:root {
  --bg: #0A192F;
  --bg-glass: rgba(17, 34, 64, 0.72);
  --bg-2: #112240;
  --bg-ink: #1A1A2E;
  --text: #F5F0E6;
  --text-strong: #FFFFFF;
  --text-dim: #A8B2D1;
  --accent-1: #00FFA3;
  --accent-2: #7B2FFF;
  --accent-3: #FFD700;
  --danger: #FF5C5C;
  --radius: 12px;
  --max-w: 1200px;
  --header-h: 6rem;
  --font-sans: 'Rajdhani', 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
  --font-display: 'Road Rage', 'Impact', 'Arial Black', sans-serif;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 400;
  line-height: 1.75;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--text-strong);
  font-weight: bold;
  line-height: 1.05;
  letter-spacing: 0.01em;
  margin: 0 0 0.75em;
}

p {
  margin: 0 0 1em;
}

a {
  color: var(--accent-1);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover,
a:focus-visible {
  color: var(--accent-2);
}

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

ul,
ol {
  padding: 0;
  margin: 0;
}

#main-content {
  display: block;
  flex: 1 0 auto;
}

#main-content:focus {
  outline: none;
}

:focus-visible {
  outline: 2px solid var(--accent-1);
  outline-offset: 3px;
  border-radius: 4px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  z-index: 1200;
  background: var(--accent-1);
  color: #0A192F;
  padding: 0.6rem 1.2rem;
  border-radius: 6px;
  font-weight: 700;
  transition: top 0.2s ease;
}

.skip-link:focus {
  top: 1rem;
  color: #0A192F;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 25, 47, 0.84);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
}

.scroll-progress {
  position: absolute;
  top: 0;
  left: 0;
  height: 3px;
  width: 0;
  background: linear-gradient(90deg, var(--accent-1), var(--accent-2), var(--accent-3));
  box-shadow: 0 0 14px rgba(0, 255, 163, 0.55);
  z-index: 120;
  transition: width 0.1s linear;
}

.site-header__inner {
  position: relative;
  max-width: var(--max-w);
  margin-inline: auto;
  padding: 1.4rem 1.5rem 0.85rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.8rem;
}

.site-brand__link {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-decoration: none;
  color: inherit;
}

.site-brand__name {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 2.9rem);
  line-height: 0.9;
  letter-spacing: 0.02em;
  color: var(--text-strong);
  text-transform: uppercase;
  text-shadow: 0 0 18px rgba(0, 255, 163, 0.25);
}

.site-brand__highlight {
  color: var(--accent-3);
  font-style: italic;
}

.site-brand__tag {
  font-size: 0.68rem;
  letter-spacing: 0.42em;
  text-transform: uppercase;
  color: var(--text-dim);
  margin-top: 0.3rem;
  text-decoration: none;
}

.site-nav {
  width: 100%;
}

.nav-list {
  list-style: none;
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.1rem 0.4rem;
}

.nav-item {
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-link {
  position: relative;
  display: block;
  padding: 0.4rem 0.95rem;
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  text-decoration: none;
  white-space: nowrap;
  border-radius: 6px;
  transition: color 0.25s ease, background-color 0.25s ease;
}

.nav-link::after {
  content: '';
  position: absolute;
  left: 15%;
  right: 15%;
  bottom: 4px;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-1), var(--accent-2));
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 0.3s ease;
}

.nav-link:hover,
.nav-link:focus-visible {
  color: var(--text-strong);
  background: rgba(0, 255, 163, 0.06);
}

.nav-link:hover::after,
.nav-link:focus-visible::after {
  transform: scaleX(1);
}

.nav-link[aria-current="page"] {
  color: var(--accent-3);
}

.nav-link[aria-current="page"]::after {
  transform: scaleX(1);
  background: linear-gradient(90deg, var(--accent-3), var(--accent-2));
}

.nav-toggle {
  display: none;
}

.site-footer {
  flex-shrink: 0;
  background: var(--bg-ink);
  color: var(--text-dim);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  font-size: 0.9rem;
}

