/* ================================================================
   U3-HDXV DOCUMENTATION — SHARED STYLESHEET
   Used by: index.html, template_item.html
   ================================================================ */

/* ============ TOKENS ============ */
:root {
  --bg: #ffffff;
  --bg-soft: #f7f8fa;
  --bg-ink: #0a0a0f;
  --ink: #0a0a0f;
  --ink-soft: #4a4a55;
  --ink-mute: #8a8a95;
  --line: #e8e8ec;
  --line-soft: #f0f0f3;
  --cyan: #00d4ff;
  --cyan-soft: #e6fbff;
  --red: #ff3b30;
  --blue: #0066ff;
  --orange: #ff9500;
  --ease-quiet: cubic-bezier(.22,1,.36,1);
  --ease-precise: cubic-bezier(.4,0,.2,1);
  --ease-emphasis: cubic-bezier(.16,1,.3,1);
}

/* ============ BASE ============ */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Raleway', sans-serif;
  background: var(--bg);
  color: var(--ink);
  font-weight: 400;
  line-height: 1.6;
  overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
::selection { background: var(--cyan); color: var(--bg-ink); }

/* ============ PARTICLE BG ============ */
#particle-canvas {
  position: fixed; inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.55;
}

/* ============ TOP NAV ============ */
.topnav {
  position: fixed; top: 0; left: 0; right: 0;
  z-index: 100;
  display: flex; align-items: center; justify-content: space-between;
  padding: 1.2rem 2rem;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--line);
}
.brand {
  display: flex; align-items: center; gap: 0.6rem;
  font-weight: 700; letter-spacing: -0.02em; font-size: 1.05rem;
}
.brand-mark {
  width: 28px; height: 28px;
  background: var(--bg-ink);
  border-radius: 6px;
  display: grid; place-items: center;
  color: var(--cyan);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem; font-weight: 700;
}
.nav-links { display: flex; gap: 2rem; align-items: center; }
.nav-links a {
  font-size: 0.85rem; color: var(--ink-soft);
  font-weight: 500;
  transition: color 0.3s var(--ease-precise);
  position: relative;
}
.nav-links a::after {
  content: ''; position: absolute; left: 0; bottom: -6px;
  width: 0; height: 1px; background: var(--cyan);
  transition: width 0.4s var(--ease-quiet);
}
.nav-links a:hover { color: var(--ink); }
.nav-links a:hover::after { width: 100%; }

/* ============ LAYOUT ============ */
.main-wrap {
  position: relative;
  z-index: 1;
  padding-top: 70px;
}
.content-wrap {
  max-width: 1240px;
  margin: 0 auto;
  padding: 4rem 2rem 8rem;
}

/* ============ SECTION ============ */
.section { padding: 5rem 0; border-bottom: 1px solid var(--line); }
.section-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem; letter-spacing: 0.22em;
  text-transform: uppercase; color: var(--cyan);
  margin-bottom: 1.2rem;
  display: inline-flex; align-items: center; gap: 0.6rem;
}
.section-label::before {
  content: ''; width: 18px; height: 1px; background: var(--cyan);
}
.section-h2 {
  font-family: 'Raleway', sans-serif;
  font-weight: 700;
  font-size: clamp(1.8rem, 3.5vw, 2.6rem);
  letter-spacing: -0.025em;
  line-height: 1.1;
  margin-bottom: 1.2rem;
}
.section-lead {
  font-size: 1.05rem; color: var(--ink-soft);
  max-width: 680px; line-height: 1.6;
  margin-bottom: 3rem;
}

/* ============ FOOTER ============ */
footer {
  border-top: 1px solid var(--line);
  background: var(--bg-soft);
  padding: 4rem 2rem 2rem;
  position: relative;
  z-index: 1;
}
.footer-grid {
  max-width: 1240px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 3rem;
  margin-bottom: 3rem;
}
.footer-brand p {
  font-size: 0.85rem; color: var(--ink-soft);
  margin-top: 1rem; max-width: 320px; line-height: 1.6;
}
.footer-col h5 {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem; letter-spacing: 0.2em;
  text-transform: uppercase; color: var(--ink-mute);
  margin-bottom: 1.2rem;
}
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 0.6rem; }
.footer-col a { font-size: 0.85rem; color: var(--ink-soft); transition: color 0.3s; }
.footer-col a:hover { color: var(--cyan); }
.footer-bottom {
  max-width: 1240px; margin: 0 auto;
  border-top: 1px solid var(--line);
  padding-top: 2rem;
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: 1rem;
}
.footer-bottom p {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem; color: var(--ink-mute);
  letter-spacing: 0.05em;
}

