@import url('https://fonts.googleapis.com/css2?family=Shippori+Mincho:wght@500;700;800&family=Zen+Kaku+Gothic+New:wght@400;500;700;900&family=JetBrains+Mono:wght@400;500;700&display=swap');

:root{
  --paper:#efece2;
  --paper-deep:#e6e2d4;
  --ink:#232a26;
  --ink-soft:#5b6259;
  --line:#c9c2ab;
  --teal:#2f6f62;
  --teal-deep:#1f4b42;
  --amber:#c1812f;
  --amber-soft:#f1ddb8;
  --red-flag:#a4432f;
  --card:#f7f5ec;
  --shadow: 0 1px 0 rgba(35,42,38,0.06);
}

*{box-sizing:border-box;}
html{scroll-behavior:smooth;}

body{
  margin:0;
  background:
    linear-gradient(var(--paper) 0%, var(--paper) 100%);
  color:var(--ink);
  font-family:'Zen Kaku Gothic New', sans-serif;
  font-size:16px;
  line-height:1.85;
  -webkit-font-smoothing:antialiased;
}

/* faint graph-paper texture on the page background */
body::before{
  content:"";
  position:fixed;
  inset:0;
  background-image:
    linear-gradient(rgba(35,42,38,0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(35,42,38,0.035) 1px, transparent 1px);
  background-size: 28px 28px;
  pointer-events:none;
  z-index:0;
}

.app{
  position:relative;
  z-index:1;
  display:grid;
  grid-template-columns: 232px 1fr;
  min-height:100vh;
}

/* ---------- Binder rail (signature nav) ---------- */
.rail{
  position:sticky;
  top:0;
  height:100vh;
  background:var(--teal-deep);
  color:#eee7d6;
  padding:28px 0 20px;
  display:flex;
  flex-direction:column;
  border-right:3px solid var(--ink);
}

.rail-holes{
  position:absolute;
  left:10px;
  top:0;
  bottom:0;
  width:14px;
}
.rail-brand{
  padding:0 22px 22px;
  border-bottom:1px dashed rgba(238,231,214,0.35);
  margin:0 14px 18px;
}
.rail-brand .kicker{
  font-family:'JetBrains Mono', monospace;
  font-size:11px;
  letter-spacing:.14em;
  color:var(--amber-soft);
  display:block;
  margin-bottom:8px;
}
.rail-brand h1{
  font-family:'Shippori Mincho', serif;
  font-size:21px;
  line-height:1.5;
  margin:0;
  font-weight:700;
}

.rail-nav{
  list-style:none;
  margin:0;
  padding:0 12px;
  flex:1;
}
.rail-nav li{margin-bottom:6px;}
.rail-nav a{
  display:flex;
  align-items:baseline;
  gap:10px;
  text-decoration:none;
  color:#e6e0cc;
  padding:11px 12px;
  border-radius:3px;
  font-size:14px;
  border-left:3px solid transparent;
  transition:background .15s ease, border-color .15s ease, transform .15s ease;
}
.rail-nav a .num{
  font-family:'JetBrains Mono', monospace;
  font-size:12px;
  color:var(--amber-soft);
  opacity:.85;
}
.rail-nav a:hover{
  background:rgba(238,231,214,0.08);
  transform:translateX(2px);
}
.rail-nav a.active{
  background:var(--paper);
  color:var(--ink);
  border-left-color:var(--amber);
  font-weight:700;
}
.rail-nav a.active .num{color:var(--teal-deep);}

.rail-foot{
  padding:16px 22px 0;
  font-size:11.5px;
  color:rgba(230,224,204,0.6);
  border-top:1px dashed rgba(238,231,214,0.35);
  margin:18px 14px 0;
}

/* ---------- Main content ---------- */
main{
  padding: 56px clamp(24px, 6vw, 96px) 120px;
  max-width: 900px;
}

.eyebrow{
  font-family:'JetBrains Mono', monospace;
  font-size:12.5px;
  letter-spacing:.12em;
  color:var(--teal-deep);
  text-transform:uppercase;
  display:flex;
  align-items:center;
  gap:10px;
  margin-bottom:14px;
}
.eyebrow::before{
  content:"";
  width:28px;height:2px;background:var(--amber);display:inline-block;
}

h1.page-title{
  font-family:'Shippori Mincho', serif;
  font-size:clamp(30px, 4vw, 44px);
  line-height:1.4;
  margin:0 0 6px;
  font-weight:800;
}
.lede{
  font-size:17.5px;
  color:var(--ink-soft);
  max-width:62ch;
  margin:14px 0 44px;
}

h2{
  font-family:'Shippori Mincho', serif;
  font-size:26px;
  margin:56px 0 18px;
  padding-bottom:12px;
  border-bottom:2px solid var(--ink);
  display:flex;
  align-items:baseline;
  gap:12px;
}
h2 .chap{
  font-family:'JetBrains Mono', monospace;
  font-size:14px;
  color:var(--teal);
  border:1px solid var(--teal);
  padding:2px 8px;
  border-radius:3px;
}
h3{
  font-family:'Zen Kaku Gothic New', sans-serif;
  font-size:18.5px;
  font-weight:900;
  margin:30px 0 12px;
  color:var(--teal-deep);
}
p{margin:0 0 16px;}
ul,ol{padding-left:1.3em; margin:0 0 18px;}
li{margin-bottom:8px;}
strong{color:var(--ink); font-weight:900;}

a.inline{color:var(--teal-deep); font-weight:700; text-decoration-thickness:1.5px;}

