@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=IBM+Plex+Mono:wght@400;500;600&display=swap');

:root {
  --bg:#0c0c10; --bg-elev:#131318; --surface:#1a1a20; --surface-2:#22222a; --surface-3:#2a2a34;
  --border:#2c2c36; --border-soft:#1d1d26; --text:#f0f0f5; --text-2:#90909c; --muted:#5e5e6c; --dim:#42424e;
  --accent:#e05c00; --accent-soft:rgba(224,92,0,0.10);
  --teal:#00a87a; --amber:#e08000; --green:#2fa15c; --coral:#e04545;
  --blue:#3b82e8; --purple:#8855f5; --rose:#e03f78; --gold:#d89800;
  --shadow:0 2px 16px rgba(0,0,0,0.4); --radius:10px; --radius-sm:6px;
}

*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;scroll-padding-top:80px}
body{font-family:'Inter',system-ui,sans-serif;background:var(--bg);color:var(--text);min-height:100vh;line-height:1.65}

/* NAVBAR */
.navbar{position:fixed;top:0;left:0;right:0;background:var(--bg-elev);border-bottom:1px solid var(--border);z-index:1000;padding:11px 0}
.nav-inner{max-width:1400px;margin:0 auto;padding:0 24px;display:flex;align-items:center;justify-content:space-between;gap:16px}
.nav-brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:15px;text-decoration:none;color:var(--text)}
.nav-logo{width:32px;height:32px;border-radius:6px;background:var(--accent);display:grid;place-items:center;font-family:'IBM Plex Mono',monospace;font-weight:600;color:#fff;font-size:11px}
.nav-links,.nav-tabs{display:flex;gap:2px;flex:1;justify-content:center;overflow-x:auto;scrollbar-width:none}
.nav-links::-webkit-scrollbar,.nav-tabs::-webkit-scrollbar{display:none}
.nav-link,.nav-tab{background:transparent;border:none;color:var(--muted);padding:7px 13px;border-radius:5px;font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:500;cursor:pointer;transition:all 0.15s;white-space:nowrap;text-decoration:none;display:inline-block}
.nav-link:hover,.nav-link.active,.nav-tab:hover,.nav-tab.active{color:var(--text);background:var(--surface)}
.nav-link.active,.nav-tab.active{color:var(--accent);font-weight:600}
.nav-actions{display:flex;gap:8px;align-items:center;flex-shrink:0}
.nav-mode{display:flex;gap:2px;background:var(--surface);padding:3px;border-radius:6px;border:1px solid var(--border)}
.mode-btn{background:transparent;border:none;color:var(--muted);padding:5px 10px;border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:11px;cursor:pointer;transition:all 0.15s;font-weight:500}
.mode-btn.active{background:var(--accent);color:#fff}

/* LAYOUT */
main{padding-top:68px}
.container{max-width:1100px;margin:0 auto;padding:40px 24px 80px}
.container-wide{max-width:1400px;margin:0 auto;padding:40px 24px 80px}

/* SECTION TRANSITIONS */
.section{display:none}
.section.active{display:block;animation:fadeIn 0.2s ease}
@keyframes fadeIn{from{opacity:0;transform:translateY(5px)}to{opacity:1;transform:translateY(0)}}

/* TYPOGRAPHY */
h1{font-size:clamp(26px,5vw,46px);font-weight:800;letter-spacing:-2px;line-height:1.1;margin-bottom:14px}
h2{font-size:clamp(18px,3vw,26px);font-weight:700;letter-spacing:-0.8px;margin:40px 0 14px;line-height:1.2;border-bottom:1px solid var(--border-soft);padding-bottom:10px}
h3{font-size:18px;font-weight:700;letter-spacing:-0.3px;margin:28px 0 10px}
h4{font-size:11px;font-weight:600;margin:18px 0 6px;color:var(--muted);font-family:'IBM Plex Mono',monospace;text-transform:uppercase;letter-spacing:0.8px}
p{margin-bottom:14px;color:var(--text-2);font-size:15px;line-height:1.7}
strong{color:var(--text);font-weight:600}
em{color:var(--accent);font-style:normal;font-weight:600}
ul,ol{margin:10px 0 16px 22px;color:var(--text-2);font-size:15px}
li{margin-bottom:5px;line-height:1.65}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
code{font-family:'IBM Plex Mono',monospace;background:var(--surface);padding:2px 6px;border-radius:4px;font-size:0.85em;color:var(--amber);border:1px solid var(--border)}
mark{background:rgba(220,152,0,0.18);color:var(--gold);padding:0 3px;border-radius:2px}

/* HERO */
.hero{text-align:center;padding:56px 20px 60px;background:var(--bg-elev);border:1px solid var(--border);border-top:3px solid var(--accent);border-radius:var(--radius);margin-bottom:48px}
.hero-tag{display:inline-block;background:var(--surface);color:var(--muted);border:1px solid var(--border);padding:4px 12px;border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:500;margin-bottom:20px;letter-spacing:0.3px}
.hero h1{color:var(--text)}
.hero p{font-size:16px;color:var(--text-2);max-width:620px;margin:0 auto 36px}
.hero-subtitle{font-size:16px;color:var(--text-2);max-width:660px;margin:0 0 32px;line-height:1.7}
.hero-stats{display:flex;flex-wrap:wrap;justify-content:center;gap:12px}
.hero-stat{background:var(--bg);border:1px solid var(--border);padding:14px 22px;border-radius:8px;min-width:110px;text-align:center}
.hero-stat-value{font-size:28px;font-weight:800;color:var(--accent);line-height:1;letter-spacing:-1px}
.hero-stat-label{font-family:'IBM Plex Mono',monospace;font-size:10px;color:var(--muted);margin-top:5px;text-transform:uppercase;letter-spacing:0.5px}