/* ============ ANIM HELPER ============ */
.reveal { opacity: 0; transform: translateY(30px); transition: opacity 1s var(--ease-emphasis), transform 1s var(--ease-emphasis); }
.reveal.in { opacity: 1; transform: none; }

/* ============ REDUCED MOTION ============ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
  #particle-canvas { display: none; }
}

/* ============ RESPONSIVE — SHARED ============ */
@media (max-width: 880px) {
  .nav-links { display: none; }
}
@media (max-width: 720px) {
  .content-wrap { padding: 2rem 1.5rem 5rem; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

/* ================================================================
   FRONT PAGE (index.html) — PAGE-SPECIFIC
   ================================================================ */

/* ============ HERO ============ */
.hero { padding: 4rem 0 5rem; border-bottom: 1px solid var(--line); }
.hero-meta {
  display: flex; align-items: center; gap: 1.2rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem; letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin-bottom: 2rem;
  flex-wrap: wrap;
}
.hero-meta span:first-child { color: var(--ink); }
.hero-meta::before {
  content: ''; width: 24px; height: 1px; background: var(--cyan);
}
#hero-title {
  font-family: 'Raleway', sans-serif;
  font-weight: 800;
  font-size: clamp(2.8rem, 7vw, 5.2rem);
  line-height: 0.98;
  letter-spacing: -0.045em;
  color: var(--ink);
  margin-bottom: 1.8rem;
}
#hero-title.is-decoding {
  text-shadow: 0 0 12px rgba(0,212,255,0.45), 0 0 30px rgba(0,212,255,0.2);
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
}
.hero-sub {
  font-size: 1.1rem;
  color: var(--ink-soft);
  max-width: 640px;
  line-height: 1.55;
}

/* ============ STICKY PAIR ============ */
.sticky-pair {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 4rem;
  align-items: start;
  margin-top: 4rem;
}
.sticky-pair .left {
  position: sticky; top: 90px;
  height: calc(100vh - 110px);
  display: flex; flex-direction: column; justify-content: center;
}
.sticky-pair .left h3 {
  font-family: 'Raleway', sans-serif;
  font-weight: 700;
  font-size: 2rem;
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin-bottom: 1.2rem;
}
.sticky-pair .left p {
  font-size: 0.95rem; color: var(--ink-soft);
  line-height: 1.6;
}

/* ============ RIGHT STACK / RFC CARDS ============ */
.right-stack { display: flex; flex-direction: column; gap: 2rem; }
.right-card {
  padding: 2rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg);
  transition: all 0.4s var(--ease-quiet);
}
.right-card:hover { border-color: var(--cyan); box-shadow: 0 0 0 1px var(--cyan); }
.right-card .num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem; letter-spacing: 0.15em;
  color: var(--cyan); margin-bottom: 1rem;
}
.right-card h4 {
  font-weight: 700; font-size: 1.2rem;
  margin-bottom: 0.8rem;
  letter-spacing: -0.01em;
}
.right-card p {
  font-size: 0.9rem; color: var(--ink-soft);
  line-height: 1.6;
}
.right-card .meta {
  display: flex; gap: 1rem; margin-top: 1.2rem;
  padding-top: 1.2rem; border-top: 1px solid var(--line);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem; color: var(--ink-mute);
  flex-wrap: wrap;
}
.right-card .meta span { display: flex; align-items: center; gap: 0.4rem; }
.right-card .meta span::before {
  content: ''; width: 5px; height: 5px; background: var(--cyan); border-radius: 50%;
}

/* ============ QUICK START LIST ============ */
.qs-list {
  display: flex; flex-direction: column;
  border-top: 1px solid var(--line);
  margin-top: 2rem;
}
.qs-row {
  display: grid;
  grid-template-columns: 60px 1fr 1.4fr 100px;
  align-items: center;
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--line);
  transition: background 0.4s var(--ease-quiet);
  gap: 1.5rem;
}
.qs-row:hover { background: var(--bg-soft); }
.qs-row .qs-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem; color: var(--ink-mute);
  letter-spacing: 0.05em;
}
.qs-row .qs-title { font-weight: 600; font-size: 0.95rem; }
.qs-row .qs-desc { font-size: 0.85rem; color: var(--ink-soft); }
.qs-row .qs-time {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem; color: var(--ink-mute);
  text-align: right;
}

