:root{
  --paper: #f6f1e4;
  --paper-2: #ede4cf;
  --card: #fdfaf1;
  --ink: #1a2533;
  --ink-soft: #41506a;
  --ink-faint: #6b7889;
  --line: #d4c8a6;
  --line-soft: #e3d8b8;
  --accent: #b5842a;
  --accent-2: #2f6f6a;
  --accent-soft: #f0e1b5;
  --hl-yellow: #fff3a3;
  --hl-green:  #c9f0c2;
  --hl-pink:   #ffd6e0;
  --hl-blue:   #cfe6ff;
  --danger: #a64545;
  --success: #2f8a52;
  --shadow: 0 4px 14px rgba(28,43,58,.07), 0 1px 2px rgba(28,43,58,.05);
  --shadow-lg: 0 12px 32px rgba(28,43,58,.10);
  --radius: 12px;
  --sidebar-w: 300px;
  --reader-w: 760px;
  --rhythm: 1.8;
  --fs-base: 17.5px;
}
html[data-theme="dark"]{
  --paper: #14171d;
  --paper-2: #1b1f27;
  --card: #20242d;
  --ink: #ece6d6;
  --ink-soft: #b3ad9b;
  --ink-faint: #807a6c;
  --line: #353c48;
  --line-soft: #2a313d;
  --accent: #e0a93f;
  --accent-2: #5cbab2;
  --accent-soft: #2c2410;
  --hl-yellow: #665918;
  --hl-green:  #2d5530;
  --hl-pink:   #6b2a3a;
  --hl-blue:   #1f4a73;
  --shadow: 0 4px 16px rgba(0,0,0,.4);
  --shadow-lg: 0 12px 36px rgba(0,0,0,.55);
}
*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:'Hind','Noto Sans Devanagari',sans-serif;
  font-size:var(--fs-base);
  line-height:var(--rhythm);
  transition:background .3s ease, color .3s ease, font-size .15s ease, line-height .15s ease;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
h1,h2,h3,h4,.display{font-family:'Poppins','Tiro Devanagari Hindi',sans-serif;color:var(--ink);letter-spacing:-.2px;}
.mono{font-family:'JetBrains Mono',monospace;}

/* ---------- layout shell ---------- */
.app{display:grid;grid-template-columns:var(--sidebar-w) 1fr;min-height:100vh;}

/* ---------- top bar ---------- */
.progress-shell{
  position:sticky;top:0;z-index:40;
  min-height:44px;
  background:color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
  border-bottom:1px solid var(--line);
  padding:5px 14px;
  display:flex;align-items:center;gap:9px;
  grid-column:1/-1;
}
.topbar-title{
  flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;
  font-family:'Poppins',sans-serif;font-size:14px;font-weight:700;color:var(--ink);
}
.section-indicator{
  flex:0 1 420px;min-width:0;
  display:flex;align-items:center;gap:7px;
  padding:4px 10px;border:1px solid var(--line-soft);border-radius:99px;
  background:color-mix(in srgb,var(--card) 82%,transparent);
  color:var(--ink-soft);font-size:11px;font-weight:600;line-height:1.25;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis;
}
.section-indicator i{color:var(--accent-2);flex-shrink:0;}
.section-indicator span{overflow:hidden;text-overflow:ellipsis;}
.progress-label{
  font-family:'JetBrains Mono',monospace;
  font-size:12px;font-weight:700;color:var(--ink-soft);
  min-width:120px;text-align:right;white-space:nowrap;
}
.topbtn{
  border:1px solid var(--line);background:var(--card);color:var(--ink);
  width:32px;height:32px;border-radius:8px;cursor:pointer;
  display:flex;align-items:center;justify-content:center;
  font-size:13px;flex-shrink:0;
  transition:transform .15s ease, background .2s ease, border-color .2s;
}
.topbtn:hover{transform:translateY(-1px);background:var(--paper-2);border-color:var(--accent);}
.topbtn.active{background:var(--accent);color:#fff;border-color:var(--accent);}

@media(max-width:780px){
  .progress-shell{padding:4px 7px;gap:4px;}
  .topbar-title{display:none;}
  .section-indicator{flex:1;max-width:none;padding:4px 8px;font-size:10.5px;}
  .progress-label{font-size:10px;min-width:88px;}
  .topbtn{width:30px;height:30px;}
}

