/* ===== RESET & BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { min-height: 100vh; background: #0A1F3F; color: #E0E6F0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; font-size: 16px; line-height: 1.6; -webkit-font-smoothing: antialiased; }
img { max-width: 100%; display: block; }
a { color: #E0E6F0; text-decoration: none; transition: color 0.2s, border-color 0.2s, box-shadow 0.2s; }
a:hover { color: #39FF14; }
ul { list-style: none; }
:focus-visible { outline: 2px solid #39FF14; outline-offset: 2px; }
::selection { background: #9B59B6; color: #FFF; }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; } }

/* ===== CSS VARIABLES ===== */
:root {
  --color-primary: #0A1F3F;
  --color-accent1: #39FF14;
  --color-accent2: #9B59B6;
  --color-surface: #121C2A;
  --color-text: #E0E6F0;
  --color-text-secondary: #8899B0;
  --color-border: #2A3A5A;
  --color-success: #39FF14;
  --color-error: #E74C3C;
  --rail-width: 200px;
  --header-z: 1000;
  --font-heading: "Arial Black", "Impact", "Franklin Gothic Heavy", sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --container-max: 1200px;
  --border-radius: 2px;
  --transition-fast: 0.15s;
  --transition-base: 0.3s;
}

/* ===== LAYOUT: SIDE RAIL ===== */
body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}
#main-content {
  flex: 1;
  margin-left: var(--rail-width);
  width: calc(100% - var(--rail-width));
  padding: var(--spacing-lg) var(--spacing-xl);
  max-width: calc(var(--container-max) + var(--rail-width));
}
@media (max-width: 899px) {
  #main-content {
    margin-left: 0;
    width: 100%;
    padding: var(--spacing-md);
    padding-top: 70px;
  }
}

/* ===== SKIP LINK ===== */
.skip-link {
  position: fixed;
  top: -100px;
  left: var(--spacing-md);
  z-index: calc(var(--header-z) + 10);
  background: #39FF14;
  color: #0A1F3F;
  padding: var(--spacing-sm) var(--spacing-md);
  font-weight: 700;
  font-size: 0.875rem;
  border-radius: var(--border-radius);
  transition: top var(--transition-base);
}
.skip-link:focus {
  top: var(--spacing-sm);
}

/* ===== BRAND RAIL (HEADER) ===== */
.brand-rail {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--rail-width);
  height: 100vh;
  z-index: var(--header-z);
  display: flex;
  flex-direction: column;
  background: transparent;
  border-right: 1px solid transparent;
  transition: background var(--transition-base), border-color var(--transition-base);
  padding: var(--spacing-lg) var(--spacing-md);
  backdrop-filter: blur(0px);
}
.brand-rail[data-scrolled] {
  background: var(--color-primary);
  border-right-color: var(--color-border);
  backdrop-filter: blur(4px);
}
.brand-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--spacing-xl);
}
.brand-logo {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  letter-spacing: 0.08em;
  color: #fff;
  text-transform: uppercase;
  line-height: 1.2;
  border-bottom: 2px solid #39FF14;
  padding-bottom: 2px;
}
.brand-logo:hover {
  color: #39FF14;
  border-bottom-color: #39FF14;
}
.search-btn {
  background: none;
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  border-radius: var(--border-radius);
  transition: color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.search-btn:hover {
  color: #39FF14;
  border-color: #39FF14;
  box-shadow: 0 0 8px rgba(57,255,20,0.3);
}
.search-icon::before {
  content: "⌕";
  font-size: 1.2rem;
  font-weight: 700;
}

/* ===== NAVIGATION ===== */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
}
.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  width: 24px;
  height: 2px;
  background: #E0E6F0;
  transition: transform var(--transition-base);
}
.hamburger {
  position: relative;
}
.hamburger::before,
.hamburger::after {
  content: "";
  position: absolute;
  left: 0;
}
.hamburger::before { top: -7px; }
.hamburger::after { top: 7px; }
[data-open] .hamburger { transform: rotate(45deg); }
[data-open] .hamburger::before { transform: rotate(90deg); top: 0; }
[data-open] .hamburger::after { opacity: 0; }

