:root {
  --c-bg: #0B1B2F;
  --c-primary: #B14EFF;
  --c-cyan: #00F0FF;
  --c-teal: #005F6A;
  --c-wine: #7A2048;
  --c-indigo: #3D2E88;
  --c-ink: #1A1A1A;
  --c-paper: #F5F2EB;
  --gradient-line: linear-gradient(90deg, var(--c-cyan), var(--c-primary));
  --font-sans: "Noto Sans SC", "Source Han Sans SC", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, "Courier New", monospace;
  --max-w: 1200px;
}

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

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 1rem; }

body {
  background-color: var(--c-bg);
  background-image:
    linear-gradient(rgba(0, 240, 255, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(177, 78, 255, 0.035) 1px, transparent 1px);
  background-size: 28px 28px;
  color: var(--c-paper);
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.75;
}

h1, h2, h3, h4 { color: var(--c-paper); font-weight: 900; line-height: 1.25; margin-bottom: 1rem; }
h1 { font-size: 2rem; }
h2 { font-size: 1.6rem; }
h3 { font-size: 1.28rem; }
p { color: rgba(245, 242, 235, 0.85); }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
img, svg, video { display: block; max-width: 100%; height: auto; }
button { background: none; border: 0; color: inherit; cursor: pointer; font: inherit; }
input { font: inherit; }
[hidden] { display: none !important; }
::selection { background: var(--c-primary); color: var(--c-paper); }
:focus-visible { outline: 2px solid var(--c-cyan); outline-offset: 3px; }

.container { width: min(100% - 2rem, var(--max-w)); margin-inline: auto; }
.mono { font-family: var(--font-mono); }

.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;
}

.skip-link {
  position: fixed; top: -100px; left: 1rem; z-index: 3000;
  padding: 0.55rem 1.1rem; background: var(--c-cyan); color: var(--c-ink);
  font-weight: 700; font-size: 0.875rem;
  box-shadow: 0 0 0 4px rgba(0, 240, 255, 0.25);
  transition: top 0.2s ease;
}
.skip-link:focus { top: 1rem; }

.progress-bar {
  position: fixed; top: 0; left: 0; z-index: 2500;
  height: 3px; width: 0; background: var(--gradient-line); pointer-events: none;
}

#main-content { scroll-margin-top: 1rem; }
#main-content:focus { outline: none; }
.page-main { padding-block: 2.5rem 4rem; min-height: 50vh; }

.breadcrumbs {
  display: flex; flex-wrap: wrap; align-items: center; gap: 0.4rem;
  margin-bottom: 2rem; font-family: var(--font-mono); font-size: 0.75rem;
  letter-spacing: 0.08em; color: rgba(245, 242, 235, 0.55);
}
.breadcrumbs__sep { color: var(--c-primary); }
.breadcrumbs a:hover { color: var(--c-cyan); }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 0.5rem;
  padding: 0.65rem 1.4rem; background: var(--c-primary); color: #ffffff;
  font-weight: 700; letter-spacing: 0.08em;
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 10px, 100% 100%, 10px 100%, 0 calc(100% - 10px));
  transition: background 0.2s ease, color 0.2s ease;
}
.btn:hover { background: var(--c-cyan); color: var(--c-ink); }
.btn--ghost { background: transparent; border: 1px solid var(--c-primary); color: var(--c-primary); }
.btn--ghost:hover { background: rgba(177, 78, 255, 0.15); border-color: var(--c-cyan); color: var(--c-cyan); }

.section-index { display: block; margin-bottom: 2.5rem; padding-left: 1.25rem; border-left: 4px solid var(--c-primary); }
.section-index__kicker { display: block; font-family: var(--font-mono); font-size: 0.7rem; letter-spacing: 0.25em; color: var(--c-cyan); margin-bottom: 0.35rem; }
.section-index h1, .section-index h2 { margin-bottom: 0.5rem; }
.section-index p { max-width: 60ch; color: rgba(245, 242, 235, 0.7); }

.rule {
  display: flex; align-items: center; gap: 0.75rem; margin-block: 2rem;
  font-family: var(--font-mono); font-size: 0.7rem; letter-spacing: 0.25em; color: var(--c-primary);
}
.rule::after { content: ""; flex: 1; height: 1px; background: linear-gradient(90deg, rgba(177, 78, 255, 0.6), rgba(0, 240, 255, 0.15)); }

.card {
  padding: 1.5rem;
  background: linear-gradient(160deg, rgba(61, 46, 136, 0.55), rgba(0, 95, 106, 0.35));
  border: 1px solid rgba(177, 78, 255, 0.3);
  clip-path: polygon(0 0, calc(100% - 14px) 0, 100% 14px, 100% 100%, 14px 100%, 0 calc(100% - 14px));
}
.card__index { display: block; font-family: var(--font-mono); font-size: 0.75rem; letter-spacing: 0.15em; color: var(--c-cyan); margin-bottom: 0.5rem; }
.card h3 { margin-bottom: 0.5rem; }
.card p { font-size: 0.9rem; color: rgba(245, 242, 235, 0.7); }