/* CARDS */
.card{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);padding:22px;margin-bottom:14px;transition:border-color 0.2s}
.card:hover{border-color:var(--accent)}
.card-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px;margin:20px 0}
.topic-card{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);padding:22px;cursor:pointer;transition:all 0.2s;position:relative;overflow:hidden}
.topic-card:hover{border-color:var(--accent);box-shadow:var(--shadow)}
.topic-card::before{content:'';position:absolute;top:0;left:0;right:0;height:2px;background:var(--bar-color,var(--accent))}
.topic-num{font-family:'IBM Plex Mono',monospace;font-size:10px;color:var(--muted);text-transform:uppercase;letter-spacing:1px;margin-bottom:7px}
.topic-title-card{font-size:16px;font-weight:700;letter-spacing:-0.3px;margin-bottom:8px;color:var(--text)}
.topic-desc{font-size:13px;color:var(--muted);line-height:1.6}
.topic-meta{display:flex;gap:12px;margin-top:12px;padding-top:12px;border-top:1px solid var(--border-soft)}
.topic-meta-item{font-family:'IBM Plex Mono',monospace;font-size:10px;color:var(--muted)}
.topic-meta-item span{color:var(--text-2);font-weight:600}

/* CONCEPT BOXES */
.concept-box{background:var(--bg-elev);border:1px solid var(--border);border-left:3px solid var(--accent);padding:16px 20px;border-radius:var(--radius);margin:18px 0}
.concept-box.note{border-left-color:var(--blue)}
.concept-box.warn{border-left-color:var(--amber)}
.concept-box.danger{border-left-color:var(--coral)}
.concept-box.success{border-left-color:var(--green)}
.concept-box.tip{border-left-color:var(--teal)}
.concept-box-title{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:0.8px;color:var(--accent);margin-bottom:8px;font-weight:600}
.concept-box.note .concept-box-title{color:var(--blue)}
.concept-box.warn .concept-box-title{color:var(--amber)}
.concept-box.danger .concept-box-title{color:var(--coral)}
.concept-box.success .concept-box-title{color:var(--green)}
.concept-box.tip .concept-box-title{color:var(--teal)}

/* ANALOGIES */
.analogy{background:var(--surface);border:1px solid rgba(0,168,122,0.22);border-left:3px solid var(--teal);padding:14px 18px;border-radius:var(--radius);margin:14px 0;display:flex;gap:12px;align-items:flex-start}
.analogy-icon{font-size:20px;flex-shrink:0;line-height:1.4}
.analogy-text{color:var(--text-2);font-size:14px;line-height:1.65}
.analogy-text strong{color:var(--teal)}

/* TABLES */
.table-wrap{overflow-x:auto;margin:18px 0;border-radius:var(--radius);border:1px solid var(--border)}
table{width:100%;border-collapse:collapse;background:var(--bg-elev);font-size:14px}
th{background:var(--surface);color:var(--text);font-weight:600;text-align:left;padding:10px 14px;border-bottom:1px solid var(--border);font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:0.6px}
td{padding:10px 14px;border-bottom:1px solid var(--border-soft);color:var(--text-2);font-size:14px;line-height:1.55}
tr:last-child td{border-bottom:none}
tr:hover td{background:var(--surface);color:var(--text)}

/* FORMULAS */
.formula-block{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);padding:22px;margin:18px 0}
.formula-name{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:0.8px;color:var(--accent);margin-bottom:10px;font-weight:600}
.formula-eq{font-size:22px;color:var(--text);text-align:center;padding:18px;background:var(--surface);border-radius:var(--radius-sm);margin:10px 0;border:1px solid var(--border);overflow-x:auto}
.formula-eq .katex{color:var(--text)}
.formula-vars{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:7px;margin-top:10px}
.formula-var{background:var(--surface);padding:7px 10px;border-radius:5px;font-size:13px;border-left:2px solid var(--accent)}
.formula-var-symbol{font-family:'IBM Plex Mono',monospace;font-weight:600;color:var(--amber);margin-right:6px}

/* EXAMPLES */
.example{background:var(--bg-elev);border:1px solid var(--border);border-left:3px solid var(--blue);border-radius:var(--radius);padding:18px 22px;margin:18px 0}
.example-label{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:0.8px;color:var(--blue);font-weight:600;margin-bottom:8px}
.example-q{font-weight:600;font-size:15px;color:var(--text);margin-bottom:14px;padding-bottom:10px;border-bottom:1px solid var(--border)}
.example-step{margin:8px 0;padding-left:18px;position:relative;color:var(--text-2);font-size:14px;line-height:1.6}
.example-step::before{content:'→';position:absolute;left:0;color:var(--blue);font-weight:600}
.example-answer{margin-top:14px;padding:10px 14px;background:rgba(0,168,122,0.08);border-left:2px solid var(--teal);border-radius:4px;font-family:'IBM Plex Mono',monospace;color:var(--teal);font-weight:600;font-size:13px}

/* TRAP CARDS */
.trap-card{background:var(--bg-elev);border:1px solid rgba(224,69,69,0.22);border-left:3px solid var(--coral);border-radius:var(--radius);padding:18px;margin:14px 0}
.trap-tag{display:inline-block;background:var(--coral);color:white;padding:3px 10px;border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:10px;font-weight:600;text-transform:uppercase;margin-bottom:9px;letter-spacing:0.5px}
.trap-claim{color:var(--text);margin-bottom:10px;font-weight:500;font-size:15px}
.trap-truth{background:rgba(0,168,122,0.08);border-left:2px solid var(--teal);padding:9px 12px;border-radius:4px;color:var(--text-2);font-size:14px;line-height:1.6}
.trap-truth strong{color:var(--teal)}