/* ============ RESPONSIVE — FRONT PAGE ============ */
@media (max-width: 880px) {
  .sticky-pair { grid-template-columns: 1fr; gap: 2rem; }
  .sticky-pair .left { position: static; height: auto; }
  .qs-row {
    grid-template-columns: 1fr;
    gap: 0.4rem;
    padding: 1.2rem 0;
  }
  .qs-row .qs-time { text-align: left; }
}

/* ================================================================
   TEMPLATE ITEM (template_item.html) — PAGE-SPECIFIC
   ================================================================ */

/* ============ BACK LINK ============ */
.back-link {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  color: var(--ink-soft);
  padding: 0.5rem 0.95rem;
  border: 1px solid var(--line);
  border-radius: 5px;
  transition: all 0.4s var(--ease-quiet);
  margin-bottom: 2rem;
  background: var(--bg);
  text-transform: uppercase;
}
.back-link:hover {
  border-color: var(--ink);
  color: var(--ink);
}
.back-link svg {
  width: 12px; height: 12px;
  transition: transform 0.3s var(--ease-precise);
}
.back-link:hover svg { transform: translateX(-3px); }

/* ============ BREADCRUMB ============ */
.breadcrumb {
  display: flex; align-items: center; gap: 0.6rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--ink-mute);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}
.breadcrumb a { color: var(--ink-mute); transition: color 0.3s; }
.breadcrumb a:hover { color: var(--ink); }
.breadcrumb .sep { color: var(--line); }
.breadcrumb .current { color: var(--ink); }

/* ============ ARTICLE HERO ============ */
.article-hero {
  padding: 1rem 0 4rem;
  border-bottom: 1px solid var(--line);
}
.article-hero .section-label { margin-bottom: 1.5rem; }
#article-title {
  font-family: 'Raleway', sans-serif;
  font-weight: 800;
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--ink);
  margin-bottom: 1.2rem;
}
#article-title.is-decoding {
  text-shadow: 0 0 12px rgba(0,212,255,0.45), 0 0 30px rgba(0,212,255,0.2);
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
}
.article-sub {
  font-size: 1.05rem;
  color: var(--ink-soft);
  max-width: 620px;
  line-height: 1.55;
}
.article-meta {
  display: flex; gap: 1.5rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--ink-mute);
  letter-spacing: 0.05em;
  margin-top: 2.5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
  flex-wrap: wrap;
}
.article-meta span { display: flex; align-items: center; gap: 0.4rem; }
.article-meta span::before {
  content: ''; width: 5px; height: 5px; background: var(--cyan); border-radius: 50%;
}

/* ============ ARTICLE WRAP (TOC + BODY) ============ */
.article-wrap {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 4rem;
  align-items: start;
  margin-top: 4rem;
}

/* ============ TOC ============ */
.toc {
  position: sticky;
  top: 90px;
  height: calc(100vh - 110px);
  overflow-y: auto;
  padding: 0.5rem 0 2rem;
}
.toc::-webkit-scrollbar { width: 3px; }
.toc::-webkit-scrollbar-track { background: transparent; }
.toc::-webkit-scrollbar-thumb { background: var(--line); }
.toc-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin-bottom: 1rem;
  display: flex; align-items: center; gap: 0.5rem;
}
.toc-label::before {
  content: ''; width: 14px; height: 1px; background: var(--cyan);
}
.toc-list { display: flex; flex-direction: column; gap: 0.2rem; }
.toc-item {
  font-size: 0.8rem;
  color: var(--ink-mute);
  padding: 0.35rem 0.7rem;
  border-left: 2px solid transparent;
  transition: all 0.3s var(--ease-precise);
  line-height: 1.4;
}
.toc-item:hover { color: var(--ink); }
.toc-item.active {
  color: var(--ink);
  border-left-color: var(--cyan);
  background: linear-gradient(90deg, var(--cyan-soft) 0%, transparent 100%);
  font-weight: 600;
}
.toc-item.sub { padding-left: 1.4rem; font-size: 0.76rem; }

