/* ===== Reset & Variables ===== */
:root {
  --bg-deep: #0B1026;
  --bg-panel: #121A3A;
  --neon-green: #00FF87;
  --electric-orange: #FF6B00;
  --jade: #0F4C5C;
  --garnet: #6B1F3A;
  --indigo: #2D1B4E;
  --text-main: #E6F0FF;
  --text-sub: #A0B0C0;
  --grid-line: #2A3B5C;
  --font-display: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', 'Consolas', 'Liberation Mono', monospace;
  --container-w: 1200px;
  --header-h: 9rem;
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
}

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

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

body {
  background-color: var(--bg-deep);
  color: var(--text-main);
  font-family: var(--font-mono);
  font-size: 1rem;
  line-height: 1.75;
  min-height: 100vh;
  background-image:
    linear-gradient(rgba(42, 59, 92, 0.25) 1px, transparent 1px),
    linear-gradient(90deg, rgba(42, 59, 92, 0.25) 1px, transparent 1px);
  background-size: 40px 40px;
  display: flex;
  flex-direction: column;
}

body > * {
  flex-shrink: 0;
}

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

a {
  color: var(--neon-green);
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
}

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

ul,
ol {
  list-style: none;
}

:focus-visible {
  outline: 3px solid var(--electric-orange);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ===== Typography ===== */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-display);
  font-weight: 900;
  line-height: 1.2;
  text-wrap: balance;
}

p {
  text-wrap: pretty;
}

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

/* ===== Layout Primitives ===== */
.container {
  max-width: var(--container-w);
  margin-inline: auto;
  padding-inline: 1.5rem;
}

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1.5rem;
}

.col-span-4 { grid-column: span 4; }
.col-span-6 { grid-column: span 6; }
.col-span-8 { grid-column: span 8; }
.col-span-12 { grid-column: span 12; }

.section {
  padding-block: 4rem;
  position: relative;
}

/* ===== Skip Link ===== */
.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 2000;
  background: var(--electric-orange);
  color: var(--bg-deep);
  font-family: var(--font-display);
  font-weight: 700;
  padding: 0.5rem 1rem;
  clip-path: polygon(0 0, 100% 0, calc(100% - 8px) 100%, 0 100%);
  transform: translateY(-150%);
  transition: transform 0.3s var(--ease-out);
}

.skip-link:focus-visible {
  transform: translateY(0);
}

/* ===== Scroll Progress ===== */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 4px;
  width: 0%;
  background: linear-gradient(90deg, var(--neon-green), var(--electric-orange));
  z-index: 1500;
  pointer-events: none;
}

/* ===== Header / Masthead ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(11, 16, 38, 0.88);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--grid-line);
  transition: background 0.3s ease;
}

.site-header::after {
  content: '';
  display: block;
  height: 3px;
  background: var(--electric-orange);
  clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%);
}

.header-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding-block: 1rem 0.5rem;
  gap: 0.75rem;
}

.brand-mark {
  display: flex;
  align-items: baseline;
  gap: 0.85rem;
  flex-wrap: wrap;
  justify-content: center;
}

.brand-link {
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
  text-decoration: none;
  color: var(--text-main);
}

.brand-name {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 900;
  letter-spacing: 0.08em;
  background: linear-gradient(180deg, var(--text-main) 40%, rgba(230, 240, 255, 0.7));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-tagline {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-sub);
  letter-spacing: 0.1em;
}

.version-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--bg-deep);
  background: var(--neon-green);
  padding: 0.15rem 0.6rem;
  clip-path: polygon(0 0, 100% 0, calc(100% - 8px) 100%, 0 100%);
  align-self: center;
}

/* ===== Navigation ===== */
.site-nav {
  width: 100%;
}

.nav-list {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2rem;
  padding-bottom: 0.5rem;
}

.nav-link {
  position: relative;
  font-family: var(--font-display);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-main);
  text-decoration: none;
  letter-spacing: 0.05em;
  padding: 0.35rem 0.15rem;
  transition: color 0.2s ease;
}

.nav-link::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  background: var(--neon-green);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s var(--ease-out);
}

.nav-link:hover,
.nav-link:focus-visible {
  color: var(--neon-green);
}

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

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

.nav-link[aria-current="page"]::after {
  background: var(--electric-orange);
  transform: scaleX(1);
}

/* ===== Mobile Nav ===== */
.mobile-nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  background: var(--bg-panel);
  border: 1px solid var(--grid-line);
  cursor: pointer;
}