/* ---------- sidebar ---------- */
.sidebar{
  grid-row:2;
  border-right:1px solid var(--line);
  background:var(--paper-2);
  padding:20px 14px 30px;
  position:sticky;top:44px;
  height:calc(100vh - 44px);
  overflow-y:auto;
  display:flex;flex-direction:column;
  transition:transform .3s ease, opacity .2s ease;
}
.sidebar::-webkit-scrollbar{width:8px;}
.sidebar::-webkit-scrollbar-thumb{background:var(--line);border-radius:4px;}
.continent-picker{margin-bottom:6px;}
.continent-picker-label,.toc-group-label{
  font-family:'JetBrains Mono',monospace;font-size:11px;color:var(--ink-soft);
  text-transform:uppercase;letter-spacing:1px;margin:0 10px 8px;
}
.select-wrap{position:relative;margin:0 2px 6px;}
.select-wrap i.leading{position:absolute;left:13px;top:50%;transform:translateY(-50%);color:var(--accent);font-size:15px;pointer-events:none;}
.select-wrap i.chevron{position:absolute;right:13px;top:50%;transform:translateY(-50%);color:var(--ink-soft);font-size:12px;pointer-events:none;}
#continentSelect{
  width:100%;appearance:none;-webkit-appearance:none;
  background:var(--card);border:1.5px solid var(--line);color:var(--ink);
  font-family:'Hind',sans-serif;font-weight:600;font-size:15px;
  padding:12px 36px 12px 40px;border-radius:9px;cursor:pointer;
  transition:border-color .2s;
}
#continentSelect:hover{border-color:var(--accent);}
#continentSelect:focus{outline:2px solid var(--accent-2);outline-offset:1px;}

.toc-group-label{margin:18px 10px 8px;display:flex;align-items:center;justify-content:space-between;}
.toc-group-label--empty{opacity:.6;}
.soon-tag{
  font-family:'JetBrains Mono',monospace;font-size:9.5px;text-transform:none;letter-spacing:0;
  border:1px solid var(--line);border-radius:4px;padding:1px 5px;
}

.toc-toolbar{
  display:flex;gap:6px;margin:6px 4px 10px;
  padding:6px;border:1px solid var(--line-soft);border-radius:8px;
  background:var(--card);
}
.toc-tab{
  flex:1;border:none;background:transparent;color:var(--ink-soft);
  font-family:'Hind',sans-serif;font-size:12px;font-weight:600;
  padding:6px 4px;border-radius:5px;cursor:pointer;
  display:flex;align-items:center;justify-content:center;gap:4px;
  transition:background .15s, color .15s;
}
.toc-tab:hover{background:var(--paper-2);color:var(--ink);}
.toc-tab.active{background:var(--accent);color:#fff;}
.toc-tab .badge{
  font-family:'JetBrains Mono',monospace;font-size:10px;
  background:rgba(0,0,0,.15);padding:0 5px;border-radius:99px;
}
.toc-tab.active .badge{background:rgba(255,255,255,.25);}

.toc-link{
  display:flex;align-items:center;gap:10px;
  padding:9px 10px;border-radius:8px;
  color:var(--ink-soft);text-decoration:none;
  font-size:14.5px;font-weight:500;
  cursor:pointer;border:1px solid transparent;
  margin-bottom:2px;position:relative;
  transition:background .15s, color .15s, transform .1s;
}
.toc-link:hover{background:var(--card);color:var(--ink);transform:translateX(2px);}
.toc-link.active{
  background:var(--card);color:var(--ink);
  border-color:var(--line);box-shadow:var(--shadow);
}
.toc-link .num{
  font-family:'JetBrains Mono',monospace;font-size:11px;
  width:22px;height:22px;border-radius:5px;
  background:var(--paper-2);border:1px solid var(--line);
  display:flex;align-items:center;justify-content:center;flex-shrink:0;
}
.toc-link.active .num{background:var(--accent);color:#fff;border-color:var(--accent);}
.toc-link .title{flex:1;line-height:1.35;}
.toc-link .time{
  font-family:'JetBrains Mono',monospace;font-size:10px;
  color:var(--ink-faint);white-space:nowrap;
}
.toc-link .bookmark-icon,.toc-link .done-check{
  font-size:11px;opacity:0;flex-shrink:0;
}
.toc-link.is-bookmarked .bookmark-icon{opacity:1;color:var(--accent);}
.toc-link.is-done .done-check{opacity:1;color:var(--success);}
.toc-link.active .time{display:none;}