/* PROCESS FLOW */
.process-flow{display:flex;align-items:flex-start;gap:0;overflow-x:auto;padding:4px 0 20px;margin:20px 0;scrollbar-width:thin}
.process-step{flex-shrink:0;background:var(--bg-elev);border:1px solid var(--border);border-top:2px solid var(--accent);border-radius:var(--radius);padding:16px 16px 14px;min-width:148px;max-width:195px;text-align:center;position:relative;margin-right:30px}
.process-step:last-child{margin-right:0}
.process-step:not(:last-child)::after{content:'›';position:absolute;right:-22px;top:16px;color:var(--muted);font-size:18px;font-weight:400;width:30px;text-align:center;line-height:1;pointer-events:none}
.process-step-num{display:inline-block;font-family:'IBM Plex Mono',monospace;font-size:9px;color:#fff;background:var(--accent);padding:2px 8px;border-radius:3px;margin-bottom:9px;font-weight:600;letter-spacing:0.5px}
.process-step-name{font-size:13px;font-weight:700;letter-spacing:-0.2px;color:var(--text);margin-bottom:6px;line-height:1.3}
.process-step-desc{font-size:11px;color:var(--muted);line-height:1.5}

/* TWO COLUMN */
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:20px;margin:18px 0}

/* INLINE TAGS */
.inline-list{display:flex;flex-wrap:wrap;gap:7px;margin:10px 0}
.tag{background:var(--surface);border:1px solid var(--border);color:var(--text-2);padding:4px 10px;border-radius:4px;font-size:12px;font-family:'IBM Plex Mono',monospace}

/* TABLE OF CONTENTS */
.toc{background:var(--bg-elev);border:1px solid var(--border);border-left:3px solid var(--accent);border-radius:var(--radius);padding:16px 20px;margin-bottom:28px}
.toc-title{font-family:'IBM Plex Mono',monospace;font-size:10px;color:var(--muted);text-transform:uppercase;letter-spacing:0.8px;margin-bottom:10px;font-weight:600}
.toc-list{display:grid;grid-template-columns:repeat(auto-fit,minmax(190px,1fr));gap:2px;list-style:none;margin:0}
.toc-list li{margin:0}
.toc-link{color:var(--text-2);text-decoration:none;font-size:13px;padding:5px 10px;border-radius:4px;display:block;transition:all 0.15s;border-left:2px solid transparent}
.toc-link:hover{background:var(--surface);color:var(--accent);border-left-color:var(--accent);text-decoration:none}

/* GLOSSARY */
.glossary-search-wrap,.glossary-search{position:sticky;top:68px;z-index:50;background:var(--bg);padding:14px 0;margin-bottom:20px}
.search-input-wrap{position:relative;max-width:680px;margin:0 auto}
.search-input{width:100%;background:var(--bg-elev);border:1px solid var(--border);border-radius:8px;padding:12px 44px 12px 18px;font-size:15px;font-family:'Inter',system-ui,sans-serif;color:var(--text);outline:none;transition:border-color 0.2s}
.search-input:focus{border-color:var(--accent)}
.search-input::placeholder{color:var(--muted)}
.search-icon{position:absolute;right:16px;top:50%;transform:translateY(-50%);color:var(--muted);font-size:16px;pointer-events:none}
#search-results-count{text-align:center;margin-top:7px;font-family:'IBM Plex Mono',monospace;font-size:11px;color:var(--muted);height:16px}
.filter-row{display:flex;gap:6px;flex-wrap:wrap;justify-content:center;margin-bottom:22px}
.filter-btn{padding:5px 12px;border-radius:4px;border:1px solid var(--border);background:var(--bg-elev);color:var(--muted);font-family:'IBM Plex Mono',monospace;font-size:11px;cursor:pointer;transition:all 0.15s;font-weight:500}
.filter-btn:hover{color:var(--text-2);border-color:var(--surface-3)}
.filter-btn.active{background:var(--accent);border-color:var(--accent);color:white;font-weight:600}
.glossary-section{margin-bottom:16px;border-radius:var(--radius);border:1px solid var(--border);overflow:hidden}
.glossary-section.hidden{display:none}
.glossary-header{padding:12px 18px;cursor:pointer;background:var(--surface);display:flex;justify-content:space-between;align-items:center;transition:background 0.15s}
.glossary-header:hover{background:var(--surface-2)}
.glossary-section.collapsed .glossary-grid{display:none}
.glossary-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(310px,1fr));gap:1px;background:var(--border)}
.term-item{background:var(--bg);padding:12px 15px;border-left:2px solid transparent;transition:all 0.15s}
.term-item:hover{background:var(--surface)}
.term-item.match{background:var(--accent-soft);border-left-color:var(--accent)}
.term-item.hidden{display:none}
.term-name{font-family:'IBM Plex Mono',monospace;font-size:12px;font-weight:600;margin-bottom:4px}
.term-def{font-size:13px;color:var(--text-2);line-height:1.6}
.no-results-msg{display:none;text-align:center;padding:60px 20px;color:var(--muted);font-family:'IBM Plex Mono',monospace}

