/* Unboxd — "system console" theme.
   Near-black canvas, electric cyan + violet accents, faint grid overlay,
   mono system tags, glowing spec tiles. Dark UI, sharp, technical. */

:root {
  --bg: #0b0e14;
  --panel: #121826;
  --panel-2: #0e1320;
  --ink: #e7ecf3;
  --muted: #94a1b5;
  --faint: #5c6675;
  --line: #222c3e;
  --line-2: #2f3b52;
  --cyan: #2fe6d0;
  --cyan-deep: #12a99a;
  --violet: #8b7bff;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--bg); color: var(--ink); font-family: var(--sans); font-size: 17px; line-height: 1.7; -webkit-font-smoothing: antialiased; position: relative; }
.gridfx { position: fixed; inset: 0; z-index: 0; pointer-events: none;
  background-image: linear-gradient(rgba(47,230,208,0.045) 1px, transparent 1px), linear-gradient(90deg, rgba(47,230,208,0.045) 1px, transparent 1px);
  background-size: 40px 40px; mask-image: radial-gradient(ellipse at 50% 0%, #000 0, transparent 78%); }
.site-head, main, .site-foot { position: relative; z-index: 1; }
.wrap { max-width: 1020px; margin: 0 auto; padding: 0 24px; }
a { color: var(--cyan); text-decoration: none; }
a:hover { color: var(--violet); }

/* ---------- header ---------- */
.site-head { border-bottom: 1px solid var(--line); background: rgba(11,14,20,0.86); backdrop-filter: blur(6px); }
.head-row { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 14px; padding: 16px 24px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-family: var(--mono); font-weight: 700; letter-spacing: 0.24em; font-size: 17px; color: var(--ink); }
.brand:hover { color: var(--cyan); }
.brand-mark { position: relative; width: 15px; height: 15px; border: 2px solid var(--cyan); border-radius: 3px; transform: rotate(45deg); box-shadow: 0 0 10px rgba(47,230,208,0.55); }
.brand-mark i { position: absolute; inset: 3px; background: var(--cyan); border-radius: 1px; }
.nav { display: flex; flex-wrap: wrap; gap: 16px; font-family: var(--mono); font-size: 12px; letter-spacing: 0.08em; text-transform: uppercase; }
.nav a { color: var(--muted); }
.nav a:hover { color: var(--cyan); }

/* ---------- hero ---------- */
.hero { padding: 54px 0 20px; }
.eyebrow { font-family: var(--mono); font-size: 12px; letter-spacing: 0.2em; text-transform: uppercase; color: var(--cyan); margin: 0 0 14px; }
.hero h1 { font-size: 40px; line-height: 1.08; margin: 0 0 16px; letter-spacing: -0.02em;
  background: linear-gradient(92deg, var(--ink) 0 55%, var(--cyan) 100%); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero-sub { color: var(--muted); max-width: 48em; font-size: 18px; margin: 0; }

/* ---------- chapters ---------- */
.chapter { padding: 34px 0 6px; }
.chapter-head { display: flex; align-items: baseline; gap: 12px; border-bottom: 1px solid var(--line-2); padding-bottom: 9px; }
.chapter-tag { font-family: var(--mono); font-size: 13px; letter-spacing: 0.06em; color: var(--cyan); text-transform: uppercase; }
.chapter-tag.big { font-size: 14px; }
.chapter-head .chapter-tag { font-size: 22px; font-weight: 700; text-transform: none; letter-spacing: -0.01em; color: var(--ink); }
.chapter-tag.big.front { font-size: 20px; }
.chapter-count { margin-left: auto; font-family: var(--mono); font-size: 12px; color: var(--faint); }
.chapter-blurb { color: var(--muted); margin: 10px 0 18px; max-width: 48em; }
.chapter-blurb.big { font-size: 18px; }
.chapter-intro { padding: 34px 0 8px; }
.chapter-intro h1 { font-size: 33px; margin: 12px 0 8px; letter-spacing: -0.02em; }
.crumbs { font-family: var(--mono); font-size: 13px; color: var(--faint); padding: 32px 0 4px; }
.crumbs a { color: var(--cyan); }
.crumbs span { margin: 0 8px; color: var(--line-2); }