.nav-toggle-line {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--text-main);
  transition: transform 0.3s var(--ease-out), opacity 0.2s ease;
}

@media (max-width: 768px) {
  .mobile-nav-toggle {
    display: flex;
  }

  .site-nav {
    display: none;
    border-top: 1px solid var(--grid-line);
    margin-top: 0.25rem;
  }

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

  .nav-list {
    flex-direction: column;
    gap: 0;
    padding-block: 0.5rem;
  }

  .nav-link {
    display: block;
    padding: 0.85rem 0;
    text-align: center;
    width: 100%;
  }

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

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

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

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

/* ===== Footer ===== */
.site-footer {
  margin-top: auto;
  background: linear-gradient(180deg, var(--indigo) 0%, #0f0a1f 100%);
  border-top: 2px solid var(--neon-green);
  position: relative;
}

.site-footer::before {
  content: '';
  position: absolute;
  top: -6px;
  left: 0;
  width: 100%;
  height: 6px;
  background: var(--electric-orange);
  clip-path: polygon(0 0, 30% 0, 25% 100%, 0 100%);
}

.footer-inner {
  padding-block: 3rem 1.5rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 3rem;
  padding-bottom: 2rem;
}

.footer-brand {
  display: block;
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 900;
  letter-spacing: 0.06em;
  color: var(--text-main);
}

.footer-slogan {
  color: var(--neon-green);
  font-size: 0.8rem;
  margin-top: 0.25rem;
}

.footer-statement {
  color: var(--text-sub);
  font-size: 0.75rem;
  line-height: 1.6;
  margin-top: 1rem;
  max-width: 36ch;
}

.footer-heading {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--neon-green);
  text-transform: uppercase;
  letter-spacing: 0.15em;
  margin-bottom: 1rem;
  padding-bottom: 0.35rem;
  border-bottom: 1px solid var(--grid-line);
  display: inline-block;
}

.footer-links,
.footer-contact {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-links a,
.footer-contact a {
  color: var(--text-main);
  text-decoration: none;
  font-size: 0.85rem;
  transition: color 0.2s ease, padding-left 0.2s ease;
}

.footer-links a:hover,
.footer-links a:focus-visible,
.footer-contact a:hover,
.footer-contact a:focus-visible {
  color: var(--neon-green);
  padding-left: 4px;
}

.footer-contact li {
  color: var(--text-sub);
  font-size: 0.85rem;
}

.footer-contact li:first-child a,
.footer-contact li:nth-child(2) a {
  color: var(--text-main);
}

.footer-legal {
  border-top: 1px solid var(--grid-line);
  padding-top: 1.5rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.5rem;
  color: var(--text-sub);
  font-size: 0.7rem;
  letter-spacing: 0.03em;
}

/* ===== Buttons ===== */
.btn {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 0.9rem;
  font-weight: 700;
  padding: 0.7rem 1.4rem;
  text-decoration: none;
  border: 2px solid var(--neon-green);
  color: var(--neon-green);
  background: transparent;
  clip-path: polygon(0 0, calc(100% - 12px) 0, 100% 12px, 100% 100%, 0 100%);
  transition: background 0.25s ease, color 0.25s ease, transform 0.25s var(--ease-out);
}

.btn:hover,
.btn:focus-visible {
  background: var(--neon-green);
  color: var(--bg-deep);
  transform: translateY(-2px);
}

.btn-primary {
  background: var(--neon-green);
  color: var(--bg-deep);
}

.btn-primary:hover,
.btn-primary:focus-visible {
  background: transparent;
  color: var(--neon-green);
}

.btn-alert {
  border-color: var(--electric-orange);
  color: var(--electric-orange);
}

.btn-alert:hover,
.btn-alert:focus-visible {
  background: var(--electric-orange);
  color: var(--bg-deep);
}

/* ===== Panels & Cards ===== */
.panel {
  background: var(--bg-panel);
  border: 1px solid var(--grid-line);
  padding: 1.5rem;
  position: relative;
  transition: border-color 0.25s ease, transform 0.25s var(--ease-out);
}

.panel:hover {
  border-color: var(--neon-green);
  transform: translateY(-4px);
}

.panel-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--neon-green);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.5rem;
}

.panel-title {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}

.panel-text {
  color: var(--text-sub);
  font-size: 0.85rem;
  line-height: 1.6;
}

/* ===== Section Index ===== */
.section-index {
  font-family: var(--font-display);
  font-size: 5rem;
  font-weight: 900;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 2px var(--neon-green);
  padding-right: 1rem;
}

