/* ============================================================
   Outdoor Bluebook — stylesheet
   单文件 CSS,深色为主,主题色沿用蓝皮书 #d8f238,
   辅以营火橙 #ff7a45 / 米黄 #efe9d6 / 远山蓝 #5fb3e8。
   ============================================================ */

:root{
  --bg:        #0a0d0e;
  --bg-soft:   #10141380;
  --bg-card:   #11171a;
  --ink:       #efe9d6;
  --ink-soft:  #b6b1a3;
  --ink-dim:   #6f6c63;
  --line:      #1c2120;
  --line-2:    #28302d;

  --accent:    #d8f238;       /* 电光柠檬绿,蓝皮书同款 */
  --accent-d:  #b0c71f;
  --orange:    #ff7a45;       /* 营火暖橙 */
  --orange-d:  #d65d2c;
  --sky:       #5fb3e8;
  --earth:     #a3907c;

  --maxw: 1180px;
  --gap:  clamp(16px, 2vw, 28px);

  --f-sans: 'Noto Serif SC', 'Source Han Serif SC', 'Songti SC', serif;
  --f-en:   'Instrument Serif', 'EB Garamond', Georgia, serif;
  --f-mono: 'JetBrains Mono', 'IBM Plex Mono', ui-monospace, Menlo, monospace;

  --shadow-1: 0 1px 0 #1c2120;
  --shadow-2: 0 24px 60px -28px #000;
  --ring: 0 0 0 1px var(--accent), 0 0 0 4px #d8f23822;

  --t-fast: 160ms cubic-bezier(.2,.7,.3,1);
  --t-med:  280ms cubic-bezier(.2,.7,.3,1);
}

[data-theme="light"]{
  --bg:     #f3efe2;
  --bg-card:#fbf7e8;
  --ink:    #1a1b16;
  --ink-soft:#4a4940;
  --ink-dim:#8a887e;
  --line:   #d8d3bf;
  --line-2: #b9b39c;
  --bg-soft:#fbf7e880;
}

/* ───────────── reset ───────────── */
*,*::before,*::after{ box-sizing: border-box; }
html{ scroll-behavior: smooth; }
body{
  margin: 0;
  color: var(--ink);
  font-family: var(--f-sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  background:
    linear-gradient(180deg, rgba(6,9,10,.55), rgba(6,9,10,.72)),
    url("../assets/img/bg-camp.png") center top / cover no-repeat,
    radial-gradient(1200px 600px at 20% -10%, #d8f23810, transparent 60%),
    radial-gradient(900px 500px at 95% 30%, #ff7a4510, transparent 60%)
    var(--bg);
  background-attachment: fixed;
}
img,svg{ display: block; max-width: 100%; }
a{ color: inherit; text-decoration: none; }
button{ font: inherit; cursor: pointer; }
code{ font-family: var(--f-mono); font-size: .92em; }
em{ font-style: italic; }

/* ───────────── utility ───────────── */
.mono{ font-family: var(--f-mono); letter-spacing: .02em; }
.dim{ opacity: .55; }

/* ───────────── topnav ───────────── */
.topnav{
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: blur(14px) saturate(1.1);
  background: linear-gradient(180deg, #0a0d0ecc 0%, #0a0d0e80 100%);
  border-bottom: 1px solid var(--line);
}
.topnav__inner{
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 14px 22px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 18px;
}
.brand{
  display: flex; align-items: center; gap: 10px;
  font-family: var(--f-mono);
  font-size: 12.5px;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.brand__glyph{
  color: var(--accent);
  font-size: 18px;
  text-shadow: 0 0 14px #d8f23899;
}
.brand__word em{ color: var(--accent); font-style: normal; }
.brand__cn{
  color: var(--ink-soft);
  text-transform: none;
  letter-spacing: 0;
  font-family: var(--f-sans);
  font-size: 13px;
  padding-left: 8px;
  border-left: 1px solid var(--line-2);
  margin-left: 4px;
}
.topnav__menu{
  display: flex; gap: 4px; justify-content: center;
}
.topnav__menu a{
  font-family: var(--f-mono);
  font-size: 12px;
  padding: 6px 10px;
  border-radius: 4px;
  color: var(--ink-soft);
  letter-spacing: .04em;
  transition: color var(--t-fast), background var(--t-fast);
}
.topnav__menu a:hover{ color: var(--ink); background: #d8f23814; }
.topnav__meta{
  justify-self: end;
  display: flex; align-items: center; gap: 8px;
  color: var(--ink-dim);
  font-family: var(--f-mono);
  font-size: 11.5px;
}
.dot{
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 3px #d8f23833, 0 0 10px #d8f238aa;
  animation: pulse 2.4s ease-in-out infinite;
}
@keyframes pulse{
  0%,100%{ opacity: 1; transform: scale(1); }
  50%{ opacity: .55; transform: scale(.85); }
}

