:root{
  --navy:#1b3a3a; --navy2:#2d5147; --teal:#3c7a6a; --teal-light:#5fa790;
  --gold:#c08a2e; --bg:#f4ede1; --card:#fbf6ec; --ink:#2b2620; --muted:#7a7265;
  --border:#e6dcc8; --green:#3c7a4f; --red:#b3492f; --shadow:0 6px 24px rgba(60,50,30,.09);
}
@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:ital,wght@0,600;0,700;0,800;1,600;1,700&family=Source+Serif+4:wght@400;500;600;700&family=JetBrains+Mono:wght@500;600&display=swap');
*{box-sizing:border-box}
body{margin:0;font-family:'Source Serif 4',Georgia,'Times New Roman',serif;background:var(--bg);color:var(--ink);line-height:1.65;font-size:.96rem;letter-spacing:.1px}
h1,h2,h3,h4{font-family:'Playfair Display',Georgia,serif;letter-spacing:.2px}
.mono,.badge,.chcard .num,nav.crumb,.tag{font-family:'JetBrains Mono',Consolas,monospace;letter-spacing:.06em}
a{color:var(--teal);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:1100px;margin:0 auto;padding:0 20px}
header.top{background:var(--bg);color:var(--ink);padding:38px 0 26px;border-bottom:1px solid var(--border)}
header.top .tag{display:inline-block;color:var(--gold);font-size:.72rem;font-weight:600;letter-spacing:.18em;text-transform:uppercase;margin-bottom:10px}
header.top h1{margin:0;font-size:2.6rem;font-weight:800;color:var(--navy);line-height:1.08}
header.top h1 em{display:block;color:var(--teal);font-style:italic;font-weight:700}
header.top p{margin:14px 0 0;color:var(--muted);font-size:1rem;max-width:640px}
.backlink{display:inline-block;margin-bottom:14px;font-weight:600;color:var(--teal);font-family:'JetBrains Mono',monospace;font-size:.8rem;letter-spacing:.06em}
.backlink:hover{color:var(--navy)}
nav.crumb{background:transparent;padding:10px 0;font-size:.78rem;color:var(--muted)}
nav.crumb a{color:var(--teal);font-weight:600}
section{padding:30px 0}
h2{display:block;color:var(--navy);border-bottom:2px solid var(--border);padding-bottom:10px;margin:0 0 18px;font-weight:800;font-size:1.7rem}
h2 em{color:var(--teal);font-style:italic}
h3{color:var(--navy2);font-weight:700;font-size:1.2rem}
.card{background:var(--card);border:1px solid var(--border);border-radius:6px;border-top:3px solid var(--teal);padding:22px;box-shadow:var(--shadow);margin-bottom:20px}
.grid{display:grid;gap:18px}
.grid-2{grid-template-columns:repeat(auto-fit,minmax(320px,1fr))}
.grid-3{grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}
.grid-4{grid-template-columns:repeat(auto-fit,minmax(180px,1fr))}
.badge{display:inline-block;background:var(--navy);color:#f4ede1;border-radius:3px;padding:4px 12px;font-size:.7rem;font-weight:600;margin:2px;letter-spacing:.08em;text-transform:uppercase}
.badge.gold{background:var(--gold);color:#fff}
.badge.navy{background:var(--navy2);color:#fff}
.badge.green{background:var(--green);color:#fff}
.badge.red{background:var(--red);color:#fff}
table{border-collapse:collapse;width:100%;margin:14px 0;font-size:.85rem}
th,td{border:1px solid var(--border);padding:9px 12px;text-align:left}
th{background:var(--navy);color:#f4ede1;font-family:'JetBrains Mono',monospace;font-size:.72rem;letter-spacing:.07em;text-transform:uppercase;font-weight:600}
tr:nth-child(even){background:#efe6d6}
.formula{background:var(--navy);color:#cfe9da;padding:14px 18px;border-radius:6px;font-family:'JetBrains Mono',Consolas,monospace;font-size:.86rem;margin:12px 0;overflow-x:auto;border-left:4px solid var(--teal-light)}
.example{background:#f3ead6;border-left:4px solid var(--gold);padding:14px 18px;border-radius:4px;margin:14px 0}
.example h4{margin:0 0 6px;color:var(--gold);font-family:'JetBrains Mono',monospace;font-size:.78rem;letter-spacing:.08em;text-transform:uppercase}
.tip{background:#e9efe5;border-left:4px solid var(--green);padding:14px 18px;border-radius:4px;margin:14px 0}
.note{background:#e8eef0;border-left:4px solid var(--teal);padding:14px 18px;border-radius:4px;margin:14px 0}