.sidebar-author{
  margin:auto 10px 0;
  padding-top:18px;
  border-top:1px solid var(--line);
  font-family:'JetBrains Mono',monospace;
  font-size:11px;
  color:var(--ink-soft);
  letter-spacing:.3px;
}
.sidebar-author span{
  display:block;
  color:var(--ink);
  font-family:'Poppins',sans-serif;
  font-size:13px;
  font-weight:700;
  letter-spacing:0;
  margin-top:3px;
}

/* ---------- main content ---------- */
main{grid-row:2;padding:40px 24px 140px;display:flex;justify-content:center;}
.reader{width:100%;max-width:var(--reader-w);}

.hero{
  padding:24px 0 32px;
  border-bottom:2px solid var(--line);
  margin-bottom:34px;
}
.hero .eyebrow{
  font-family:'JetBrains Mono',monospace;font-size:11px;letter-spacing:2px;
  color:var(--accent-2);text-transform:uppercase;margin-bottom:12px;display:block;font-weight:700;
}
.hero h1{
  font-size:clamp(26px,4vw,38px);margin:0 0 16px;line-height:1.2;font-weight:800;
  border-bottom:3px solid var(--accent);padding-bottom:14px;
}
.hero p{color:var(--ink-soft);margin:0;max-width:620px;font-size:16px;text-align:justify;}
.hero-meta{
  display:flex;flex-wrap:wrap;gap:14px;margin-top:18px;
  font-family:'JetBrains Mono',monospace;font-size:12px;color:var(--ink-faint);
}
.hero-meta span{display:flex;align-items:center;gap:6px;}
.hero-meta i{color:var(--accent);}

section.card{
  background:var(--card);
  border:1px solid var(--line);
  border-radius:var(--radius);
  padding:30px 34px 26px;
  margin-bottom:26px;
  box-shadow:var(--shadow);
  scroll-margin-top:74px;
  position:relative;
  transition:border-color .25s, box-shadow .25s, opacity .25s;
}
section.card.done{
  border-color:color-mix(in srgb,var(--success) 35%,var(--line));
  box-shadow:var(--shadow), 0 0 0 1px color-mix(in srgb,var(--success) 18%,transparent) inset;
}
section.card.is-bookmarked::before{
  content:"";position:absolute;left:-1px;top:18px;bottom:18px;width:3px;
  background:var(--accent);border-radius:2px;
}

section.card h2{
  font-size:clamp(22px,3vw,27px);margin:0 0 22px;
  display:flex;align-items:center;gap:13px;color:var(--accent-2);
  padding-bottom:12px;border-bottom:2px dashed var(--line);font-weight:700;
}
section.card h2 .idx{
  font-family:'JetBrains Mono',monospace;font-size:14px;color:#fff;
  background:var(--accent-2);border-radius:7px;padding:5px 9px;font-weight:700;
  flex-shrink:0;
}
section.card h2 .actions{
  margin-left:auto;display:flex;gap:6px;
}
.h2-btn{
  width:32px;height:32px;border-radius:7px;border:1px solid var(--line);
  background:var(--paper);color:var(--ink-soft);cursor:pointer;
  display:flex;align-items:center;justify-content:center;font-size:12px;
  transition:all .15s;
}
.h2-btn:hover{color:var(--accent);border-color:var(--accent);transform:translateY(-1px);}
.h2-btn.is-bookmarked{color:var(--accent);border-color:var(--accent);background:var(--accent-soft);}

section.card h3{
  font-size:19px;font-weight:700;margin:28px 0 14px;color:var(--accent);
  background:var(--accent-soft);display:inline-block;padding:6px 14px;border-radius:6px;
}
section.card h3:first-of-type{margin-top:4px;}
section.card h4.subhead{
  font-family:'Poppins',sans-serif;font-size:14px;font-weight:700;
  text-transform:uppercase;letter-spacing:.5px;color:var(--ink);
  margin:22px 0 11px;display:flex;align-items:center;gap:10px;
  border-left:4px solid var(--accent);padding-left:10px;
}

section.card p{
  margin:0 0 16px;color:var(--ink-soft);
  text-align:justify;font-size:16px;line-height:var(--rhythm);
}
section.card ul,section.card ol{margin:10px 0 22px;padding-left:0;list-style:none;}
section.card ul li,section.card ol li{
  position:relative;margin-bottom:12px;padding-left:26px;
  text-align:justify;font-size:16px;line-height:1.7;color:var(--ink-soft);
}
section.card ul li::before{
  content:"▪";color:var(--accent-2);font-size:1.2rem;
  position:absolute;left:6px;top:-2px;
}
section.card ol{counter-reset:item;}
section.card ol li::before{
  counter-increment:item;content:counter(item)".";
  position:absolute;left:0;top:0;font-weight:700;color:var(--accent);
  font-family:'JetBrains Mono',monospace;font-size:15px;
}
section.card li strong{color:var(--ink);font-weight:700;}

section.card ul.sub-list{margin:8px 0 12px;padding-left:0;}
section.card ul.sub-list li{padding-left:22px;font-size:15px;margin-bottom:8px;}
section.card li>ul.sub-list{margin-left:24px;}
section.card ul.sub-list li::before{
  content:"–";color:var(--ink-faint);font-size:1rem;left:4px;top:-1px;
}