/* ───────────── hero ───────────── */
.hero{
  position: relative;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(56px, 8vw, 110px) 22px clamp(48px, 6vw, 80px);
  overflow: hidden;
  background:
    radial-gradient(ellipse 1200px 400px at 50% 0%, rgba(216,242,56,.06), transparent 60%),
    radial-gradient(ellipse 800px 300px at 90% 30%, rgba(255,122,69,.05), transparent 70%),
    linear-gradient(180deg, var(--bg) 0%, rgba(6,9,10,.7) 80%, rgba(6,9,10,.9) 100%);
  border-radius: 6px;
}
.hero__deco{
  position: absolute; inset: 0;
  pointer-events: none;
  opacity: .4;
  background: radial-gradient(ellipse at 50% 0%, rgba(216,242,56,.04), transparent 70%);
}
.hero__deco-line{
  position: absolute;
  border-top: 1px dashed var(--line-2);
}
.hero__deco-line.l1{ left: -5%; right: 60%; top:  22%; }
.hero__deco-line.l2{ left: 40%; right: -10%; top: 60%; }
.hero__deco-line.l3{ left: 10%; right: 70%; top: 86%; }

.hero__topline{
  display: flex; flex-wrap: wrap; gap: 14px;
  color: var(--ink-dim);
  font-size: 11.5px;
  letter-spacing: .12em;
  text-transform: uppercase;
  margin-bottom: 32px;
}
.hero__topline i{ font-style: normal; opacity: .45; }

.hero__title{
  font-family: var(--f-en);
  font-weight: 400;
  letter-spacing: -0.015em;
  margin: 0 0 22px;
}
.hero__title-zh{
  display: block;
  font-family: var(--f-sans);
  font-weight: 900;
  font-size: clamp(48px, 9vw, 110px);
  line-height: 0.98;
  color: var(--ink);
  letter-spacing: -0.02em;
}
.hero__title-en{
  display: block;
  margin-top: 6px;
  font-size: clamp(22px, 3.4vw, 38px);
  color: var(--ink-soft);
}
.hero__title-en em{
  font-style: italic;
  color: var(--accent);
  font-weight: 400;
}

.hero__lede{
  max-width: 68ch;
  margin: 22px 0 36px;
  font-size: clamp(15.5px, 1.6vw, 18px);
  color: var(--ink-soft);
}
.hero__lede strong{
  color: var(--ink);
  font-weight: 500;
}
.hero__lede em{ color: var(--orange); font-style: normal; }

.hero__cta{
  display: flex; gap: 10px; flex-wrap: wrap;
  margin-bottom: 60px;
}

.btn{
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 18px;
  font-family: var(--f-mono);
  font-size: 12.5px;
  letter-spacing: .06em;
  border-radius: 2px;
  border: 1px solid transparent;
  background: transparent;
  color: var(--ink);
  transition: transform var(--t-fast), background var(--t-fast), color var(--t-fast), border-color var(--t-fast);
  white-space: nowrap;
}
.btn:hover{ transform: translateY(-1px); }
.btn--accent{
  background: var(--accent);
  color: #0a0d0e;
  font-weight: 700;
  box-shadow: 0 0 0 1px var(--accent), 6px 6px 0 #0a0d0e;
}
.btn--accent:hover{ background: var(--ink); color: var(--bg); box-shadow: 0 0 0 1px var(--ink), 8px 8px 0 var(--accent); }
.btn--accent .arrow{ transition: transform var(--t-fast); }
.btn--accent:hover .arrow{ transform: translateX(3px); }

.btn--ghost{
  border: 1px solid var(--line-2);
  color: var(--ink-soft);
}
.btn--ghost:hover{
  border-color: var(--accent);
  color: var(--accent);
}

