/* ─────────────────────────────────────────────
   DARK THEME (default)
───────────────────────────────────────────── */
:root {
  --nav-height: 118px;
  --bg:        #000000;
  --surface:   #0a0a0a;
  --surface2:  #111111;
  --border:    #333333;
  --accent:    #0070f3;
  --accent2:   #818cf8;
  --accent3:   #34d399;
  --accent4:   #fb7185;
  --text:      #ededed;
  --muted:     #888888;
  --h1:        #ffffff;
  --body-text: #c8d3dd;
  --list-text: #c8d3dd;
  --ex-p:      #aab8c8;
  --tip-p:     #fbbf24;
  --code-bg:   #111111;
  --code-text: #34d399;
  --ex-bg:     #000000;
  --nav-bg:    rgba(0,0,0,0.9);
  --hdr-g1:    #000000;
  --hdr-g2:    #0a0a0a;
  --td-alt:    rgba(255,255,255,0.03);
  --tip-bg:    rgba(251,191,36,0.08);
  --tip-bd:    rgba(251,191,36,0.2);
}

/* ─────────────────────────────────────────────
   LIGHT THEME
───────────────────────────────────────────── */
html.light {
  --bg:        #fafafa;
  --surface:   #ffffff;
  --surface2:  #f5f5f5;
  --border:    #eaeaea;
  --accent:    #0070f3;
  --accent2:   #4f46e5;
  --accent3:   #0d9488;
  --accent4:   #e11d48;
  --text:      #111111;
  --muted:     #666666;
  --h1:        #000000;
  --body-text: #1f1f1f;
  --list-text: #1f1f1f;
  --ex-p:      #3a3a3a;
  --tip-p:     #92400e;
  --code-bg:   #f5f5f5;
  --code-text: #0070f3;
  --ex-bg:     #fafafa;
  --nav-bg:    rgba(250,250,250,0.9);
  --hdr-g1:    #fafafa;
  --hdr-g2:    #ffffff;
  --td-alt:    rgba(0,0,0,0.02);
  --tip-bg:    rgba(245,158,11,0.06);
  --tip-bd:    rgba(245,158,11,0.18);
}

/* ─────────────────────────────────────────────
   RESET & BASE
───────────────────────────────────────────── */
*,*::before,*::after { box-sizing:border-box; margin:0; padding:0; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Sora', sans-serif;
  font-weight: 400;
  line-height: 1.72;
  min-height: 100vh;
  transition: background .25s, color .25s;
}

/* ─────────────────────────────────────────────
   HEADER
───────────────────────────────────────────── */
header {
  background: linear-gradient(140deg, var(--hdr-g1) 0%, var(--hdr-g2) 55%, var(--hdr-g1) 100%);
  border-bottom: 1px solid var(--border);
  padding: 1.4rem 2rem 1rem;
  position: relative;
  overflow: hidden;
}
header::before {
  content:'';
  position:absolute; inset:0;
  background:
    radial-gradient(ellipse 55% 90% at 85% 40%, rgba(245,158,11,.08) 0%, transparent 65%),
    radial-gradient(ellipse 40% 60% at 8% 85%,  rgba(56,189,248,.06) 0%, transparent 60%);
  pointer-events:none;
}
.hdr-inner {
  max-width:1400px; margin:auto; position:relative;
  display:flex; align-items:center; justify-content:space-between; gap:2rem;
}
.hdr-text { flex:1; }
.hdr-logo {
  flex-shrink:0;
  filter: drop-shadow(0 4px 16px rgba(255,153,0,0.3));
}
@media (max-width: 599px) { .hdr-logo { display:none; } }

.exam-badge {
  display:inline-block;
  font-family:'JetBrains Mono',monospace;
  font-size:0.88rem; letter-spacing:.14em; text-transform:uppercase;
  color:var(--accent); border:1px solid var(--accent);
  padding:.22rem .7rem; border-radius:3px; margin-bottom:1rem;
}

header h1 {
  font-family:'Sora',sans-serif;
  font-size: clamp(1.4rem,3vw,2.2rem);
  font-weight:800;
  color: var(--h1);
  line-height:1.12;
  margin-bottom:.4rem;
}
header h1 em { font-style:normal; color:var(--accent); }

.hdr-meta {
  display:flex; gap:1.2rem; flex-wrap:wrap; margin-top:.6rem;
  font-family:'JetBrains Mono',monospace; font-size:0.88rem; color:var(--muted);
}
.hdr-meta strong { color:var(--accent2); }