/* stamp badge */
.stamp{
  display:inline-flex;align-items:center;gap:6px;
  font-family:'JetBrains Mono',monospace;font-size:10.5px;font-weight:700;
  color:var(--accent);border:2px dashed var(--accent);border-radius:5px;
  padding:3px 8px;transform:rotate(-2deg);letter-spacing:.5px;
  margin:2px 4px 2px 0;white-space:nowrap;
  background:color-mix(in srgb,var(--accent-soft) 50%,transparent);
}
.stamp i{font-size:10px;}

table.data{
  width:100%;border-collapse:collapse;margin:16px 0 20px;
  font-size:14.5px;border-radius:8px;overflow:hidden;
  border:1px solid var(--line);
}
table.data th{
  background:var(--paper-2);font-family:'Poppins',sans-serif;font-size:12px;
  text-transform:uppercase;letter-spacing:.5px;color:var(--ink-soft);
  text-align:left;padding:11px 14px;border-bottom:2px solid var(--accent);
}
table.data td{padding:13px 14px;border-bottom:1px solid var(--line-soft);vertical-align:top;color:var(--ink-soft);}
table.data tr:last-child td{border-bottom:none;}
table.data tr:hover td{background:color-mix(in srgb,var(--accent-soft) 30%,transparent);}

/* note box */
.note-box{
  background:linear-gradient(135deg,color-mix(in srgb,var(--accent-soft) 60%,var(--card)) 0%,color-mix(in srgb,var(--accent-soft) 90%,var(--card)) 100%);
  border:1px solid color-mix(in srgb,var(--accent) 30%,var(--line));
  border-left:5px solid var(--accent);
  border-radius:9px;padding:18px 22px;margin:24px 0;
  box-shadow:0 3px 10px color-mix(in srgb,var(--accent) 8%,transparent);
  position:relative;
}
.note-box::before{
  content:"";position:absolute;left:-1px;top:-1px;bottom:-1px;width:5px;
  background:var(--accent);border-radius:9px 0 0 9px;
}
.note-box b{
  color:var(--accent);display:flex;align-items:center;gap:8px;margin-bottom:8px;
  font-family:'Poppins',sans-serif;font-size:14px;font-weight:700;text-transform:uppercase;letter-spacing:.5px;
}
.note-box b i{font-size:13px;}
.note-box ul{margin:8px 0 0;}

/* highlights */
mark.hl{
  background:var(--hl-yellow);color:inherit;padding:1px 3px;border-radius:3px;
  box-decoration-break:clone;-webkit-box-decoration-break:clone;
  cursor:pointer;transition:background .15s;
}
mark.hl.hl-green{background:var(--hl-green);}
mark.hl.hl-pink{background:var(--hl-pink);}
mark.hl.hl-blue{background:var(--hl-blue);}
mark.hl.user-highlight{
  padding:0 .08em;border-radius:2px;cursor:pointer;
  box-decoration-break:clone;-webkit-box-decoration-break:clone;
}

/* horizontally scroll wide study tables without clipping the page */
.table-scroll{
  width:100%;overflow-x:auto;overscroll-behavior-inline:contain;
  -webkit-overflow-scrolling:touch;margin:16px 0 20px;border-radius:8px;
}
.table-scroll table.data{margin:0;}

/* complete row + section nav */
.complete-row{
  display:flex;align-items:center;justify-content:space-between;
  gap:14px;margin-top:30px;padding-top:18px;border-top:1px dashed var(--line);
  flex-wrap:wrap;
}
.complete-btn{
  display:inline-flex;align-items:center;gap:10px;
  border:1.5px solid var(--line);background:var(--paper);color:var(--ink-soft);
  font-weight:600;font-size:14px;padding:9px 16px;border-radius:99px;cursor:pointer;
  transition:all .2s;font-family:'Hind',sans-serif;
}
.complete-btn .box{
  width:18px;height:18px;border-radius:5px;border:2px solid var(--ink-soft);
  display:flex;align-items:center;justify-content:center;font-size:11px;color:transparent;
  transition:all .2s;
}
.complete-btn:hover{border-color:var(--success);color:var(--ink);}
.complete-btn.done{
  border-color:var(--success);color:var(--success);
  background:color-mix(in srgb,var(--success) 10%,var(--card));
}
.complete-btn.done .box{background:var(--success);border-color:var(--success);color:#fff;}
.section-meta{
  font-family:'JetBrains Mono',monospace;font-size:12px;color:var(--ink-faint);
  display:flex;align-items:center;gap:10px;
}
.section-meta .time{display:flex;align-items:center;gap:5px;}