.site-footer__inner {
  max-width: var(--max-w);
  margin-inline: auto;
  padding: clamp(2.5rem, 6vw, 4rem) 1.5rem 2rem;
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 0.8fr);
  gap: 3rem 4rem;
  align-items: start;
}

.footer-brand__name {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3rem);
  color: var(--text-strong);
  margin: 0;
  text-shadow: 0 0 16px rgba(255, 215, 0, 0.15);
}

.footer-brand__tagline {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: var(--accent-3);
  margin: 0.5rem 0 0;
}

.footer-brand__desc {
  max-width: 46ch;
  margin-top: 0.75rem;
  color: var(--text-dim);
}

.footer-links {
  display: grid;
  justify-items: start;
  gap: 0.7rem;
}

.footer-links__item {
  color: var(--text-dim);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.footer-links__item:hover,
.footer-links__item:focus-visible {
  color: var(--accent-1);
  border-bottom-color: var(--accent-1);
}

.site-footer__legal {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(0, 0, 0, 0.2);
  padding: 1.25rem 0;
}

.site-footer__legal-inner {
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: 1.5rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 2rem;
  align-items: center;
}

.footer-legal__line {
  margin: 0;
  font-size: 0.78rem;
  opacity: 0.65;
}

.site-footer__legal .footer-legal__line:first-child {
  opacity: 0.9;
  color: var(--text-dim);
}

.back-top {
  position: fixed;
  right: 1.25rem;
  bottom: 1.25rem;
  z-index: 90;
  width: 48px;
  height: 48px;
  border: none;
  border-radius: 12px;
  background: linear-gradient(145deg, var(--accent-3), #d4a800);
  color: #0A192F;
  font-size: 1.4rem;
  font-weight: 700;
  line-height: 1;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(255, 215, 0, 0.3);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translateY(8px);
  transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s ease;
}

.back-top.is-visible {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translateY(0);
}

.back-top:hover,
.back-top:focus-visible {
  transform: translateY(-4px);
  box-shadow: 0 8px 28px rgba(255, 215, 0, 0.4);
}

.container {
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: 1.5rem;
}

.section {
  padding-block: clamp(3rem, 7vw, 5.5rem);
}

.section--skew {
  position: relative;
}

.section--skew::before {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  background: linear-gradient(135deg, rgba(17, 34, 64, 0.9), rgba(26, 26, 46, 0.95));
  clip-path: polygon(0 4%, 100% 0, 100% 96%, 0 100%);
}

.section__label {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  font-weight: 700;
  color: var(--accent-1);
  font-size: 0.8rem;
}

.section__label::before {
  content: '';
  width: 34px;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-1), transparent);
  transform: skewX(-20deg);
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1.25rem;
}

.panel {
  position: relative;
  overflow: hidden;
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius);
  padding: clamp(1.25rem, 3vw, 2rem);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.25);
}

.panel::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-1), var(--accent-2), transparent);
  opacity: 0.7;
}

.tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  padding: 0.25rem 0.7rem;
  border-radius: 999px;
  color: var(--accent-2);
  background: rgba(123, 47, 255, 0.12);
  border: 1px solid rgba(123, 47, 255, 0.35);
  text-transform: uppercase;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.65rem 1.4rem;
  font-family: inherit;
  font-weight: 700;
  font-size: 0.95rem;
  border-radius: 8px;
  border: 1px solid transparent;
  background: var(--bg-2);
  color: var(--text-strong);
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease, color 0.2s ease;
}

.btn:hover,
.btn:focus-visible {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
  color: var(--text-strong);
}

.btn--primary {
  background: linear-gradient(135deg, var(--accent-1), #00d97e);
  color: #0A192F;
  border-color: rgba(0, 255, 163, 0.4);
  box-shadow: 0 0 20px rgba(0, 255, 163, 0.25);
}

.btn--primary:hover,
.btn--primary:focus-visible {
  color: #0A192F;
  box-shadow: 0 0 30px rgba(0, 255, 163, 0.35);
}