.nav-container {
  flex: 1;
}
.nav-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}
.nav-list a {
  display: block;
  padding: var(--spacing-sm) var(--spacing-sm);
  font-family: var(--font-heading);
  font-size: 0.95rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  border-left: 2px solid transparent;
  transition: color var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
  font-weight: 700;
}
.nav-list a:hover {
  color: #39FF14;
  border-left-color: #39FF14;
  background: rgba(57,255,20,0.05);
}
.nav-list a[aria-current="page"] {
  color: #fff;
  border-left-color: #39FF14;
  background: rgba(57,255,20,0.08);
  box-shadow: inset 3px 0 0 #39FF14;
}

.brand-footer {
  margin-top: auto;
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border);
}
.rail-label {
  font-size: 0.625rem;
  letter-spacing: 0.15em;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  opacity: 0.6;
}

/* ===== MOBILE NAV ===== */
@media (max-width: 899px) {
  .brand-rail {
    width: 100%;
    height: auto;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: transparent;
    border-right: none;
    border-bottom: 1px solid transparent;
    backdrop-filter: blur(0px);
  }
  .brand-rail[data-scrolled] {
    background: var(--color-primary);
    border-bottom-color: var(--color-border);
    backdrop-filter: blur(4px);
  }
  .brand-header {
    width: 100%;
    margin-bottom: 0;
    display: flex;
    align-items: center;
    justify-content: space-between;
  }
  .nav-toggle {
    display: block;
    order: 3;
  }
  .search-btn {
    order: 2;
    margin-right: var(--spacing-sm);
  }
  .brand-logo {
    order: 1;
    font-size: 1.25rem;
  }
  .nav-container {
    order: 4;
    width: 100%;
    flex: 0 0 100%;
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-base), padding var(--transition-base);
    padding: 0;
  }
  .nav-container[data-open] {
    max-height: 500px;
    padding: var(--spacing-md) 0;
  }
  .nav-list {
    flex-direction: column;
    gap: 0;
  }
  .nav-list a {
    font-size: 0.9rem;
    padding: var(--spacing-sm) var(--spacing-sm);
    border-left: 2px solid transparent;
  }
  .brand-footer {
    display: none;
  }
}

/* ===== FOOTER ===== */
.site-footer {
  background: var(--color-primary);
  border-top: 1px solid var(--color-border);
  margin-left: var(--rail-width);
  padding: var(--spacing-xl) var(--spacing-xl) var(--spacing-lg);
  color: var(--color-text-secondary);
  font-size: 0.875rem;
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--spacing-lg);
  max-width: var(--container-max);
  margin: 0 auto;
}
.footer-brand {
  flex: 1 1 220px;
}
.footer-logo {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  letter-spacing: 0.06em;
  color: #fff;
  text-transform: uppercase;
  border-bottom: 2px solid #39FF14;
  padding-bottom: 2px;
}
.footer-logo:hover {
  color: #39FF14;
  border-bottom-color: #39FF14;
}
.footer-tagline {
  margin-top: var(--spacing-sm);
  font-size: 0.8rem;
  opacity: 0.7;
  color: var(--color-text-secondary);
}
.footer-links {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  flex: 1 1 160px;
}
.footer-links a {
  color: var(--color-text-secondary);
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}
.footer-links a:hover {
  color: #39FF14;
  border-bottom-color: #39FF14;
}
.footer-info {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  flex: 1 1 200px;
  font-size: 0.8rem;
  opacity: 0.7;
}
.footer-bottom {
  max-width: var(--container-max);
  margin: var(--spacing-lg) auto 0;
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border);
  text-align: center;
  font-size: 0.75rem;
  opacity: 0.6;
}
@media (max-width: 899px) {
  .site-footer {
    margin-left: 0;
    padding: var(--spacing-lg) var(--spacing-md);
  }
  .footer-inner {
    flex-direction: column;
    gap: var(--spacing-md);
  }
}