.tone-block { padding: 2rem; color: var(--c-paper); clip-path: polygon(0 0, calc(100% - 22px) 0, 100% 22px, 100% 100%, 22px 100%, 0 calc(100% - 22px)); }
.tone-block--teal { background: var(--c-teal); }
.tone-block--wine { background: var(--c-wine); }
.tone-block--indigo { background: var(--c-indigo); }

.tag {
  display: inline-block; padding: 0.2em 0.7em; border: 1px solid rgba(0, 240, 255, 0.4);
  background: rgba(0, 240, 255, 0.06); color: var(--c-cyan);
  font-family: var(--font-mono); font-size: 0.7rem; letter-spacing: 0.15em;
}
.tag--hot { border-color: rgba(177, 78, 255, 0.55); background: rgba(177, 78, 255, 0.1); color: var(--c-primary); }

.stat { font-family: var(--font-mono); font-size: 1.6rem; line-height: 1.2; color: var(--c-cyan); }

.callout {
  padding: 1rem 1.25rem; border: 1px solid rgba(0, 240, 255, 0.3);
  border-left: 4px solid var(--c-cyan); background: rgba(0, 240, 255, 0.06);
  font-size: 0.875rem; color: rgba(245, 242, 235, 0.85);
}

.chapter { display: grid; gap: 0.75rem; padding-block: 1.5rem; border-bottom: 1px solid rgba(177, 78, 255, 0.25); }
.chapter__head { display: flex; align-items: baseline; gap: 1rem; }
.chapter__no { font-family: var(--font-mono); font-size: 0.75rem; color: var(--c-primary); }

.grid { display: grid; gap: 1.5rem; }
@media (min-width: 768px) {
  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 1024px) {
  .grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

.visual-frame {
  position: relative; overflow: hidden; aspect-ratio: 16 / 10;
  background:
    radial-gradient(circle at 72% 28%, rgba(0, 240, 255, 0.4), transparent 52%),
    radial-gradient(circle at 18% 82%, rgba(177, 78, 255, 0.5), transparent 46%),
    linear-gradient(135deg, var(--c-indigo), var(--c-teal) 66%, var(--c-primary));
  clip-path: polygon(0 0, calc(100% - 30px) 0, 100% 30px, 100% 100%, 30px 100%, 0 calc(100% - 30px));
}
.visual-frame::before {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(transparent 92%, rgba(245, 242, 235, 0.06) 92%);
  background-size: 100% 26px; mix-blend-mode: overlay;
}
.visual-frame--wide { aspect-ratio: 21 / 9; }
.visual-frame--tall { aspect-ratio: 4 / 5; }
.visual-frame--narrow { aspect-ratio: 3 / 4; }

.site-header { position: relative; background: var(--c-bg); border-bottom: 1px solid rgba(177, 78, 255, 0.35); }
.site-header::after { content: ""; display: block; height: 2px; background: var(--gradient-line); }

.site-header__topbar { background: linear-gradient(90deg, var(--c-indigo) 0%, var(--c-teal) 100%); border-bottom: 1px solid rgba(0, 240, 255, 0.25); }
.site-header__topbar-inner { display: flex; align-items: center; justify-content: space-between; gap: 1rem; min-height: 2.4rem; }
.site-header__meta { font-size: 0.7rem; letter-spacing: 0.2em; text-transform: uppercase; color: rgba(245, 242, 235, 0.85); }
.site-header__actions { display: flex; align-items: center; gap: 0.4rem; }

.search-toggle {
  display: inline-flex; align-items: center; gap: 0.45rem;
  padding: 0.3rem 0.75rem; border: 1px solid rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.06); font-family: var(--font-mono);
  font-size: 0.7rem; letter-spacing: 0.12em; color: var(--c-paper);
  transition: background 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}
.search-toggle:hover { border-color: var(--c-cyan); background: rgba(0, 240, 255, 0.14); color: var(--c-cyan); }
.search-toggle[aria-expanded="true"] { border-color: var(--c-primary); background: rgba(177, 78, 255, 0.16); }
.search-toggle__glyph { position: relative; display: inline-block; width: 0.7em; height: 0.7em; border: 1.5px solid currentColor; border-radius: 50%; }
.search-toggle__glyph::after {
  content: ""; position: absolute; right: -0.45em; bottom: -0.05em;
  width: 0.5em; height: 1.5px; background: currentColor;
  transform: rotate(45deg); transform-origin: left center;
}