/* DEFINITIONS PAGE — DIAGRAM BLOCKS */
.def-section{margin-bottom:60px;padding-bottom:40px;border-bottom:1px solid var(--border)}
.def-section:last-child{border-bottom:none}
.diagram-wrap{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);padding:24px;margin:20px 0;overflow-x:auto}
.diagram-wrap svg{display:block;max-width:100%;height:auto;margin:0 auto}
.diagram-caption{font-family:'IBM Plex Mono',monospace;font-size:11px;color:var(--muted);text-align:center;margin-top:10px;text-transform:uppercase;letter-spacing:0.5px}
.def-term-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:1px;background:var(--border);border-radius:var(--radius);overflow:hidden;margin:18px 0}
.def-term{background:var(--bg-elev);padding:16px 18px;border-left:2px solid var(--accent)}
.def-term-name{font-family:'IBM Plex Mono',monospace;font-size:12px;font-weight:600;color:var(--accent);margin-bottom:5px}
.def-term-def{font-size:14px;color:var(--text-2);line-height:1.6}
.def-term-note{font-size:12px;color:var(--muted);margin-top:5px;font-style:italic}

/* SVG DIAGRAM LABELS */
.diag-label{font-family:'IBM Plex Mono',monospace;font-size:11px;fill:#90909c}
.diag-title{font-family:'Inter',system-ui,sans-serif;font-size:13px;font-weight:700;fill:#f0f0f5}
.diag-accent{fill:#e05c00}
.diag-teal{fill:#00a87a}
.diag-amber{fill:#e08000}
.diag-coral{fill:#e04545}
.diag-green{fill:#2fa15c}
.diag-muted{fill:#5e5e6c}

/* LEARN/REVISE */
.learn-only,.revise-only{transition:opacity 0.2s}
body.revise-mode .learn-only{display:none}
body.revise-mode .analogy{display:none}
body.revise-mode .toc{display:none}

/* REVISE MODE */
body.revise-mode .mode-btn[data-mode="revise"].active{background:var(--amber);color:#0c0c10}

/* MODE FLASH OVERLAY */
@keyframes modeFlash{0%{opacity:0}15%{opacity:1}100%{opacity:0}}
.mode-flash{position:fixed;inset:0;pointer-events:none;z-index:9999;animation:modeFlash 0.8s ease-out forwards}
.mode-flash.learn{box-shadow:inset 0 0 0 2px var(--accent)}
.mode-flash.revise{box-shadow:inset 0 0 0 2px var(--amber)}

/* MODE TOAST */
@keyframes toastIn{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}
@keyframes toastOut{from{opacity:1;transform:translateY(0)}to{opacity:0;transform:translateY(6px)}}
.mode-toast{position:fixed;bottom:28px;right:28px;padding:9px 16px;border-radius:6px;font-family:'IBM Plex Mono',monospace;font-size:12px;font-weight:600;z-index:9998;pointer-events:none;letter-spacing:0.3px;animation:toastIn 0.2s ease forwards}
.mode-toast.learn{background:var(--accent);color:white}
.mode-toast.revise{background:var(--amber);color:#0c0c10}
.mode-toast.fade-out{animation:toastOut 0.3s ease forwards}

/* PREV / NEXT TOPIC NAV */
.topic-nav{display:flex;justify-content:space-between;align-items:center;margin-top:56px;padding-top:24px;border-top:1px solid var(--border)}
.topic-nav-btn{background:var(--bg-elev);border:1px solid var(--border);color:var(--text-2);padding:9px 16px;border-radius:var(--radius-sm);font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:500;cursor:pointer;transition:all 0.15s;display:flex;align-items:center;gap:8px}
.topic-nav-btn:hover{border-color:var(--accent);color:var(--accent)}
.topic-nav-btn.disabled{opacity:0.25;pointer-events:none}

/* SECTION ACCENT STRIP */
.section-accent{height:2px;position:relative;margin:0;border:none}
#t1 .section-accent{background:var(--muted)}
#t2 .section-accent{background:var(--amber)}
#t3 .section-accent{background:var(--teal)}
#t4 .section-accent{background:var(--green)}
#t5 .section-accent{background:var(--blue)}
#t6 .section-accent{background:var(--purple)}
#t7 .section-accent{background:var(--coral)}
#t8 .section-accent{background:var(--gold)}
#t9 .section-accent{background:var(--rose)}
#t10 .section-accent{background:#cc44cc}

/* RESPONSIVE */
@media(max-width:768px){
  .nav-links,.nav-tabs{gap:0}.nav-link,.nav-tab{padding:6px 8px;font-size:10px}.two-col{grid-template-columns:1fr}.container{padding:24px 16px 60px}.hero{padding:36px 14px 48px}.nav-mode{display:none}.topic-nav-btn{padding:8px 12px;font-size:10px}
}

/* SCROLLBAR */
::-webkit-scrollbar{width:6px;height:6px}::-webkit-scrollbar-track{background:var(--bg)}::-webkit-scrollbar-thumb{background:var(--surface-2);border-radius:3px}::-webkit-scrollbar-thumb:hover{background:var(--surface-3)}

/* TOPIC COLOUR VARS */
.topic-1{--bar-color:#5e5e6c}.topic-2{--bar-color:var(--amber)}.topic-3{--bar-color:var(--teal)}.topic-4{--bar-color:var(--green)}.topic-5{--bar-color:var(--blue)}.topic-6{--bar-color:var(--purple)}.topic-7{--bar-color:var(--coral)}.topic-8{--bar-color:var(--gold)}.topic-9{--bar-color:var(--rose)}.topic-10{--bar-color:#cc44cc}