.btn--mini{
  padding: 6px 10px;
  font-size: 11px;
  letter-spacing: .08em;
}

.hero__stats{
  list-style: none;
  margin: 0; padding: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  max-width: 720px;
}
.hero__stats li{
  background: var(--bg-soft);
  backdrop-filter: blur(6px);
  padding: 14px 16px;
  display: flex; flex-direction: column; gap: 4px;
}
.hero__stats b{
  font-family: var(--f-en);
  font-size: 28px;
  color: var(--accent);
  font-weight: 400;
}
.hero__stats span{
  font-family: var(--f-mono);
  font-size: 11px;
  color: var(--ink-dim);
  letter-spacing: .12em;
  text-transform: uppercase;
}

/* ───────────── section heads ───────────── */
.section-head{
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 32px 22px 24px;
  display: grid;
  gap: 8px;
}
.section-head__tag{
  color: var(--accent);
  font-size: 12px;
  letter-spacing: .14em;
  text-transform: uppercase;
}
.section-head__title{
  font-family: var(--f-sans);
  font-weight: 900;
  font-size: clamp(28px, 4.2vw, 44px);
  letter-spacing: -0.015em;
  margin: 0;
}
.section-head__desc{
  color: var(--ink-soft);
  max-width: 68ch;
  margin: 4px 0 0;
}
.section-head__desc em{ color: var(--orange); font-style: normal; }

/* ───────────── outline ───────────── */
.outline{
  max-width: var(--maxw);
  margin: 0 auto;
  padding-bottom: 32px;
}
.outline__grid{
  padding: 0 22px;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1px;
  background: var(--line);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.ol-item{
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
  padding: 14px 16px;
  background: var(--bg);
  transition: background var(--t-fast), color var(--t-fast);
}
.ol-item:hover{ background: #d8f23811; }
.ol-item__no{
  color: var(--orange);
  font-size: 12.5px;
  width: 32px;
}
.ol-item__title{
  font-size: 14.5px;
  color: var(--ink);
}
.ol-item__arr{
  color: var(--ink-dim);
  font-family: var(--f-mono);
  font-size: 12px;
  transition: transform var(--t-fast), color var(--t-fast);
}
.ol-item:hover .ol-item__arr{
  color: var(--accent);
  transform: translateX(4px);
}

/* ───────────── part / chapters ───────────── */
.part{
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(40px, 6vw, 80px) 22px 24px;
  border-top: 1px solid var(--line);
  position: relative;
}
.part:first-of-type{ border-top: 0; }
.part__head{
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: clamp(20px, 4vw, 60px);
  margin-bottom: 36px;
}
.part__head-no{
  font-family: var(--f-mono);
  font-size: 11.5px;
  letter-spacing: .14em;
  color: var(--accent);
  padding-top: 14px;
  border-top: 1px solid var(--accent);
  display: inline-block;
}
.part__head-eyebrow{
  font-size: 12px;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ink-dim);
  margin-bottom: 12px;
}
.part__head-title{
  font-family: var(--f-sans);
  font-weight: 900;
  font-size: clamp(32px, 5vw, 56px);
  letter-spacing: -0.02em;
  line-height: 1.05;
  margin: 0 0 12px;
}
.part__head-desc{
  color: var(--ink-soft);
  max-width: 64ch;
  margin: 0;
}
.part__head-desc strong{ color: var(--orange); font-weight: 500; }

.part__grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  gap: 22px;
}

/* ───────────── cards ───────────── */
.card{
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 26px 26px 22px;
  transition: transform var(--t-med), border-color var(--t-med), background var(--t-med);
  overflow: hidden;
  isolation: isolate;
}
.card::before{
  content: ""; position: absolute;
  inset: 0 auto 0 0; width: 3px;
  background: var(--accent);
  transform: scaleY(0);
  transform-origin: top;
  transition: transform var(--t-med);
  z-index: 1;
}
.card:hover{
  border-color: var(--line-2);
  transform: translateY(-3px);
}
.card:hover::before{ transform: scaleY(1); }