/* mindmap / flow */
.mindmap{display:flex;flex-wrap:wrap;gap:14px;justify-content:center;align-items:center;padding:16px}
.mnode{background:var(--navy);color:#f4ede1;border:1px solid var(--navy2);border-radius:6px;padding:13px 20px;font-weight:600;font-family:'JetBrains Mono',monospace;font-size:.78rem;letter-spacing:.05em;text-transform:uppercase;text-align:center;box-shadow:var(--shadow);min-width:140px}
.mnode.center{background:var(--gold);color:#fff;border-color:var(--gold);font-size:.92rem}
.arrow{color:var(--muted);font-size:1.4rem}

/* progress bars (weightage chart) */
.barrow{display:flex;align-items:center;gap:10px;margin:8px 0}
.barlabel{width:230px;font-weight:600;font-size:.85rem;font-family:'Source Serif 4',serif}
.bartrack{flex:1;background:var(--border);border-radius:3px;height:20px;overflow:hidden}
.barfill{height:100%;background:var(--teal);border-radius:3px;display:flex;align-items:center;justify-content:flex-end;color:#fff;font-size:.72rem;font-weight:700;padding-right:8px;white-space:nowrap;font-family:'JetBrains Mono',monospace}
.barval{width:50px;text-align:right;font-weight:700;color:var(--navy);font-family:'JetBrains Mono',monospace;font-size:.85rem}

/* chapter cards on index */
.chcard{display:block;background:var(--card);border:1px solid var(--border);border-top:3px solid var(--teal);border-radius:6px;padding:18px 20px;box-shadow:var(--shadow);transition:.15s;text-decoration:none;color:inherit}
.chcard:hover{transform:translateY(-2px);box-shadow:0 10px 28px rgba(60,50,30,.16);text-decoration:none;border-top-color:var(--gold)}
.chcard .num{display:inline-block;background:var(--navy);color:#f4ede1;border-radius:3px;width:30px;height:30px;text-align:center;line-height:30px;font-weight:600;margin-right:10px;font-size:.8rem}
.chcard h3{margin:8px 0 4px;color:var(--navy)}
.chcard p{margin:0;color:var(--muted);font-size:.86rem;font-family:'Source Serif 4',serif}

/* timeline / study plan */
.timeline{position:relative;padding-left:34px;border-left:2px solid var(--border)}
.tl-item{position:relative;margin-bottom:18px}
.tl-item::before{content:"";position:absolute;left:-43px;top:4px;width:14px;height:14px;border-radius:50%;background:var(--gold);border:3px solid var(--bg);box-shadow:0 0 0 1px var(--gold)}
.tl-item h4{margin:0 0 4px;color:var(--navy)}

/* quiz */
.quiz{background:var(--card);border:1px solid var(--border);border-radius:6px;padding:20px;margin:16px 0;box-shadow:var(--shadow)}
.quiz p.q{font-weight:700;margin-top:0;font-family:'Playfair Display',serif;font-size:1.08rem;color:var(--navy)}
.quiz .opts label{display:block;background:#efe6d6;border:1px solid var(--border);border-radius:4px;padding:10px 14px;margin:6px 0;cursor:pointer;transition:.12s;font-size:.9rem}
.quiz .opts label:hover{background:#e3d8c2}
.quiz .opts input{margin-right:10px}
.quiz button{background:var(--teal);color:#fff;border:0;border-radius:4px;padding:9px 20px;font-weight:600;cursor:pointer;margin-top:8px;font-family:'JetBrains Mono',monospace;font-size:.78rem;letter-spacing:.06em;text-transform:uppercase}
.quiz button:hover{background:var(--navy)}
.quiz .result{margin-top:10px;font-weight:700;padding:10px;border-radius:4px;display:none;font-size:.9rem}
.quiz .result.correct{display:block;background:#dde7da;color:var(--green)}
.quiz .result.wrong{display:block;background:#ecdbd4;color:var(--red)}

footer{background:var(--navy);color:#cfddd2;text-align:center;padding:26px 0;margin-top:30px;font-size:.8rem;font-family:'JetBrains Mono',monospace;letter-spacing:.03em}
.toc{columns:2;gap:30px}
.toc li{margin-bottom:6px;break-inside:avoid}
@media(max-width:700px){.toc{columns:1}.barlabel{width:140px;font-size:.74rem}}
.flow{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin:14px 0}
.flow .step{background:var(--card);border:1px solid var(--border);border-left:3px solid var(--teal);border-radius:4px;padding:10px 16px;font-weight:600;color:var(--navy2);font-size:.86rem}