/* ── HUB BACK LINK ───────────────────────────── */
.nav-hub-link{font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:500;color:var(--muted);text-decoration:none;white-space:nowrap;padding:5px 10px;border-radius:5px;border:1px solid var(--border);transition:all 0.15s;flex-shrink:0}
.nav-hub-link:hover{color:var(--accent);border-color:var(--accent);background:var(--accent-soft);text-decoration:none}

/* ── FOCUSED FLASHCARD SESSION ───────────────── */
#fc-session{padding:4px 0 40px}
.fc-config{display:flex;flex-direction:column;gap:10px;margin-bottom:28px;padding:16px 20px;background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius)}
.fc-config-row{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.fc-config-label{font-family:'IBM Plex Mono',monospace;font-size:10px;font-weight:600;color:var(--muted);text-transform:uppercase;letter-spacing:0.6px;min-width:44px}
.fc-filter-btn{background:var(--bg);border:1px solid var(--border);color:var(--muted);padding:4px 10px;border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:10px;font-weight:500;cursor:pointer;transition:all 0.15s}
.fc-filter-btn:hover,.fc-filter-btn.active{color:var(--accent);border-color:var(--accent);background:var(--accent-soft)}
.fc-qty-select{background:var(--bg);border:1px solid var(--border);color:var(--text-2);padding:4px 8px;border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:10px;cursor:pointer;outline:none}
.fc-reshuffle-btn,.fc-exit-btn{background:var(--bg);border:1px solid var(--border);color:var(--muted);padding:5px 12px;border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:10px;font-weight:500;cursor:pointer;transition:all 0.15s}
.fc-reshuffle-btn:hover{border-color:var(--teal);color:var(--teal)}
.fc-exit-btn{margin-left:auto}
.fc-exit-btn:hover{border-color:var(--text-2);color:var(--text-2)}
.fc-viewport{width:100%;max-width:600px;margin:0 auto;height:260px;perspective:1200px;cursor:pointer;user-select:none}
.fc-card-inner{position:relative;width:100%;height:100%;transform-style:preserve-3d;transition:transform 0.4s ease}
.fc-card-inner.flipped{transform:rotateY(180deg)}
.fc-card-face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;border-radius:var(--radius);padding:28px 32px;display:flex;flex-direction:column;justify-content:center;border:1px solid var(--border)}
.fc-front{background:var(--bg-elev)}
.fc-back{background:var(--surface);border-color:var(--accent);transform:rotateY(180deg)}
.fc-topic-label{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:0.8px;margin-bottom:14px}
.fc-term-text{font-size:clamp(18px,3vw,26px);font-weight:700;letter-spacing:-0.5px;color:var(--text);line-height:1.3}
.fc-tap-hint{font-family:'IBM Plex Mono',monospace;font-size:9px;color:var(--dim);margin-top:auto;padding-top:14px}
.fc-back-term{font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:600;margin-bottom:10px}
.fc-def-text{font-size:14px;color:var(--text-2);line-height:1.65;overflow:hidden;display:-webkit-box;-webkit-line-clamp:6;-webkit-box-orient:vertical}
.fc-nav-row{display:flex;align-items:center;justify-content:space-between;max-width:600px;margin:18px auto 0;gap:16px}
.fc-nav-btn{background:var(--bg-elev);border:1px solid var(--border);color:var(--text-2);padding:10px 22px;border-radius:var(--radius-sm);font-family:'IBM Plex Mono',monospace;font-size:12px;font-weight:500;cursor:pointer;transition:all 0.15s}
.fc-nav-btn:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}
.fc-nav-btn:disabled{opacity:0.25;cursor:default}
.fc-counter-display{font-family:'IBM Plex Mono',monospace;font-size:13px;color:var(--muted)}
.fc-progress-wrap{max-width:600px;margin:12px auto 0;height:2px;background:var(--border-soft);border-radius:1px;overflow:hidden}
#fc-progress-bar{height:100%;background:var(--accent);border-radius:1px;transition:width 0.3s ease;width:0%}
.fc-open-btn{background:var(--bg-elev);border:1px solid var(--border);color:var(--muted);padding:7px 16px;border-radius:6px;font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:500;cursor:pointer;transition:all 0.15s;margin-bottom:18px;display:inline-flex;align-items:center;gap:7px}
.fc-open-btn:hover{border-color:var(--accent);color:var(--accent);background:var(--accent-soft)}

/* ── PRACTICE PROBLEMS ───────────────────── */
.problem-card{background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);padding:22px;margin:14px 0;position:relative}
.problem-header{display:flex;align-items:flex-start;justify-content:space-between;gap:12px;margin-bottom:14px}
.problem-tag{display:inline-block;background:var(--coral);color:white;padding:3px 10px;border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:10px;font-weight:600;text-transform:uppercase;letter-spacing:0.5px;flex-shrink:0}
.problem-q{font-weight:600;color:var(--text);line-height:1.55;padding-bottom:12px;border-bottom:1px dashed var(--border-soft);font-size:15px}
.problem-parts{margin-top:10px;color:var(--text-2);font-size:14px}
.problem-parts li{margin:5px 0}
.reveal-btn{background:transparent;border:1px solid var(--accent);color:var(--accent);padding:7px 16px;border-radius:5px;font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:600;cursor:pointer;transition:all 0.2s;white-space:nowrap;flex-shrink:0}
.reveal-btn:hover{background:var(--accent-soft)}
.reveal-btn.revealed{border-color:var(--teal);color:var(--teal)}
.problem-answer{display:none;margin-top:16px;padding:14px 16px;background:rgba(0,168,122,0.08);border-left:3px solid var(--teal);border-radius:4px}
.problem-answer.visible{display:block;animation:fadeIn 0.2s ease}
.ans-step{margin:6px 0;padding-left:18px;position:relative;color:var(--text-2);font-size:14px;line-height:1.5}
.ans-step::before{content:'→';position:absolute;left:0;color:var(--teal);font-weight:600}
.ans-final{margin-top:12px;padding:8px 14px;background:var(--accent-soft);border-left:3px solid var(--accent);border-radius:4px;font-family:'IBM Plex Mono',monospace;font-size:13px;color:var(--accent);font-weight:600}