.btn--ghost {
  background: transparent;
  border-color: rgba(245, 240, 230, 0.25);
  color: var(--text);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  border-color: var(--accent-1);
  color: var(--accent-1);
  box-shadow: none;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-bottom: 1.5rem;
}

.breadcrumb ol,
.breadcrumb ul {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  list-style: none;
  gap: 0.25rem;
}

.breadcrumb li + li::before {
  content: '/';
  margin-inline: 0.25rem;
  color: rgba(255, 255, 255, 0.3);
}

.breadcrumb a {
  color: var(--text-dim);
  text-decoration: none;
}

.breadcrumb a:hover,
.breadcrumb a:focus-visible {
  color: var(--accent-1);
}

.toc {
  position: sticky;
  top: calc(var(--header-h) + 1rem);
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius);
  padding: 1.25rem;
  max-height: calc(100vh - 120px);
  overflow-y: auto;
}

.toc__link {
  display: block;
  padding: 0.35rem 0.6rem;
  color: var(--text-dim);
  text-decoration: none;
  border-left: 2px solid rgba(255, 255, 255, 0.1);
  font-size: 0.85rem;
  transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

.toc__link:hover,
.toc__link:focus-visible {
  color: var(--accent-1);
  background: rgba(0, 255, 163, 0.05);
}

.toc__link--active,
.toc__link[aria-current="location"] {
  color: var(--accent-3);
  border-left-color: var(--accent-3);
}

.timeline {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 12px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--accent-1), var(--accent-2), transparent);
}

.timeline__item {
  position: relative;
  padding-left: 3.2rem;
  padding-bottom: 2.5rem;
}

.timeline__item:last-child {
  padding-bottom: 0;
}

.timeline__dot {
  position: absolute;
  left: 4px;
  top: 0.4rem;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--bg-ink);
  border: 3px solid var(--accent-1);
  box-shadow: 0 0 12px rgba(0, 255, 163, 0.5);
}

[data-reveal] {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

[data-reveal].is-visible,
[data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

@media (max-width: 767px) {
  .site-header__inner {
    padding: 0.8rem 1rem 0.65rem;
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
    gap: 0;
  }

  .site-brand__name {
    font-size: clamp(1.5rem, 6vw, 2rem);
  }

  .site-brand__tag {
    display: none;
  }

  .nav-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: 5px;
    width: 44px;
    height: 44px;
    padding: 0;
    background: rgba(17, 34, 64, 0.6);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 10px;
    cursor: pointer;
    color: var(--accent-1);
    transition: border-color 0.2s ease, background 0.2s ease;
  }

  .nav-toggle:hover,
  .nav-toggle:focus-visible {
    border-color: var(--accent-1);
    background: rgba(0, 255, 163, 0.06);
    outline: none;
  }

  .nav-toggle__bar {
    display: block;
    width: 20px;
    height: 2px;
    background: currentColor;
    border-radius: 2px;
    transition: transform 0.25s ease, opacity 0.25s ease;
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
    opacity: 0;
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }

  .site-nav {
    display: none;
    position: absolute;
    top: calc(100% + 0px);
    left: 0;
    right: 0;
    background: rgba(10, 25, 47, 0.98);
    border-bottom: 1px solid rgba(0, 255, 163, 0.15);
    box-shadow: 0 20px 30px rgba(0, 0, 0, 0.4);
    padding: 0.5rem 0 0.75rem;
  }

  .site-nav[data-open] {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .nav-link {
    padding: 0.8rem 1.2rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: 0;
    white-space: normal;
  }

  .nav-link::after {
    display: none;
  }

  .nav-link:hover,
  .nav-link:focus-visible {
    background: rgba(0, 255, 163, 0.08);
  }

  .nav-link[aria-current="page"] {
    background: rgba(255, 215, 0, 0.08);
  }

  .site-footer__inner {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .grid {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.001s !important;
    transition-duration: 0.001s !important;
  }

  [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .scroll-progress,
  .back-top,
  .nav-toggle__bar,
  .nav-link::after,
  .btn,
  .skip-link {
    transition: none;
  }
}