/* prev / next nav */
.section-nav{
  display:flex;justify-content:space-between;gap:12px;margin-top:30px;
}
.nav-btn{
  flex:1;display:flex;flex-direction:column;gap:4px;
  padding:14px 16px;border:1px solid var(--line);border-radius:10px;
  background:var(--paper);color:var(--ink-soft);text-decoration:none;
  cursor:pointer;transition:all .2s;min-width:0;
}
.nav-btn:hover{border-color:var(--accent);background:var(--card);transform:translateY(-1px);box-shadow:var(--shadow);}
.nav-btn .nav-label{font-family:'JetBrains Mono',monospace;font-size:10px;color:var(--ink-faint);text-transform:uppercase;letter-spacing:1px;}
.nav-btn .nav-title{font-size:14px;font-weight:600;color:var(--ink);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;}
.nav-btn.next{align-items:flex-end;text-align:right;}
.nav-btn.prev .nav-label::before{content:"← ";}
.nav-btn.next .nav-label::after{content:" →";}
.nav-btn.disabled{opacity:.4;pointer-events:none;}

/* highlight toolbar */
#hl-toolbar{
  position:fixed;z-index:80;display:none;
  background:var(--ink);color:var(--paper);
  padding:5px;border-radius:9px;
  box-shadow:0 8px 24px rgba(0,0,0,.3);gap:3px;
}
#hl-toolbar button{
  background:transparent;border:none;color:inherit;padding:7px 9px;
  border-radius:6px;cursor:pointer;font-size:13px;
  display:flex;align-items:center;gap:6px;
  font-family:'Hind',sans-serif;font-weight:600;
}
#hl-toolbar button:hover{background:rgba(255,255,255,.15);}
#hl-toolbar .swatch{
  width:14px;height:14px;border-radius:3px;border:1px solid rgba(255,255,255,.3);display:inline-block;
}
#hl-toolbar .divider{width:1px;background:rgba(255,255,255,.2);margin:4px 2px;}