/* ── MINI FLASHCARD GRID ─────────────────── */
.flashcard-bar{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-bottom:16px}
.fc-toggle-btn{background:var(--bg-elev);border:1px solid var(--border);color:var(--muted);padding:7px 14px;border-radius:var(--radius);font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:500;cursor:pointer;transition:all 0.15s}
.fc-toggle-btn.active{border-color:var(--accent);color:var(--accent);background:var(--accent-soft)}
.fc-counter{font-family:'IBM Plex Mono',monospace;font-size:11px;color:var(--muted)}
.fc-grid{display:none;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:12px;margin:16px 0}
.fc-grid.visible{display:grid}
.flashcard{height:150px;perspective:900px;cursor:pointer}
.flashcard-inner{position:relative;width:100%;height:100%;transform-style:preserve-3d;transition:transform 0.35s ease}
.flashcard.flipped .flashcard-inner{transform:rotateY(180deg)}
.fc-topic{font-family:'IBM Plex Mono',monospace;font-size:9px;text-transform:uppercase;letter-spacing:0.8px;margin-bottom:7px}
.fc-term{font-family:'Inter',system-ui,sans-serif;font-weight:700;font-size:13px;color:var(--text);line-height:1.35}
.fc-hint{font-family:'IBM Plex Mono',monospace;font-size:9px;color:var(--dim);margin-top:auto;padding-top:8px}
.fc-def{font-size:12px;color:var(--text-2);line-height:1.5;overflow:hidden;display:-webkit-box;-webkit-line-clamp:5;-webkit-box-orient:vertical}
.glossary-list-view{display:block}
.glossary-list-view.hidden{display:none}
.fc-filter-row{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:12px}

/* ── PROGRESS TRACKING ───────────────────── */
.topic-card{position:relative}
.topic-card.visited{border-color:rgba(0,168,122,0.40)}
.topic-card.visited .topic-num::after{content:' ✓';color:var(--teal)}
.progress-row{display:flex;align-items:center;gap:10px;margin-bottom:20px;font-family:'IBM Plex Mono',monospace;font-size:11px;color:var(--muted)}
.progress-track{flex:1;height:4px;background:var(--border-soft);border-radius:2px;overflow:hidden}
.progress-fill{height:100%;background:var(--teal);border-radius:2px;transition:width 0.5s ease;width:0%}

/* ── PRINT ───────────────────────────────── */
@media print{
  .navbar,.nav-mode,.topic-nav,.mode-toast,.mode-flash,.toc{display:none!important}
  .section{display:block!important;page-break-before:always}
  #home,#glossary,#traps,#problems{display:none!important}
  main{padding-top:0}
  body{background:white;color:#111;font-size:11pt}
  .formula-block,.example{break-inside:avoid;border:1px solid #ccc;background:#f9f9f9}
  .formula-eq{background:#f0f0f0;color:#111;border:1px solid #ccc;font-size:14pt}
  h1,h2{color:#111}
  .concept-box{border:1px solid #ccc;background:#f9f9f9}
}

/* ── SUBPAGES: one page per section, dot pager ── */
.section.paged .subpage{display:none}
.section.paged .subpage.active{display:block;animation:fadeIn 0.2s ease}
body.revise-mode .section.paged .subpage,body.single-page .section.paged .subpage{display:block}
.section.paged .container,.section.paged .container-wide{padding-bottom:130px}
body.single-page .section.paged .container,body.single-page .section.paged .container-wide{padding-bottom:90px}
.subpage [id]{scroll-margin-top:88px}
.sub-foot{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:48px;padding-top:22px;border-top:1px solid var(--border)}
.sub-foot .topic-nav-btn{max-width:48%;text-align:left;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.sub-foot .sub-next{margin-left:auto;text-align:right;border-color:var(--accent);color:var(--accent)}
.sub-foot .sub-next:hover{background:var(--accent-soft,rgba(255,255,255,0.05))}
body.revise-mode .sub-foot,body.single-page .sub-foot{display:none}