/* ---------- Cards / index-card component ---------- */
.card{
  background:var(--card);
  border:1px solid var(--line);
  border-radius:6px;
  padding:22px 24px;
  box-shadow:var(--shadow);
  margin:20px 0;
}
.card-title{
  font-weight:900;
  font-size:15px;
  margin-bottom:8px;
  display:flex;
  gap:8px;
  align-items:center;
}

.grid-2{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:18px;
  margin:22px 0 30px;
}
@media (max-width:760px){ .grid-2{grid-template-columns:1fr;} }

/* weak / strong prompt comparison */
.compare{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:16px;
  margin:20px 0 32px;
}
@media (max-width:760px){ .compare{grid-template-columns:1fr;} }
.compare .box{
  border-radius:6px;
  padding:18px 20px;
  font-size:14.5px;
  line-height:1.75;
}
.compare .weak{
  background:#f4e7e0;
  border:1px solid #d8b6a4;
}
.compare .strong{
  background:#e7efe6;
  border:1px solid #a9c7ad;
}
.compare .tag{
  font-family:'JetBrains Mono', monospace;
  font-size:11px;
  letter-spacing:.08em;
  text-transform:uppercase;
  font-weight:700;
  display:inline-block;
  margin-bottom:10px;
  padding:3px 9px;
  border-radius:3px;
}
.compare .weak .tag{background:var(--red-flag); color:#fff;}
.compare .strong .tag{background:var(--teal-deep); color:#fff;}

/* prompt code block */
.prompt-block{
  background:#1d2420;
  color:#eae4d1;
  border-radius:8px;
  padding:20px 22px;
  font-family:'JetBrains Mono', monospace;
  font-size:13.5px;
  line-height:1.85;
  white-space:pre-wrap;
  word-break:break-word;
  margin:16px 0 28px;
  border:1px solid #384038;
  position:relative;
}
.prompt-block .label{
  position:absolute;
  top:-11px;
  left:16px;
  background:var(--amber);
  color:#241a08;
  font-size:11px;
  font-weight:700;
  letter-spacing:.06em;
  padding:2px 10px;
  border-radius:3px;
  font-family:'Zen Kaku Gothic New', sans-serif;
}

.callout{
  border-left:4px solid var(--amber);
  background:var(--amber-soft);
  padding:16px 20px;
  border-radius:0 6px 6px 0;
  margin:22px 0;
  font-size:14.5px;
}
.callout.danger{border-left-color:var(--red-flag); background:#f4e2db;}
.callout .callout-title{font-weight:900; margin-bottom:6px; display:block;}

table{
  width:100%;
  border-collapse:collapse;
  margin:20px 0 32px;
  font-size:14.5px;
  background:var(--card);
  border-radius:6px;
  overflow:hidden;
  border:1px solid var(--line);
}
th,td{
  text-align:left;
  padding:12px 14px;
  border-bottom:1px solid var(--line);
  vertical-align:top;
}
th{
  background:var(--teal-deep);
  color:#f2eedd;
  font-weight:700;
  font-size:13px;
}
tr:last-child td{border-bottom:none;}

.checklist{list-style:none; padding:0;}
.checklist li{
  display:flex;
  gap:12px;
  align-items:flex-start;
  padding:10px 0;
  border-bottom:1px dashed var(--line);
}
.checklist li:last-child{border-bottom:none;}
.checklist .box-icon{
  flex-shrink:0;
  width:18px;height:18px;
  border:2px solid var(--teal-deep);
  border-radius:3px;
  margin-top:3px;
}

/* toc index on home page */
.toc-list{list-style:none; padding:0; margin:0;}
.toc-list li{margin-bottom:14px;}
.toc-list a{
  display:flex;
  align-items:center;
  gap:18px;
  text-decoration:none;
  color:var(--ink);
  background:var(--card);
  border:1px solid var(--line);
  border-radius:8px;
  padding:18px 22px;
  transition:transform .15s ease, box-shadow .15s ease;
}
.toc-list a:hover{
  transform:translateX(4px);
  box-shadow:2px 3px 0 var(--ink);
}
.toc-list .toc-num{
  font-family:'JetBrains Mono', monospace;
  font-size:22px;
  font-weight:700;
  color:var(--teal);
  width:38px;
}
.toc-list .toc-body h3{margin:0 0 4px; font-size:16.5px;}
.toc-list .toc-body p{margin:0; font-size:13.5px; color:var(--ink-soft);}

.pagenav{
  display:flex;
  justify-content:space-between;
  gap:16px;
  margin-top:70px;
  padding-top:24px;
  border-top:2px solid var(--ink);
}
.pagenav a{
  text-decoration:none;
  color:var(--ink);
  font-weight:700;
  font-size:14px;
  display:flex;
  flex-direction:column;
  gap:4px;
  max-width:45%;
}
.pagenav a span.dir{font-size:11px; color:var(--ink-soft); font-weight:400; font-family:'JetBrains Mono', monospace;}
.pagenav a.next{text-align:right; align-items:flex-end; margin-left:auto;}

/* mobile: collapse rail */
@media (max-width: 860px){
  .app{grid-template-columns:1fr;}
  .rail{
    position:relative;
    height:auto;
    padding:20px 0;
  }
  .rail-nav{display:flex; flex-wrap:wrap; gap:6px; padding:0 14px;}
  .rail-nav li{margin:0;}
  main{padding:36px 20px 90px;}
}

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