/* ---------- 160-question PCS-pattern exam quiz ---------- */
.exam-quiz-overlay{
  position:fixed;inset:0;z-index:9000;display:none;
  align-items:center;justify-content:center;padding:20px;
  background:rgba(9,15,23,.74);backdrop-filter:blur(6px);
}
.exam-quiz-overlay.open{display:flex;}
.exam-quiz-dialog{
  width:min(760px,100%);max-height:min(880px,calc(100vh - 40px));
  display:flex;flex-direction:column;overflow:hidden;
  background:var(--card);border:1px solid var(--line);border-radius:18px;
  box-shadow:0 24px 80px rgba(0,0,0,.35);
}
.exam-quiz-head{padding:20px 24px 16px;border-bottom:1px solid var(--line);background:var(--paper-2);}
.exam-quiz-title-row{display:flex;align-items:flex-start;justify-content:space-between;gap:18px;}
.exam-quiz-title-row h2{margin:0;font-size:23px;line-height:1.3;}
.exam-quiz-title-row p{margin:4px 0 0;color:var(--ink-soft);font-size:13px;line-height:1.5;}
.exam-quiz-close{
  width:38px;height:38px;flex:0 0 38px;border:1px solid var(--line);border-radius:9px;
  background:var(--card);color:var(--ink);cursor:pointer;font-size:17px;
}
.exam-quiz-close:hover{border-color:var(--accent);color:var(--accent);}
.exam-quiz-meter{display:flex;align-items:center;gap:12px;margin-top:16px;}
.exam-quiz-track{height:8px;flex:1;background:var(--card);border:1px solid var(--line);border-radius:99px;overflow:hidden;}
.exam-quiz-fill{height:100%;width:0;background:linear-gradient(90deg,var(--accent-2),var(--accent));transition:width .25s ease;}
.exam-quiz-counter{font-family:'JetBrains Mono',monospace;font-size:12px;font-weight:700;color:var(--ink-soft);white-space:nowrap;}
.exam-quiz-body{padding:26px 28px;overflow-y:auto;overscroll-behavior:contain;}
.exam-quiz-kicker{
  display:inline-flex;align-items:center;gap:7px;margin-bottom:12px;
  color:var(--accent-2);font-family:'JetBrains Mono',monospace;font-size:11px;font-weight:700;
  text-transform:uppercase;letter-spacing:.7px;
}
.exam-setup{text-align:center;padding:4px 0 8px;}
.exam-setup-icon{
  width:66px;height:66px;margin:0 auto 14px;border-radius:18px;display:grid;place-items:center;
  background:color-mix(in srgb,var(--accent-2) 13%,var(--card));color:var(--accent-2);font-size:28px;
}
.exam-setup h3{margin:0 0 7px;font-size:24px;}
.exam-setup > p{margin:0 auto 20px;max-width:580px;color:var(--ink-soft);line-height:1.6;}
.exam-count-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;margin:0 auto 18px;}
.exam-count-option{
  padding:16px 8px;border:1.5px solid var(--line);border-radius:11px;background:var(--card);
  color:var(--ink);font-family:'Hind',sans-serif;cursor:pointer;transition:.15s ease;
}
.exam-count-option:hover{border-color:var(--accent-2);transform:translateY(-1px);}
.exam-count-option strong{display:block;font-family:'Poppins',sans-serif;font-size:23px;line-height:1.1;}
.exam-count-option span{display:block;margin-top:4px;color:var(--ink-soft);font-size:12px;}
.exam-count-option.active{border-color:var(--accent-2);background:color-mix(in srgb,var(--accent-2) 11%,var(--card));box-shadow:0 0 0 2px color-mix(in srgb,var(--accent-2) 13%,transparent);}
.exam-setup-note{padding:12px 14px;border-radius:9px;background:var(--paper-2);color:var(--ink-soft);font-size:13px;line-height:1.55;text-align:left;}
.exam-question{font-size:22px;line-height:1.55;margin:0 0 22px;color:var(--ink);}
.exam-options{display:grid;gap:11px;}
.exam-option{
  width:100%;display:flex;align-items:flex-start;gap:12px;text-align:left;
  padding:14px 16px;border:1.5px solid var(--line);border-radius:11px;
  background:var(--card);color:var(--ink);font-family:'Hind',sans-serif;font-size:16px;
  line-height:1.5;cursor:pointer;transition:border-color .15s,background .15s,transform .15s;
}
.exam-option:hover:not(:disabled){border-color:var(--accent-2);transform:translateY(-1px);background:var(--paper-2);}
.exam-option:focus-visible{outline:3px solid color-mix(in srgb,var(--accent-2) 35%,transparent);outline-offset:2px;}
.exam-option:disabled{cursor:default;opacity:1;}
.exam-letter{
  display:grid;place-items:center;flex:0 0 30px;height:30px;border-radius:8px;
  background:var(--paper-2);border:1px solid var(--line);font-family:'JetBrains Mono',monospace;
  font-size:12px;font-weight:700;
}
.exam-option.correct{border-color:var(--success);background:color-mix(in srgb,var(--success) 12%,var(--card));}
.exam-option.correct .exam-letter{background:var(--success);border-color:var(--success);color:#fff;}
.exam-option.wrong{border-color:var(--danger);background:color-mix(in srgb,var(--danger) 10%,var(--card));}
.exam-option.wrong .exam-letter{background:var(--danger);border-color:var(--danger);color:#fff;}
.exam-feedback{
  margin-top:18px;padding:13px 15px;border-radius:10px;border-left:4px solid var(--accent-2);
  background:var(--paper-2);color:var(--ink-soft);font-size:14px;line-height:1.65;
}
.exam-feedback strong{color:var(--ink);}
.exam-quiz-foot{
  display:flex;align-items:center;justify-content:space-between;gap:12px;
  padding:16px 24px;border-top:1px solid var(--line);background:var(--paper-2);
}
.exam-nav-btn{
  border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:9px;
  padding:10px 16px;font-family:'Hind',sans-serif;font-size:14px;font-weight:700;cursor:pointer;
}
.exam-nav-btn.primary{background:var(--accent-2);border-color:var(--accent-2);color:#fff;min-width:132px;}
.exam-nav-btn:hover:not(:disabled){filter:brightness(.96);transform:translateY(-1px);}
.exam-nav-btn:disabled{opacity:.42;cursor:not-allowed;}
.exam-score-card{text-align:center;padding:4px 0 18px;}
.exam-score-ring{
  width:150px;height:150px;margin:6px auto 18px;border-radius:50%;display:grid;place-items:center;
  background:conic-gradient(var(--accent-2) var(--score-angle),var(--paper-2) 0);
  position:relative;
}
.exam-score-ring::before{content:'';position:absolute;inset:12px;background:var(--card);border-radius:50%;}
.exam-score-number{position:relative;z-index:1;font-family:'Poppins',sans-serif;font-size:30px;font-weight:800;line-height:1.15;}
.exam-score-number small{display:block;font-family:'Hind',sans-serif;font-size:13px;color:var(--ink-soft);font-weight:600;}
.exam-score-card h3{font-size:24px;margin:0 0 6px;}
.exam-score-card p{margin:0;color:var(--ink-soft);}
.exam-breakdown{display:grid;grid-template-columns:repeat(5,1fr);gap:8px;margin:20px 0;}
.exam-breakdown div{padding:10px 6px;border:1px solid var(--line);border-radius:9px;background:var(--paper-2);text-align:center;}
.exam-breakdown strong{display:block;font-family:'JetBrains Mono',monospace;font-size:15px;}
.exam-breakdown span{display:block;font-size:11px;line-height:1.35;color:var(--ink-soft);}
.exam-review{margin-top:18px;text-align:left;}
.exam-review h4{margin:0 0 10px;font-size:16px;}
.exam-review-item{padding:11px 13px;border:1px solid var(--line);border-radius:9px;margin-bottom:8px;font-size:13px;line-height:1.55;}
.exam-review-item b{color:var(--danger);}
.exam-review-item span{color:var(--success);font-weight:700;}
@media(max-width:620px){
  .exam-quiz-overlay{padding:0;align-items:stretch;}
  .exam-quiz-dialog{max-height:none;height:100%;border-radius:0;border:0;}
  .exam-quiz-head{padding:16px 17px 13px;}
  .exam-quiz-body{padding:21px 17px;}
  .exam-question{font-size:19px;}
  .exam-quiz-foot{padding:13px 16px;}
  .exam-breakdown{grid-template-columns:repeat(2,1fr);}
  .exam-count-grid{grid-template-columns:repeat(2,1fr);}
}