.nav-toggle { display: none; flex-direction: column; align-items: center; justify-content: center; gap: 0.28rem; width: 2.4rem; height: 2.4rem; border: 1px solid rgba(255, 255, 255, 0.2); background: rgba(255, 255, 255, 0.06); }
.nav-toggle:hover { border-color: var(--c-cyan); }
.nav-toggle__bar { display: block; width: 1.1rem; height: 2px; background: var(--c-paper); transition: transform 0.2s ease, opacity 0.2s ease; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) { transform: translateY(0.43rem) 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(-0.43rem) rotate(-45deg); }

.site-header__inner { padding-block: 0; }
.masthead { padding: 2rem 0 1.5rem; text-align: center; }
.masthead__kicker { display: inline-flex; align-items: center; gap: 0.5rem; margin-bottom: 0.75rem; font-size: 0.68rem; letter-spacing: 0.28em; text-transform: uppercase; color: var(--c-cyan); }
.masthead__kicker-dot { display: inline-block; width: 6px; height: 6px; background: var(--c-primary); transform: rotate(45deg); }
.masthead__brand { display: inline-flex; align-items: center; gap: 0.9rem; }
.masthead__mark {
  display: inline-flex; align-items: center; justify-content: center;
  width: 4.2rem; height: 3.4rem; background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-indigo) 100%);
  color: #ffffff; font-family: var(--font-mono); font-size: 1.5rem; font-weight: 700; letter-spacing: 0.02em;
  clip-path: polygon(0 0, 85% 0, 100% 15%, 100% 100%, 15% 100%, 0 85%);
  box-shadow: 0 0 24px rgba(177, 78, 255, 0.35);
}
.masthead__title { color: var(--c-paper); font-size: 2.6rem; font-weight: 900; line-height: 1; letter-spacing: 0.06em; }
.masthead__sub { margin-top: 0.5rem; font-size: 0.78rem; letter-spacing: 0.32em; color: rgba(245, 242, 235, 0.68); }
.masthead__tags { margin-top: 1rem; font-size: 0.7rem; letter-spacing: 0.18em; color: var(--c-primary); }

.main-nav {
  display: block;
  border-top: 1px solid rgba(177, 78, 255, 0.3);
  border-bottom: 1px solid rgba(0, 240, 255, 0.3);
  background: linear-gradient(90deg, rgba(61, 46, 136, 0.32), rgba(0, 95, 106, 0.22));
}
.main-nav__list { display: flex; flex-wrap: wrap; justify-content: center; }
.main-nav__item { position: relative; }
.main-nav__link {
  position: relative; display: inline-flex; align-items: baseline; gap: 0.5rem;
  padding: 0.8rem 1.15rem; color: var(--c-paper); font-weight: 600; letter-spacing: 0.1em;
  transition: background 0.2s ease, color 0.2s ease;
}
.main-nav__index { font-family: var(--font-mono); font-size: 0.68rem; letter-spacing: 0.05em; color: var(--c-primary); transition: color 0.2s ease; }
.main-nav__link:hover { background: rgba(177, 78, 255, 0.18); color: var(--c-cyan); }
.main-nav__link:hover .main-nav__index { color: var(--c-cyan); }
.main-nav__link[aria-current="page"] { background: var(--c-primary); color: #ffffff; }
.main-nav__link[aria-current="page"] .main-nav__index { color: #ffffff; }
.main-nav__link[aria-current="page"]::after { content: ""; position: absolute; left: 12%; right: 12%; bottom: 0; height: 3px; background: var(--c-cyan); }
.main-nav__item.is-filtered { display: none; }

.search-panel {
  display: none; align-items: center; flex-wrap: wrap; gap: 0.6rem 1rem;
  padding: 0.8rem 1rem; border-bottom: 1px solid rgba(0, 240, 255, 0.28);
  background: rgba(0, 240, 255, 0.07);
}
.search-panel[data-open] { display: flex; }
.search-panel__label { font-size: 0.68rem; letter-spacing: 0.2em; text-transform: uppercase; color: var(--c-cyan); }
.search-panel__input {
  flex: 1 1 12rem; min-width: 10rem; padding: 0.45rem 0.7rem;
  border: 1px solid rgba(245, 242, 235, 0.28); background: rgba(11, 27, 47, 0.85);
  color: var(--c-paper); font-family: var(--font-mono); font-size: 0.875rem;
}
.search-panel__input::placeholder { color: rgba(245, 242, 235, 0.4); }
.search-panel__input:focus-visible { border-color: var(--c-cyan); }
.search-panel__kbd { padding: 0.12rem 0.5rem; border: 1px solid rgba(245, 242, 235, 0.3); font-size: 0.68rem; color: rgba(245, 242, 235, 0.6); }
.search-panel__empty { flex-basis: 100%; font-size: 0.72rem; letter-spacing: 0.1em; color: var(--c-primary); }