.section-index::after {
  content: '';
  display: inline-block;
  width: 60px;
  height: 4px;
  background: var(--electric-orange);
  margin-left: 0.75rem;
  vertical-align: middle;
  clip-path: polygon(0 0, 100% 0, calc(100% - 8px) 100%, 0 100%);
}

/* ===== Breadcrumbs ===== */
.breadcrumbs {
  padding-block: 1rem;
  font-size: 0.8rem;
  color: var(--text-sub);
}

.breadcrumbs a {
  color: var(--neon-green);
  text-decoration: none;
}

.breadcrumbs a:hover {
  text-decoration: underline;
}

.breadcrumbs .separator {
  margin-inline: 0.5rem;
  color: var(--grid-line);
}

/* ===== Tags ===== */
.tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--neon-green);
  background: rgba(0, 255, 135, 0.08);
  border: 1px solid rgba(0, 255, 135, 0.3);
  padding: 0.15rem 0.6rem;
  margin-right: 0.25rem;
  margin-bottom: 0.25rem;
  clip-path: polygon(0 0, 100% 0, calc(100% - 6px) 100%, 0 100%);
}

.tag-alert {
  color: var(--electric-orange);
  border-color: rgba(255, 107, 0, 0.3);
  background: rgba(255, 107, 0, 0.08);
}

/* ===== Back to Top ===== */
.back-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 3rem;
  height: 3rem;
  background: var(--bg-panel);
  border: 1px solid var(--neon-green);
  color: var(--neon-green);
  font-size: 1.4rem;
  line-height: 1;
  display: none;
  place-items: center;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%);
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease, transform 0.2s var(--ease-out);
  z-index: 900;
}

.back-top.is-visible {
  display: grid;
}

.back-top:hover,
.back-top:focus-visible {
  background: var(--neon-green);
  color: var(--bg-deep);
  transform: translateY(-4px);
}

/* ===== Image Placeholder Base ===== */
.figure-block {
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, var(--bg-panel), var(--indigo));
  border: 1px solid var(--grid-line);
  min-height: 220px;
  display: grid;
  place-items: center;
  color: var(--text-sub);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.figure-block::after {
  content: 'DATA_IMG';
  letter-spacing: 0.2em;
  opacity: 0.6;
}

.figure-block[data-fig-label]::before {
  content: attr(data-fig-label);
  position: absolute;
  top: 0.5rem;
  left: 0.5rem;
  font-size: 0.65rem;
  color: var(--neon-green);
  background: rgba(0, 255, 135, 0.1);
  padding: 0.1rem 0.4rem;
  z-index: 1;
}

/* ===== Scroll Reveal ===== */
[data-reveal] {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}

[data-reveal].is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Responsive ===== */
@media (min-width: 769px) and (max-width: 1024px) {
  .header-inner {
    padding-inline: 1rem;
  }

  .nav-list {
    gap: 1rem;
  }

  .nav-link {
    font-size: 0.85rem;
  }

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

  .col-span-8,
  .col-span-6,
  .col-span-4 {
    grid-column: span 12;
  }
}

@media (max-width: 768px) {
  .header-inner {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    padding-block: 0.75rem;
  }

  .brand-mark {
    justify-content: flex-start;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 0.5rem;
  }

  .brand-name {
    font-size: 1.5rem;
  }

  .brand-tagline {
    display: none;
  }

  .site-header {
    position: sticky;
    top: 0;
  }

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

  .footer-legal {
    flex-direction: column;
    align-items: flex-start;
  }

  .section-index {
    font-size: 3.5rem;
  }

  .container {
    padding-inline: 1rem;
  }

  .back-top {
    bottom: 1rem;
    right: 1rem;
    width: 2.5rem;
    height: 2.5rem;
  }
}

/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

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

  .back-top,
  .mobile-nav-toggle .nav-toggle-line {
    transition: none;
  }
}

/* ===== Utility Helpers ===== */
.text-mono { font-family: var(--font-mono); }
.text-heavy { font-family: var(--font-display); font-weight: 900; }
.text-neon { color: var(--neon-green); }
.text-alert { color: var(--electric-orange); }
.text-sub { color: var(--text-sub); }
.bg-jade { background-color: var(--jade); }
.bg-garnet { background-color: var(--garnet); }
.bg-indigo { background-color: var(--indigo); }
.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }
.py-4 { padding-block: 4rem; }
.py-6 { padding-block: 6rem; }