/* floating action buttons */
.fab-stack{
  position:fixed;right:24px;bottom:24px;z-index:30;
  display:flex;flex-direction:column;gap:10px;
}
.fab{
  width:44px;height:44px;border-radius:50%;border:1px solid var(--line);
  background:var(--card);color:var(--ink-soft);cursor:pointer;
  display:flex;align-items:center;justify-content:center;font-size:15px;
  box-shadow:var(--shadow-lg);transition:all .2s;
}
.fab:hover{transform:translateY(-2px);color:var(--accent);border-color:var(--accent);}
.fab.hidden{opacity:0;pointer-events:none;transform:scale(.5);}
@media(max-width:780px){.fab-stack{right:16px;bottom:16px;}}

/* ---------- inline river map figure ---------- */
figure.river-map{
  margin:22px 0 10px;border:1px solid var(--line);border-radius:12px;
  overflow:hidden;background:#fdfcf6;box-shadow:var(--shadow);
}
figure.river-map img{
  display:block;width:100%;max-height:520px;object-fit:contain;
  background:#fdfcf6;padding:10px;
}
figure.river-map figcaption{
  display:flex;align-items:flex-start;gap:9px;
  padding:11px 16px;font-size:13px;line-height:1.55;
  color:var(--ink-soft);background:var(--paper-2);
  border-top:1px solid var(--line);margin:0;text-align:left;
}
figure.river-map figcaption i{color:var(--accent-2);margin-top:2px;flex-shrink:0;}
figure.river-map figcaption .img-credit{color:var(--ink-faint);font-size:11.5px;font-style:italic;white-space:nowrap;}
@media(max-width:560px){
  figure.river-map img{max-height:320px;padding:6px;}
}
@media print{
  figure.river-map{box-shadow:none;border:1px solid #999;}
}
/* smaller inline map variant */
figure.river-map.map-small{max-width:420px;margin-left:auto;margin-right:auto;}
figure.river-map.map-small img{max-height:260px;}
@media(max-width:560px){
  figure.river-map.map-small{max-width:100%;}
  figure.river-map.map-small img{max-height:220px;}
}