.site-footer {
  position: relative; margin-top: 4rem;
  background: linear-gradient(180deg, rgba(61, 46, 136, 0.28), transparent 40%), var(--c-bg);
  border-top: 1px solid rgba(0, 240, 255, 0.35);
}
.site-footer::before { content: ""; position: absolute; top: -1px; left: 0; width: 42%; height: 3px; background: var(--gradient-line); }
.site-footer__inner { display: grid; gap: 2rem; padding-block: 3rem 2.25rem; }
.site-footer__logo { display: inline-flex; align-items: center; gap: 0.55rem; font-size: 1.5rem; font-weight: 900; letter-spacing: 0.05em; color: var(--c-paper); }
.site-footer__logo-mark {
  display: inline-flex; align-items: center; justify-content: center;
  width: 2.4rem; height: 2rem; background: linear-gradient(135deg, var(--c-primary), var(--c-indigo));
  color: #ffffff; font-family: var(--font-mono); font-size: 0.85rem; font-weight: 700;
  clip-path: polygon(0 0, 80% 0, 100% 20%, 100% 100%, 20% 100%, 0 80%);
}
.site-footer__tagline { margin-top: 0.6rem; font-size: 0.85rem; color: rgba(245, 242, 235, 0.75); letter-spacing: 0.06em; }
.site-footer__trust { margin-top: 1rem; padding-left: 0.8rem; border-left: 2px solid var(--c-teal); font-size: 0.78rem; line-height: 1.7; color: rgba(245, 242, 235, 0.58); }
.site-footer__heading { margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 1px solid rgba(0, 240, 255, 0.22); font-size: 0.68rem; font-weight: 400; letter-spacing: 0.25em; text-transform: uppercase; color: var(--c-cyan); }
.site-footer__col ul li { margin-bottom: 0.5rem; }
.site-footer__col a { font-size: 0.875rem; color: rgba(245, 242, 235, 0.8); transition: color 0.2s ease, padding-left 0.2s ease; }
.site-footer__col a:hover { color: var(--c-primary); padding-left: 0.3rem; }
.site-footer__contact li { display: flex; flex-direction: column; gap: 0.1rem; margin-bottom: 0.85rem; font-size: 0.85rem; color: rgba(245, 242, 235, 0.8); }
.site-footer__label { font-size: 0.62rem; letter-spacing: 0.2em; color: var(--c-primary); }
.site-footer__bottom { border-top: 1px solid rgba(245, 242, 235, 0.12); background: rgba(0, 0, 0, 0.28); }
.site-footer__bottom-inner {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: 0.8rem 1.5rem; padding-block: 1rem 1.1rem;
  font-size: 0.78rem; color: rgba(245, 242, 235, 0.68);
}
.site-footer__copyright { color: inherit; }
.site-footer__icp { font-size: 0.72rem; color: rgba(0, 240, 255, 0.75); }

.back-to-top {
  display: inline-flex; align-items: center; gap: 0.4rem;
  padding: 0.35rem 0.8rem; border: 1px solid rgba(0, 240, 255, 0.35);
  background: rgba(0, 240, 255, 0.06); font-family: var(--font-mono);
  font-size: 0.72rem; letter-spacing: 0.1em; color: var(--c-cyan);
  transition: background 0.2s ease, color 0.2s ease;
}
.back-to-top:hover { background: rgba(0, 240, 255, 0.18); color: var(--c-paper); }

@media (max-width: 767px) {
  .nav-toggle { display: inline-flex; }
  .site-header__topbar-inner { min-height: 2.75rem; }
  .search-toggle { padding: 0.3rem 0.6rem; }
  .masthead { padding-top: 1.5rem; }
  .masthead__title { font-size: 2rem; }
  .masthead__mark { width: 3.4rem; height: 2.9rem; font-size: 1.2rem; }
  .main-nav { display: none; }
  .main-nav[data-open] { display: block; }
  .main-nav__list { flex-direction: column; }
  .main-nav__link { width: 100%; padding: 0.85rem 1.25rem; border-bottom: 1px solid rgba(177, 78, 255, 0.14); }
  .main-nav__link[aria-current="page"]::after { display: none; }
  .site-footer__inner { grid-template-columns: 1fr; padding-top: 2.5rem; }
  .site-footer__bottom-inner { justify-content: center; text-align: center; }
  .site-footer__bottom-inner .back-to-top { order: -1; }
}

@media (min-width: 768px) {
  .site-footer__inner { grid-template-columns: 2fr 1fr 1fr 1.4fr; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
}