/* ============ ARTICLE BODY ============ */
.article-body { max-width: 720px; }
.article-body h2 {
  font-family: 'Raleway', sans-serif;
  font-weight: 700;
  font-size: 1.6rem;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin: 3rem 0 1rem;
  scroll-margin-top: 90px;
}
.article-body h2:first-child { margin-top: 0; }
.article-body h3 {
  font-family: 'Raleway', sans-serif;
  font-weight: 600;
  font-size: 1.1rem;
  letter-spacing: -0.01em;
  margin: 2rem 0 0.8rem;
  scroll-margin-top: 90px;
}
.article-body p {
  font-size: 0.95rem;
  color: var(--ink-soft);
  line-height: 1.7;
  margin-bottom: 1.2rem;
}
.article-body ul, .article-body ol {
  margin: 0 0 1.5rem 1.2rem;
}
.article-body li {
  font-size: 0.95rem;
  color: var(--ink-soft);
  margin-bottom: 0.5rem;
  line-height: 1.6;
}
.article-body strong { color: var(--ink); font-weight: 600; }
.article-body a.inline-link {
  color: var(--blue);
  border-bottom: 1px solid var(--line);
  transition: border-color 0.3s;
}
.article-body a.inline-link:hover { border-color: var(--blue); }

/* ============ INLINE CODE ============ */
code.inline {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.85em;
  padding: 0.15em 0.4em;
  background: var(--bg-soft);
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ink);
}

/* ============ CODE BLOCK ============ */
.code-block {
  background: var(--bg-ink);
  border-radius: 8px;
  overflow: hidden;
  margin: 1.5rem 0;
}
.code-block__header {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.6rem 1rem;
  border-bottom: 1px solid rgba(255,255,255,0.08);
  background: rgba(255,255,255,0.02);
}
.code-block__dots { display: flex; gap: 0.35rem; }
.code-block__dots span {
  width: 10px; height: 10px; border-radius: 50%;
  background: rgba(255,255,255,0.12);
}
.code-block__dots span:first-child { background: rgba(255,255,255,0.2); }
.code-block__file {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: rgba(255,255,255,0.5);
  margin-left: 0.5rem;
}
.code-block__lang {
  margin-left: auto;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.62rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--cyan);
}
.code-block pre {
  padding: 1.2rem 1.5rem;
  overflow-x: auto;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  line-height: 1.7;
  color: #e8e8ec;
}
.code-block pre::-webkit-scrollbar { height: 4px; }
.code-block pre::-webkit-scrollbar-track { background: transparent; }
.code-block pre::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.15); border-radius: 2px; }
.code-block .c-comment { color: #6b6b7a; }
.code-block .c-cmd { color: var(--cyan); }
.code-block .c-str { color: #ffb86c; }

/* ============ CALLOUT ============ */
.callout {
  display: flex; gap: 1rem;
  padding: 1.2rem 1.5rem;
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
  border-radius: 6px;
  margin: 1.5rem 0;
  background: var(--bg-soft);
}
.callout--warning { border-left-color: var(--orange); background: #fff8eb; }
.callout--danger { border-left-color: var(--red); background: #fff5f3; }
.callout__icon {
  flex-shrink: 0;
  width: 20px; height: 20px;
  color: var(--cyan);
  margin-top: 1px;
}
.callout--warning .callout__icon { color: var(--orange); }
.callout--danger .callout__icon { color: var(--red); }
.callout__content h5 {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 0.4rem;
  color: var(--ink);
}
.callout__content p {
  font-size: 0.9rem;
  color: var(--ink-soft);
  line-height: 1.6;
  margin: 0;
}
.callout__content p + p { margin-top: 0.6rem; }

/* ============ PAGER (PREV / NEXT) ============ */
.pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 5rem;
  padding-top: 3rem;
  border-top: 1px solid var(--line);
}
.pager-card {
  padding: 1.2rem 1.5rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  transition: all 0.4s var(--ease-quiet);
  background: var(--bg);
}
.pager-card:hover {
  border-color: var(--ink);
  transform: translateY(-2px);
}
.pager-card.next { text-align: right; }
.pager-card .label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin-bottom: 0.5rem;
  display: flex; align-items: center; gap: 0.4rem;
}
.pager-card.next .label { justify-content: flex-end; }
.pager-card .title {
  font-weight: 600;
  font-size: 1rem;
  color: var(--ink);
}
.pager-card .arrow {
  font-family: 'JetBrains Mono', monospace;
  color: var(--cyan);
}

/* ============ RESPONSIVE — TEMPLATE ITEM ============ */
@media (max-width: 1024px) {
  .article-wrap { grid-template-columns: 1fr; gap: 0; }
  .toc { display: none; }
}
@media (max-width: 720px) {
  .pager { grid-template-columns: 1fr; }
  .pager-card.next { text-align: left; }
  .pager-card.next .label { justify-content: flex-start; }
}