/* ---------- river page-break divider (within merged rivers section) ---------- */
.river-break{
  position:relative;display:flex;align-items:center;justify-content:center;
  margin:36px 0 30px;border-top:2px dashed var(--line);
}
.river-break span{
  position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);
  display:inline-flex;align-items:center;gap:7px;
  background:var(--card);padding:5px 16px;border:1px solid var(--line);border-radius:99px;
  color:var(--ink-faint);font-size:12.5px;font-family:'Hind',sans-serif;white-space:nowrap;
}
.river-break span i{color:var(--accent-2);}
@media print{
  .river-break{page-break-before:always;border-top:none;margin:0;height:0;overflow:hidden;}
  .river-break span{display:none;}
}

.menu-toggle{display:none;}

footer.reader-footer{
  text-align:center;color:var(--ink-faint);font-size:12px;
  margin-top:40px;font-family:'JetBrains Mono',monospace;line-height:1.8;
}
footer.reader-footer .kbd-hint{
  display:flex;flex-wrap:wrap;justify-content:center;gap:6px;margin-top:14px;
}
footer.reader-footer kbd{
  font-family:'JetBrains Mono',monospace;font-size:10px;
  background:var(--card);border:1px solid var(--line);border-radius:4px;
  padding:2px 6px;color:var(--ink-soft);
}

/* responsive */
@media(max-width:900px){
  .app{grid-template-columns:1fr;}
  .sidebar{
    position:fixed;left:0;top:44px;bottom:0;width:280px;z-index:60;
    transform:translateX(-100%);box-shadow:var(--shadow-lg);
  }
  .sidebar.open{transform:translateX(0);}
  .menu-toggle{display:flex;}
  main{padding:28px 16px 110px;}
  section.card{padding:24px 18px 22px;}
}

@media(max-width:620px){
  section.card p,section.card ul li,section.card ol li,.hero p{text-align:start;}
  section.card h2{font-size:21px;line-height:1.35;gap:9px;align-items:flex-start;}
  section.card h2 .idx{font-size:12px;padding:4px 7px;margin-top:2px;}
  section.card h2 .actions{flex-shrink:0;}
  section.card h3{font-size:17px;line-height:1.45;}
  .table-scroll table.data{min-width:620px;}
}

button:focus-visible,a:focus-visible,select:focus-visible,input:focus-visible{
  outline:3px solid color-mix(in srgb,var(--accent-2) 45%,transparent);
  outline-offset:2px;
}

::selection{background:color-mix(in srgb,var(--accent-2) 40%,transparent);}

/* print */
@media print{
  .progress-shell,.sidebar,.fab-stack,#hl-toolbar,.section-nav,.complete-row,.h2-btn,.menu-toggle,#sidebar-scrim{display:none !important;}
  .app{grid-template-columns:1fr;}
  main{padding:0;}
  body{background:#fff;color:#000;font-size:12pt;line-height:1.6;}
  section.card{box-shadow:none;border:1px solid #999;page-break-inside:avoid;margin-bottom:14px;padding:14px 18px;}
  section.card h2{font-size:18pt;}
  section.card h3{font-size:13pt;background:#eee;}
  .stamp{color:#000;border-color:#000;background:#fff3a3;}
  mark.hl{background:#fff3a3 !important;}
  .note-box{background:#fff8e1 !important;border:1px solid #999;}
  .hero h1{font-size:22pt;}
  table.data{font-size:10pt;}
  table.data th{background:#eee !important;-webkit-print-color-adjust:exact;print-color-adjust:exact;}
}

@media (prefers-reduced-motion: reduce){
  *{animation-duration:.001s !important;transition-duration:.001s !important;}
  html{scroll-behavior:auto;}
}

/* ---------- IMAGE LIGHTBOX ---------- */
section.card img{cursor:zoom-in;}
#img-lightbox{
  position:fixed;
  inset:0;
  background:#000;
  display:none;
  align-items:center;
  justify-content:center;
  z-index:9999;
}
#img-lightbox.open{display:flex;}
#img-lightbox img{
  max-width:100vw;
  max-height:100vh;
  width:auto;
  height:auto;
  object-fit:contain;
  display:block;
  margin:0;
  padding:0;
  border:none;
  box-shadow:none;
  border-radius:0;
}
#img-lightbox-close{
  position:fixed;
  top:16px;
  left:16px;
  width:44px;
  height:44px;
  border:none;
  border-radius:50%;
  background:rgba(255,255,255,.12);
  color:#fff;
  font-size:22px;
  line-height:1;
  display:flex;
  align-items:center;
  justify-content:center;
  cursor:pointer;
  z-index:10000;
}
#img-lightbox-close:hover{background:rgba(255,255,255,.22);}