/* ===== COMMON COMPONENTS ===== */
/* Primary Button */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  font-family: var(--font-heading);
  font-size: 0.9rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: #0A1F3F;
  background: #39FF14;
  border: 2px solid #39FF14;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: background var(--transition-fast), box-shadow var(--transition-fast), color var(--transition-fast);
  font-weight: 700;
}
.btn-primary:hover {
  background: transparent;
  color: #39FF14;
  box-shadow: 0 0 16px rgba(57,255,20,0.4);
}

/* Outline Button */
.btn-outline {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  font-family: var(--font-heading);
  font-size: 0.9rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: #39FF14;
  background: transparent;
  border: 2px solid #39FF14;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: background var(--transition-fast), box-shadow var(--transition-fast);
  font-weight: 700;
}
.btn-outline:hover {
  background: rgba(57,255,20,0.1);
  box-shadow: 0 0 12px rgba(57,255,20,0.3);
}

/* Chapter Number */
.chapter-number {
  font-family: var(--font-heading);
  font-size: 4rem;
  line-height: 1;
  letter-spacing: 0.04em;
  color: rgba(57,255,20,0.15);
  -webkit-text-stroke: 1px rgba(57,255,20,0.3);
  user-select: none;
}
@media (min-width: 768px) {
  .chapter-number { font-size: 6rem; }
}

/* Tag Label */
.tag-label {
  display: inline-block;
  padding: 2px 10px;
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 700;
  color: #fff;
  background: var(--color-accent2);
  border-radius: var(--border-radius);
  border: 1px solid rgba(155,89,182,0.4);
}

/* Grid Card */
.grid-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  box-shadow: 0 2px 8px rgba(0,0,0,0.3), inset 0 0 0 1px rgba(57,255,20,0.04);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.grid-card:hover {
  border-color: rgba(57,255,20,0.3);
  box-shadow: 0 4px 16px rgba(0,0,0,0.4), 0 0 12px rgba(57,255,20,0.06);
}

/* Progress Bar (scroll) */
.progress-track {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: #39FF14;
  z-index: calc(var(--header-z) + 20);
  width: 0%;
  transition: width 0.1s linear;
  pointer-events: none;
}
@media (max-width: 899px) {
  .progress-track {
    top: auto;
    bottom: 0;
    height: 3px;
  }
}

/* Breadcrumb (shared) */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
}
.breadcrumb a {
  color: var(--color-text-secondary);
  border-bottom: 1px solid transparent;
}
.breadcrumb a:hover {
  color: #39FF14;
  border-bottom-color: #39FF14;
}
.breadcrumb span {
  color: var(--color-text-secondary);
  opacity: 0.5;
}

/* Content Container (shared) */
.content-container {
  max-width: var(--container-max);
  margin: 0 auto;
}

/* Responsive Grid (shared基础) */
.grid-auto {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--spacing-md);
}

/* Section Divider (斜切装饰) */
.section-divider {
  height: 2px;
  background: linear-gradient(90deg, transparent, #39FF14, transparent);
  margin: var(--spacing-xl) 0;
  opacity: 0.3;
}

/* Focus visible for all interactive */
button:focus-visible,
a:focus-visible,
[tabindex]:focus-visible {
  outline: 2px solid #39FF14;
  outline-offset: 2px;
}

/* ===== UTILITY ===== */
.text-accent { color: #39FF14; }
.text-secondary { color: var(--color-text-secondary); }
.text-center { text-align: center; }
.mt-lg { margin-top: var(--spacing-lg); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); border: 0; }

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
  .brand-rail, .nav-container, .nav-list a, .btn-primary, .btn-outline, .grid-card, .progress-track {
    transition-duration: 0.01ms !important;
  }
}