/* ─────────────────────────────────────────────
   STICKY NAV
───────────────────────────────────────────── */
nav {
  position:sticky; top:0; z-index:200;
  background:var(--nav-bg);
  backdrop-filter:blur(12px);
  border-bottom:1px solid var(--border);
}
.nav-inner {
  max-width:1400px; margin:auto; padding:0 1.5rem;
  display:flex; align-items:stretch; gap:0; flex-wrap:nowrap;
  overflow-x:auto;
}
.nav-inner::-webkit-scrollbar { height:2px; }
.nav-inner::-webkit-scrollbar-thumb { background:var(--border); }

.nav-sep { font-family:'JetBrains Mono',monospace; font-size:0.81rem;
  letter-spacing:.1em; text-transform:uppercase; color:var(--muted);
  padding:.75rem .6rem; white-space:nowrap; align-self:center; }

.nav-inner a {
  font-family:'Sora',sans-serif; font-weight:500; font-size:0.98rem;
  color:var(--muted); text-decoration:none;
  padding:.75rem .75rem;
  border-bottom:2px solid transparent;
  white-space:nowrap;
  transition: color .18s, border-color .18s;
}
.nav-inner a:hover, .nav-inner a.active { color:var(--accent); border-bottom-color:var(--accent); }
.nav-inner a.dom-link { font-weight:600; }
.nav-inner a.dom-link:hover { color:var(--accent2); border-bottom-color:var(--accent2); }

/* theme toggle */
.theme-toggle {
  margin-left:auto; flex-shrink:0;
  display:flex; align-items:center; gap:.5rem;
  background:var(--surface2); border:1px solid var(--border);
  border-radius:20px; padding:.22rem .32rem .22rem .7rem;
  cursor:pointer; font-family:'JetBrains Mono',monospace;
  font-size:0.81rem; color:var(--muted); white-space:nowrap;
  user-select:none; align-self:center; margin-top:0;
  transition:border-color .2s, color .2s;
}
.theme-toggle:hover { border-color:var(--accent); color:var(--accent); }
.tog-track {
  width:30px; height:17px; background:var(--border); border-radius:9px;
  position:relative; transition:background .25s; flex-shrink:0;
}
html.light .tog-track { background:var(--accent); }
.tog-thumb {
  position:absolute; top:2.5px; left:2.5px;
  width:12px; height:12px; border-radius:50%;
  background:#fff; box-shadow:0 1px 3px rgba(0,0,0,.35);
  transition:transform .22s;
}
html.light .tog-thumb { transform:translateX(13px); }

/* ─── Domain tab strip (row 2 of nav) ─── */
.nav-domains {
  display:flex; gap:.4rem; padding:.4rem 1.5rem;
  border-top:1px solid var(--border);
  overflow-x:auto; scrollbar-width:none;
}
.nav-domains::-webkit-scrollbar { display:none; }
.nav-domains .dtab {
  font-size:0.82rem; padding:.22rem .75rem;
  white-space:nowrap; flex-shrink:0;
}
.nav-domains .dtab small { opacity:.65; margin-left:.3rem; font-size:0.75rem; }

/* ─── Task subtask strip (row 3 of nav) ─── */
.nav-subtasks {
  border-top:1px solid var(--border);
  background:var(--surface2);
}
.dtasks { display:none; }
.dtasks.active {
  display:flex; flex-direction:row; gap:.2rem;
  max-width:1400px; margin:0 auto; padding:.28rem 1.5rem;
  overflow-x:auto; scrollbar-width:none;
}
.dtasks.active::-webkit-scrollbar { display:none; }
.nav-subtasks .tlink {
  font-size:0.84rem; white-space:nowrap; flex-shrink:0;
  padding:.2rem .55rem; border-left:none; border-radius:3px;
  transition:color .18s, background .18s;
}
.nav-subtasks .tlink:hover { color:var(--accent); background:rgba(0,112,243,.08); border-left-color:transparent; }

/* ─── Progress strip (bottom of nav) ─── */
.nav-progress {
  height:3px; background:var(--surface2);
  border-top:1px solid var(--border);
}
.nav-progress .progress-fill { height:100%; border-radius:0; }

/* ─────────────────────────────────────────────
   MAIN LAYOUT
───────────────────────────────────────────── */
main { max-width:1400px; margin:auto; padding:2rem 1.5rem 5rem; display:flex; gap:2rem; align-items:flex-start; }
@media (max-width: 899px) {
  main { flex-direction:column; padding:1.5rem 1rem 4rem; }
}
.content-wrapper { flex:1; min-width:0; max-width:1100px; }

/* ─────────────────────────────────────────────
   DOMAIN TABS (nav-integrated; pill style)
───────────────────────────────────────────── */
.dtab {
  font-family:'JetBrains Mono',monospace; font-size:0.9rem; letter-spacing:.04em;
  padding:.4rem 1rem; border-radius:4px;
  border:1px solid var(--border); color:var(--muted); background:var(--surface);
  cursor:pointer; transition:all .18s; user-select:none;
}
.dtab:hover { color:var(--accent); border-color:var(--accent); }
.dtab.active {
  color:var(--accent); border-color:var(--accent);
  background:rgba(0,112,243,.08);
}

