, 0.08));
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 18px 22px;
  margin: 20px 0;
  color: var(--ink-soft);
}
.callout strong { color: var(--ink); }

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  margin: 22px 0;
}
.feature {
  background: var(--surface);
  border-radius: var(--radius-sm);
  padding: 24px 20px;
  border: 1px solid var(--feature-border);
  box-shadow: var(--shadow-sm);
}
.feature .ico {
  width: 44px; height: 44px;
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem;
  margin-bottom: 12px;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.15), rgba(124, 58, 237, 0.15));
}
.feature h3 { font-size: 1.02rem; margin-bottom: 6px; }
.feature p { font-size: 0.9rem; color: var(--ink-soft); }

.anchor-tag {
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--brand-2);
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.2);
  padding: 3px 10px;
  border-radius: 999px;
  vertical-align: 4px;
  margin-left: 8px;
  white-space: nowrap;
}

/* Floating chat widget (bottom-right) */
.chat-fab-wrap {
  position: fixed;
  bottom: 22px; right: 22px;
  z-index: 60;
  display: flex; flex-direction: column; align-items: flex-end;
  gap: 12px;
}
.chat-frame {
  width: 380px; max-width: calc(100vw - 32px);
  height: 560px;
  border: 0;
  border-radius: 20px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  display: none;
  background: var(--chat-frame-bg);
}
.chat-frame.open { display: block; animation: popIn 0.25s ease; }
@keyframes popIn {
  from { opacity: 0; transform: translateY(16px) scale(0.97); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}
.chat-fab {
  width: 60px; height: 60px;
  border-radius: 50%;
  border: none;
  cursor: pointer;
  color: #fff;
  font-size: 26px;
  background: linear-gradient(135deg, var(--brand-2), var(--accent-1));
  box-shadow: 0 12px 28px rgba(79, 70, 229, 0.45);
  display: flex; align-items: center; justify-content: center;
  transition: transform 0.2s;
}
.chat-fab:hover { transform: scale(1.08); }
.chat-fab .fab-close { display: none; }
.chat-fab.open .fab-open { display: none; }
.chat-fab.open .fab-close { display: inline; }

/* ---------------------------------------------------------------- */
/* Footer                                                           */
/* ---------------------------------------------------------------- */

.footer {
  background: var(--foot-bg);
  color: var(--foot-ink);
  padding: 48px 40px 40px;
  margin-left: 0;
}
.footer-inner {
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 40px;
  justify-content: space-between;
}
.footer h4 {
  color: var(--foot-heading-ink);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 16px;
}
.footer .cols { display: flex; flex-wrap: wrap; gap: 48px; }
.footer ul { list-style: none; }
.footer li { margin-bottom: 10px; font-size: 0.93rem; }
.footer a { color: var(--foot-link); }
.footer a:hover { color: var(--foot-link-hover); }
.footer .contact-line { display: flex; align-items: center; gap: 10px; }
.footer .contact-line .ico { color: var(--foot-accent); width: 20px; text-align: center; }
.footer-bottom {
  max-width: 960px;
  margin: 32px auto 0;
  padding-top: 24px;
  border-top: 1px solid var(--foot-border);
  font-size: 0.82rem;
  color: var(--foot-bottom-ink);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: space-between;
}

/* ---------------------------------------------------------------- */
/* Mobile / responsive                                              */
/* ---------------------------------------------------------------- */

.hamburger {
  display: none;
  position: fixed;
  top: 14px; left: 14px;
  z-index: 70;
  width: 46px; height: 46px;
  border-radius: 12px;
  border: none;
  background: linear-gradient(135deg, var(--brand-2), var(--accent-1));
  color: #fff;
  font-size: 20px;
  cursor: pointer;
  box-shadow: var(--shadow-md);
}

.sidebar-backdrop {
  display: none;
  position: fixed; inset: 0;
  background: var(--backdrop);
  z-index: 55;
}

/* Mobile top header (visible on small screens) */
.mobile-header {
  display: none;
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 58px;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 0 12px 0 10px;
  background: var(--mobile-header-bg);
  border-bottom: 1px solid var(--mobile-header-border);
  box-shadow: 0 6px 18px rgba(15, 27, 45, 0.06);
  z-index: 65;
}

@media (max-width: 1024px) {
  .mobile-header { display: flex; }
  .hamburger { display: flex; align-items: center; justify-content: center; position: static; top: auto; left: auto; z-index: auto; }
  .sidebar {
    transform: translateX(-100%);
    transition: transform 0.3s ease;
  }
  .sidebar.open { transform: translateX(0); }
  aside.sidebar.open ~ .mobile-header { display: none; }
  .sidebar-backdrop.show { display: block; }
  .main { margin-left: 0; }
  .content { padding: 76px 20px 60px; }
  .hero { padding: 18px 26px; }
  .card { padding: 24px; }
  .footer { padding: 40px 24px; }
  .chat-frame { height: 480px; }
}

/* Scrollbar */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); border-radius: 999px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--nav-scrollbar-thumb); }

/* Reveal animation */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .nav-sub { transition: none; }
}