.card--topic{ display: grid; gap: 8px; }
.card__head{
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 8px;
}
.card__no{
  color: var(--accent);
  font-size: 11.5px;
  letter-spacing: .14em;
}
.card__tags{
  display: flex; flex-wrap: wrap; gap: 6px; justify-content: flex-end;
}
.tag{
  font-family: var(--f-mono);
  font-size: 10.5px;
  letter-spacing: .04em;
  padding: 3px 7px;
  border-radius: 2px;
  border: 1px solid var(--line-2);
  color: var(--ink-soft);
  background: #d8f2380a;
}
.tag--orange{ color: var(--orange); border-color: #ff7a4555; background: #ff7a4510; }
.tag--sky{ color: var(--sky); border-color: #5fb3e855; background: #5fb3e810; }
.tag--earth{ color: var(--earth); border-color: #a3907c55; background: #a3907c10; }

.card__title{
  font-family: var(--f-sans);
  font-weight: 900;
  font-size: 24px;
  letter-spacing: -0.01em;
  margin: 4px 0 2px;
  line-height: 1.2;
}
.card__sub{
  font-family: var(--f-en);
  font-style: italic;
  font-size: 17px;
  color: var(--accent);
  margin: 0;
}
.card__lede{
  color: var(--ink-soft);
  margin: 4px 0 6px;
  font-size: 14.5px;
}
.card__pts{
  list-style: none; padding: 0; margin: 6px 0 14px;
  display: block;
  font-size: 13.5px;
  color: var(--ink-soft);
  border-top: 1px dashed var(--line-2);
  padding-top: 14px;
}
.card__pts li{
  position: relative;
  padding-left: 20px;
  margin: 3px 0;
}
.card__pts li::before{
  content: "▸";
  position: absolute;
  left: 0;
  top: 0;
  color: var(--orange);
  font-family: var(--f-mono);
  font-size: 12px;
}
.card__foot{
  display: flex; gap: 8px; justify-content: flex-end;
  margin-top: auto;
}

/* essay cards on the colophon */
.card--essay{ padding: 30px 28px; }
.card--essay h3{
  font-family: var(--f-en);
  font-weight: 400;
  font-style: italic;
  font-size: 26px;
  color: var(--accent);
  margin: 0 0 10px;
}
.card--essay p{
  color: var(--ink-soft);
  margin: 0;
}
.card--essay strong{ color: var(--ink); font-weight: 500; }
.card--essay em{ color: var(--orange); font-style: normal; }

/* ───────────── colophon ───────────── */
.colophon{
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 30px 22px 60px;
  border-top: 1px solid var(--line);
}
.colophon__grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 22px;
}

/* ───────────── footer ───────────── */
.footer{
  border-top: 1px solid var(--line);
  background: #070a0b80;
  padding: 24px 22px;
}
.footer__inner{
  max-width: var(--maxw);
  margin: 0 auto;
  display: flex; justify-content: space-between; align-items: center;
  gap: 16px;
  font-family: var(--f-mono);
  font-size: 11.5px;
  color: var(--ink-dim);
  flex-wrap: wrap;
}
.footer__inner i{ font-style: normal; opacity: .5; padding: 0 6px; }
.footer__left{ display: flex; gap: 10px; flex-wrap: wrap; }
.footer__right{ display: flex; gap: 4px; }

/* ───────────── responsive ───────────── */
@media (max-width: 880px){
  .topnav__inner{ grid-template-columns: 1fr auto; }
  .topnav__menu{ display: none; }
  .part__head{ grid-template-columns: 1fr; gap: 14px; }
  .part__head-no{ padding-top: 8px; }
  .hero__stats{ grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 520px){
  .outline__grid{ grid-template-columns: 1fr 1fr; }
  .part__grid{ grid-template-columns: 1fr; }
  .topnav__inner{ padding: 12px 14px; }
  .brand__cn{ display: none; }
  .hero, .outline, .part, .colophon{ padding-left: 16px; padding-right: 16px; }
  .footer__inner{ flex-direction: column; align-items: flex-start; }
}

/* ───────────── scroll reveal ───────────── */
.reveal{
  opacity: 0; transform: translateY(14px);
  transition: opacity .6s var(--t-med), transform .6s var(--t-med);
}
.reveal.in{
  opacity: 1; transform: none;
}

/* ───────────── focus ───────────── */
:focus-visible{ outline: 2px solid var(--accent); outline-offset: 2px; }

/* ───────────── selection ───────────── */
::selection{ background: var(--accent); color: var(--bg); }