/* ─────────────────────────────────────────────
   PROGRESS BAR (lives in nav-progress strip)
───────────────────────────────────────────── */
.progress-fill {
  height:100%;
  background:linear-gradient(90deg,var(--accent),var(--accent2));
  transition: width .4s ease;
}

/* ─────────────────────────────────────────────
   DOMAIN SECTION (shown/hidden)
───────────────────────────────────────────── */
.domain-section { display:none; }
.domain-section.active { display:block; }

/* ─────────────────────────────────────────────
   DOMAIN INTRO
───────────────────────────────────────────── */
.domain-intro {
  background:var(--surface); border:1px solid var(--border);
  border-left:4px solid var(--accent); border-radius:8px;
  padding:1.1rem 1.5rem; margin-bottom:1.4rem;
}
.domain-intro h2 {
  font-family:'Sora',sans-serif; font-size:1.02rem; font-weight:600;
  color:var(--accent); text-transform:uppercase; letter-spacing:.1em; margin-bottom:.45rem;
}
.domain-intro p { color:var(--muted); font-size:1.1rem; }
.wt-badge {
  display:inline-block; margin-top:.7rem;
  font-family:'JetBrains Mono',monospace; font-size:0.9rem;
  background:rgba(245,158,11,.1); color:var(--accent);
  padding:.18rem .55rem; border-radius:3px; border:1px solid rgba(245,158,11,.28);
}

/* ─────────────────────────────────────────────
   TASK SECTION
───────────────────────────────────────────── */
.task-section { margin-bottom:0; padding-bottom:1.8rem; }
.task-section + .task-section {
  border-top: 2px solid var(--border);
  padding-top: 1.8rem;
}
.task-header {
  display:flex; align-items:flex-start; gap:1rem;
  margin-bottom:1.2rem; padding-bottom:0.8rem;
  border-bottom:1px solid var(--border);
}
.task-badge {
  font-family:'JetBrains Mono',monospace; font-size:0.85rem; font-weight:500;
  background:var(--accent); color:#080c14;
  padding:.26rem .6rem; border-radius:3px; white-space:nowrap; margin-top:.22rem;
  flex-shrink:0;
}
.task-title h2 {
  font-family:'Sora',sans-serif; font-size:clamp(1.15rem, 4vw, 1.56rem); font-weight:700; color:var(--h1);
}
.task-title p { color:var(--muted); font-size:1.04rem; margin-top:.3rem; }

/* ─────────────────────────────────────────────
   CONCEPT CARDS
───────────────────────────────────────────── */
.card {
  background:var(--surface); border:1px solid var(--border);
  border-radius:10px; margin-bottom:1.3rem; overflow:hidden;
  transition:border-color .18s;
}
.card:hover { border-color:var(--accent2); }

.card-hdr {
  display:flex; align-items:center; gap:.7rem;
  padding:.9rem 1.4rem;
  background:var(--surface2);
  cursor:pointer; user-select:none;
}
.card-icon { font-size:1.44rem; flex-shrink:0; }
.card-title {
  font-family:'Sora',sans-serif; font-weight:600; font-size:1.21rem;
  color:var(--h1); flex:1;
}
.tags { display:flex; gap:.35rem; flex-wrap:wrap; }
.tag {
  font-family:'JetBrains Mono',monospace; font-size:0.75rem; letter-spacing:.04em;
  padding:.12rem .45rem; border-radius:3px; text-transform:uppercase;
}
.ti { background:rgba(245,158,11,.11); color:var(--accent);   border:1px solid rgba(245,158,11,.24); }
.tn { background:rgba(56,189,248,.09); color:var(--accent2);  border:1px solid rgba(56,189,248,.2);  }
.td { background:rgba(52,211,153,.09); color:var(--accent3);  border:1px solid rgba(52,211,153,.2);  }
.te { background:rgba(248,113,113,.09);color:var(--accent4);  border:1px solid rgba(248,113,113,.2); }
.tc { background:rgba(167,139,250,.09);color:#a78bfa;         border:1px solid rgba(167,139,250,.2); }

.chev { color:var(--muted); font-size:1.0rem; transition:transform .22s; flex-shrink:0; }
.card.open .chev { transform:rotate(180deg); }

.card-body { display:none; padding:.2rem 1.4rem 1.4rem; }
.card.open .card-body { display:block; }