/* ---------- tiles ---------- */
.tiles { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 12px; padding-bottom: 10px; }
.tile { display: flex; flex-direction: column; gap: 6px; background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 15px 16px; color: var(--ink); transition: border-color .12s ease, box-shadow .12s ease, transform .12s ease; }
.tile:hover { border-color: var(--cyan-deep); box-shadow: 0 0 0 1px rgba(47,230,208,0.25), 0 12px 30px -18px rgba(47,230,208,0.6); transform: translateY(-2px); }
.tile-no { font-family: var(--mono); font-size: 12px; color: var(--cyan); letter-spacing: 0.1em; }
.tile-name { font-weight: 600; font-size: 16px; line-height: 1.3; }
.tile-meta { font-family: var(--mono); font-size: 11px; color: var(--muted); letter-spacing: 0.02em; }
.tile-meta .sep { color: var(--violet); }
.empty { color: var(--faint); font-style: italic; margin: 4px 0 18px; }

/* ---------- article ---------- */
.feat-head { padding: 8px 0 22px; border-bottom: 1px solid var(--line-2); }
.feat-tag { display: inline-block; font-family: var(--mono); font-size: 12px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--bg); background: var(--cyan); padding: 3px 10px; border-radius: 4px; margin-bottom: 12px; font-weight: 700; }
.feat-head h1 { font-size: 34px; line-height: 1.12; margin: 0; letter-spacing: -0.02em; }
.feat-head .zh { color: var(--faint); font-size: 15px; margin: 8px 0 0; }

.specs { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: 10px; overflow: hidden; margin: 24px 0 36px; }
.spec { background: var(--panel-2); padding: 13px 15px; }
.spec-l { display: block; font-family: var(--mono); font-size: 10px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--faint); margin-bottom: 4px; }
.spec-v { display: block; font-weight: 600; font-size: 15px; color: var(--cyan); }

.module { margin: 0 0 30px; padding-left: 18px; border-left: 2px solid var(--line-2); }
.module h2 { display: flex; align-items: baseline; font-size: 21px; margin: 0 0 10px; letter-spacing: -0.01em; }
.module-no { font-family: var(--mono); font-size: 13px; color: var(--violet); margin-right: 12px; }
.module-body p { margin: 0 0 14px; color: #d3dbe6; }
.module-body p:last-child { margin-bottom: 0; }

.related-nav { margin-top: 42px; padding-top: 22px; border-top: 1px solid var(--line-2); }
.related-nav h2 { font-family: var(--mono); font-size: 15px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); margin: 0 0 14px; }
.chips { display: flex; flex-wrap: wrap; gap: 9px; }
.chip { display: inline-block; font-family: var(--mono); font-size: 13px; padding: 7px 13px; border: 1px solid var(--line-2); border-radius: 999px; color: var(--cyan); }
.chip:hover { border-color: var(--cyan); background: rgba(47,230,208,0.08); }
.chip-dim { border-style: dashed; color: var(--faint); }
.chip-dim i { font-style: normal; font-size: 10px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--violet); margin-left: 6px; }

/* ---------- legal / 404 ---------- */
.legal { padding: 44px 0 60px; max-width: 800px; }
.legal h1 { font-size: 32px; margin: 8px 0 10px; letter-spacing: -0.02em; }
.legal h2 { font-size: 20px; margin: 26px 0 8px; color: var(--ink); }
.legal p, .legal li { color: var(--muted); }
.legal ul { padding-left: 22px; }
.notfound { padding: 66px 0 92px; }
.notfound h1 { font-size: 36px; margin: 4px 0 8px; letter-spacing: -0.02em; }
.back { margin: 26px 0 0; font-family: var(--mono); font-size: 14px; }

/* ---------- footer ---------- */
.site-foot { border-top: 1px solid var(--line); background: var(--bg); padding: 28px 0 38px; font-size: 14px; color: var(--muted); }
.site-foot p { margin: 0 0 10px; max-width: 58em; }
.site-foot a { color: var(--cyan); }
.site-foot a:hover { color: var(--violet); }
.foot-links { font-family: var(--mono); display: flex; flex-wrap: wrap; gap: 10px; }
.foot-links span { opacity: 0.5; }
.foot-fine { font-family: var(--mono); font-size: 12px; opacity: 0.6; }

@media (max-width: 640px) {
  .hero h1 { font-size: 31px; }
  .feat-head h1 { font-size: 27px; }
  .head-row { flex-direction: column; align-items: flex-start; }
  .chapter-count { margin-left: 0; }
}