.subpager{position:fixed;left:50%;bottom:16px;z-index:900;transform:translate(-50%,24px);opacity:0;pointer-events:none;transition:opacity .2s,transform .2s;display:flex;flex-direction:column;align-items:center;gap:5px;padding:8px 14px 9px;background:rgba(19,19,24,0.92);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border);border-radius:22px;box-shadow:0 6px 24px rgba(0,0,0,0.45);max-width:calc(100vw - 20px)}
.subpager.show{opacity:1;transform:translate(-50%,0);pointer-events:auto}
body.revise-mode .subpager,body.revise-mode .layout-fab{display:none}
.subpager-top{display:flex;align-items:center;justify-content:center;gap:10px;max-width:100%}
.subpager-mode{flex-shrink:0;font-family:'IBM Plex Mono',monospace;font-size:9.5px;letter-spacing:.3px;color:var(--muted);background:none;border:1px solid var(--border);border-radius:10px;padding:1px 8px;cursor:pointer;transition:color .15s,border-color .15s}
.subpager-mode:hover{color:var(--accent);border-color:var(--accent)}
.layout-fab{position:fixed;left:50%;bottom:16px;z-index:900;transform:translate(-50%,24px);opacity:0;pointer-events:none;transition:opacity .2s,transform .2s;font-family:'IBM Plex Mono',monospace;font-size:11px;color:var(--text-2);background:rgba(19,19,24,0.92);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border);border-radius:20px;padding:8px 16px;cursor:pointer;box-shadow:0 6px 24px rgba(0,0,0,0.45)}
.layout-fab.show{opacity:1;transform:translate(-50%,0);pointer-events:auto}
.layout-fab:hover{color:var(--accent);border-color:var(--accent)}
.subpager-label{font-family:'IBM Plex Mono',monospace;font-size:10px;letter-spacing:.3px;color:var(--text-2);max-width:min(520px,calc(100vw - 70px));white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.subpager-count{color:var(--accent);font-weight:600;margin-right:8px}
.subpager-row{display:flex;align-items:center;gap:4px}
.subpager-dots{display:flex;align-items:center;gap:8px;padding:0 4px}
.subpager-dots.dense{gap:5px}
.subdot{position:relative;width:10px;height:10px;padding:0;border-radius:50%;border:1.5px solid var(--dim);background:transparent;cursor:pointer;transition:width .2s,background .2s,border-color .2s,transform .15s}
.subdot::after{content:'';position:absolute;inset:-8px -4px}
.subdot.visited{border-color:var(--accent);background:var(--accent);opacity:.45}
.subdot:hover{border-color:var(--accent);transform:scale(1.25)}
.subdot.active{width:26px;border-radius:6px;border-color:var(--accent);background:var(--accent);opacity:1;transform:none}
.subpager-dots.dense .subdot.active{width:20px}
.subpager-arrow{width:30px;height:30px;padding:0 0 2px;border:0;border-radius:50%;background:none;color:var(--text-2);font-size:20px;line-height:1;cursor:pointer;transition:color .15s,background .15s}
.subpager-arrow:hover:not(:disabled){color:var(--accent);background:var(--surface)}
.subpager-arrow:disabled{opacity:.22;cursor:default}
@media(max-width:768px){
  .subpager{bottom:10px;padding:7px 10px 8px}
  .subpager-dots{gap:6px}
  .sub-foot{flex-direction:column-reverse;align-items:stretch}
  .sub-foot .topic-nav-btn{max-width:none;text-align:center}
}
@media print{.subpager,.sub-foot,.layout-fab{display:none}.section.paged .subpage{display:block}}

/* ── TERM PREVIEWS (terms.js) ────────────── */
.gl-term{text-decoration:underline dotted;text-decoration-color:var(--muted);text-decoration-color:color-mix(in srgb,var(--accent) 70%,transparent);text-decoration-thickness:2px;text-underline-offset:4px;text-decoration-skip-ink:none;cursor:help;border-radius:2px;transition:text-decoration-color .15s,background .15s,color .15s}
.gl-term:hover,.gl-term:focus-visible{text-decoration-color:var(--accent);text-decoration-style:solid;outline:none}
.gl-term:focus-visible{background:var(--accent-soft)}
.tp-card{position:absolute;top:0;left:0;z-index:950;width:360px;max-width:calc(100vw - 16px);background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 14px 44px rgba(0,0,0,0.6);opacity:0;visibility:hidden;transform:translateY(4px);transition:opacity .16s ease,transform .16s ease,visibility 0s linear .16s;text-align:left;line-height:1.55}
.tp-card.wide{width:460px}
.tp-card.above{transform:translateY(-4px)}
.tp-card.open{opacity:1;visibility:visible;transform:none;transition:opacity .16s ease,transform .16s ease,visibility 0s}
.tp-arrow{position:absolute;top:-6px;width:10px;height:10px;background:var(--bg-elev);border-left:1px solid var(--border);border-top:1px solid var(--border);transform:rotate(45deg)}
.tp-card.above .tp-arrow{top:auto;bottom:-6px;transform:rotate(225deg)}
.tp-body{padding:14px 16px 12px;max-height:min(520px,62vh);overflow-y:auto;scrollbar-width:thin}
.tp-topic{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:.8px;margin-bottom:4px}
.tp-title{font-size:15px;font-weight:700;letter-spacing:-.2px;color:var(--text);margin-bottom:5px}
.tp-def{font-size:13.5px;color:var(--text-2)}
.tp-cmp{margin-top:12px;padding-top:11px;border-top:1px solid var(--border-soft)}
.tp-cmp-title{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:.8px;color:var(--text-2);margin-bottom:6px}
.tp-cmp-title span{color:var(--muted);text-transform:none}
.tp-cmp table{width:100%;border-collapse:collapse;font-size:12px;line-height:1.45}
.tp-cmp th,.tp-cmp td{padding:5px 6px;text-align:left;vertical-align:top;border-bottom:1px solid var(--border-soft);background:none}
.tp-cmp tr:last-child td{border-bottom:none}
.tp-cmp th{font-size:11.5px;font-weight:600;color:var(--text-2)}
.tp-cmp td{color:var(--text-2)}
.tp-cmp td:first-child{font-family:'IBM Plex Mono',monospace;font-size:10px;color:var(--muted);width:24%;padding-left:0}
.tp-cmp .is-self{color:var(--text)}
.tp-cmp th.is-self{color:var(--accent)}
.tp-foot{display:flex;justify-content:space-between;align-items:center;gap:10px;padding:8px 16px;border-top:1px solid var(--border-soft);background:var(--surface);border-radius:0 0 var(--radius) var(--radius)}
.tp-foot button{background:none;border:none;padding:0;color:var(--accent);font-family:'IBM Plex Mono',monospace;font-size:11px;font-weight:500;cursor:pointer}
.tp-foot button:hover{text-decoration:underline}
.tp-foot span{font-family:'IBM Plex Mono',monospace;font-size:10.5px;color:var(--muted)}
.tp-flash{animation:tpFlash 2.4s ease-out}
@keyframes tpFlash{0%,35%{background:rgba(216,152,0,0.32);box-shadow:0 0 0 3px rgba(216,152,0,0.32)}100%{background:transparent;box-shadow:0 0 0 3px transparent}}
.tp-flash-wrap{border-radius:2px}

/* glossary entries: click to expand, list mentions */
#glossary .term-item{cursor:pointer;position:relative}
#glossary .term-item::after{content:'+';position:absolute;top:10px;right:13px;font-family:'IBM Plex Mono',monospace;font-size:13px;color:var(--dim);opacity:0;transition:opacity .15s}
#glossary .term-item:hover::after,#glossary .term-item:focus-visible::after{opacity:1}
#glossary .term-item.expanded::after{content:'−';opacity:1;color:var(--muted)}
#glossary .term-item:focus-visible{outline:1px solid var(--accent);outline-offset:-1px}
#glossary .term-item.expanded{grid-column:1/-1;background:var(--surface);border-left-color:var(--accent);padding:16px 20px;cursor:default}
#glossary .term-item.expanded .term-name{cursor:pointer}
#glossary .term-item.expanded .term-def{font-size:14px;color:var(--text);max-width:820px}
.tp-panel{margin-top:14px;padding-top:14px;border-top:1px solid var(--border);animation:fadeIn .2s ease}
.tp-panel .tp-cmp{margin:0 0 16px;padding:0;border:none;max-width:820px}
.tp-panel .tp-cmp table{font-size:13px}
.tp-mentions-label{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:.8px;color:var(--muted);margin-bottom:8px}
.tp-mentions{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:8px}
.tp-mention{display:flex;flex-direction:column;gap:4px;text-align:left;background:var(--bg-elev);border:1px solid var(--border);border-radius:var(--radius-sm);padding:10px 12px;cursor:pointer;color:inherit;font:inherit;transition:border-color .15s,background .15s}
.tp-mention:hover,.tp-mention:focus-visible{border-color:var(--accent);background:var(--bg);outline:none}
.tp-m-where{font-family:'IBM Plex Mono',monospace;font-size:10.5px;color:var(--muted);line-height:1.4}
.tp-m-where b{color:var(--text-2);font-weight:600}
.tp-m-snip{font-size:12.5px;color:var(--text-2);line-height:1.5}
.tp-m-snip mark{background:none;color:var(--text);font-weight:600;padding:0}
.tp-panel:not(.show-all) .tp-extra{display:none}
.tp-more{margin-top:8px;background:none;border:1px solid var(--border);border-radius:var(--radius-sm);color:var(--text-2);font-family:'IBM Plex Mono',monospace;font-size:11px;padding:6px 12px;cursor:pointer}
.tp-more:hover{border-color:var(--accent);color:var(--accent)}
@media(max-width:768px){
  .tp-card,.tp-card.wide{width:calc(100vw - 16px)}
  .tp-mentions{grid-template-columns:1fr}
}
@media print{.tp-card{display:none!important}.gl-term{text-decoration:none}}
/* highlight lookups for non-glossary text */
.tp-topic:empty{display:none}
.tp-desc{font-family:'IBM Plex Mono',monospace;font-size:10.5px;color:var(--muted);margin:-2px 0 6px}
.tp-senses{margin:2px 0 0 18px;font-size:13px;color:var(--text-2)}
.tp-senses li{margin:3px 0}
.tp-senses i{color:var(--muted);font-style:normal;font-family:'IBM Plex Mono',monospace;font-size:10.5px;margin-right:4px}
.tp-related{margin-top:12px;padding-top:11px;border-top:1px solid var(--border-soft)}
.tp-body>.tp-related:first-child,.tp-topic+.tp-related{margin-top:0;padding-top:0;border-top:none}
.tp-rel-label{font-family:'IBM Plex Mono',monospace;font-size:10px;text-transform:uppercase;letter-spacing:.8px;color:var(--muted);margin-bottom:6px}
.tp-rel{display:block;width:100%;text-align:left;background:none;border:1px solid transparent;border-radius:var(--radius-sm);padding:6px 8px;margin:0 -8px;width:calc(100% + 16px);cursor:pointer;color:inherit;font:inherit;transition:background .15s,border-color .15s}
.tp-rel:hover,.tp-rel:focus-visible{background:var(--surface);border-color:var(--border);outline:none}
.tp-rel-name{display:block;font-family:'IBM Plex Mono',monospace;font-size:11.5px;font-weight:600}
.tp-rel-def{display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;font-size:12px;color:var(--text-2);line-height:1.45}
.tp-foot a{color:var(--accent);font-family:'IBM Plex Mono',monospace;font-size:11px;text-decoration:none}
.tp-foot a:hover{text-decoration:underline}
.tp-loading{display:flex;gap:5px;padding:8px 0 4px}
.tp-loading span{width:6px;height:6px;border-radius:50%;background:var(--dim);animation:tpDot 1s infinite ease-in-out}
.tp-loading span:nth-child(2){animation-delay:.15s}.tp-loading span:nth-child(3){animation-delay:.3s}
@keyframes tpDot{0%,80%,100%{opacity:.3;transform:scale(.8)}40%{opacity:1;transform:scale(1)}}
.tp-related+.tp-ext{margin-top:12px;padding-top:11px;border-top:1px solid var(--border-soft)}