/* ─────────────────────────────────────────────
   BODY COMPONENTS
───────────────────────────────────────────── */
.sec-lbl {
  font-family:'JetBrains Mono',monospace; font-size:0.81rem;
  letter-spacing:.15em; text-transform:uppercase;
  color:var(--accent2); margin:1.2rem 0 .55rem;
  display:flex; align-items:center; gap:.5rem;
}
.sec-lbl::after { content:''; flex:1; height:1px; background:var(--border); }

p.bt { font-size:1.1rem; color:var(--body-text); margin-bottom:.7rem; }

ul.bl { list-style:none; padding:0; margin-bottom:.7rem; }
ul.bl li {
  font-size:1.07rem; color:var(--list-text);
  padding:.28rem 0 .28rem 1.15rem; position:relative;
}
ul.bl li::before {
  content:'▸'; position:absolute; left:0;
  color:var(--accent); font-size:0.85rem; top:.38rem;
}

/* example box */
.ex {
  background:var(--ex-bg); border:1px solid var(--border);
  border-left:3px solid var(--accent3); border-radius:6px;
  padding:.9rem 1.15rem; margin:.7rem 0;
}
.ex .xl {
  font-family:'JetBrains Mono',monospace; font-size:0.78rem; letter-spacing:.12em;
  text-transform:uppercase; color:var(--accent3); margin-bottom:.42rem;
}
.ex p { font-size:1.05rem; color:var(--ex-p); }

/* exam tip */
.tip {
  background:var(--tip-bg); border:1px solid var(--tip-bd);
  border-radius:6px; padding:.82rem 1.05rem; margin:.7rem 0;
  display:flex; gap:.7rem; align-items:flex-start;
}
.tip-ico { font-size:1.31rem; flex-shrink:0; }
.tip p { font-size:1.05rem; color:var(--tip-p); }
.tip strong { color:var(--accent4); }

/* exam trap */
.trap {
  background:rgba(167,139,250,0.07); border:1px solid rgba(167,139,250,0.28);
  border-left:3px solid #a78bfa;
  border-radius:6px; padding:.82rem 1.05rem; margin:.7rem 0;
  display:flex; gap:.7rem; align-items:flex-start;
}
html.light .trap {
  background:rgba(124,58,237,0.06); border-color:rgba(124,58,237,0.25);
  border-left-color:#7c3aed;
}
.trap-ico { font-size:1.31rem; flex-shrink:0; }
.trap p { font-size:1.05rem; color:#c4b5fd; }
html.light .trap p { color:#5b21b6; }
.trap strong { color:#a78bfa; }
html.light .trap strong { color:#6d28d9; }

/* table */
.tbl { width:100%; border-collapse:collapse; margin:.7rem 0; font-size:1.0rem; }
.tbl th {
  font-family:'JetBrains Mono',monospace; font-size:0.8rem; text-transform:uppercase;
  letter-spacing:.07em; background:var(--surface2); color:var(--accent2);
  padding:.55rem .85rem; text-align:left; border:1px solid var(--border);
}
.tbl td {
  padding:.5rem .85rem; border:1px solid var(--border);
  color:var(--ex-p); vertical-align:top;
}
.tbl tr:nth-child(even) td { background:var(--td-alt); }

/* code */
pre {
  background:var(--code-bg); border:1px solid var(--border); border-radius:6px;
  padding:.9rem 1.1rem; overflow-x:auto; margin:.7rem 0;
  font-family:'JetBrains Mono',monospace; font-size:0.94rem;
  color:var(--code-text); line-height:1.6;
}
.cm { color:var(--muted); }
.kw { color:var(--accent); }
.vl { color:var(--accent3); }

/* ─────────────────────────────────────────────
   FOOTER
───────────────────────────────────────────── */
footer {
  border-top:1px solid var(--border); padding:1.5rem 2rem;
  text-align:center;
  font-family:'JetBrains Mono',monospace; font-size:0.88rem; color:var(--muted);
}
footer span { display:block; margin-top:.3rem; color:var(--border); }


.task-details {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem 1.4rem;
  margin-top: 1rem;
}
.task-details strong {
  color: var(--accent2);
  font-family: 'JetBrains Mono', monospace;
  font-size:0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  display: block;
  margin: 0.8rem 0 0.4rem;
}
.task-details strong:first-child { margin-top: 0; }
.task-details ul {
  list-style: none;
  padding: 0;
  margin-bottom: 0;
}
.task-details ul li {
  font-size:1.02rem;
  color: var(--muted);
  padding: 0.2rem 0 0.2rem 1rem;
  position: relative;
}
.task-details ul li::before {
  content: '▹';
  position: absolute;
  left: 0;
  color: var(--accent);
  font-size:1.0rem;
}
html.light .task-details ul li::before { color: var(--accent); }


.tlink {
  font-family: 'Sora', sans-serif;
  font-size:0.94rem;
  color: var(--muted);
  text-decoration: none;
  padding: 0.2rem 0.5rem;
  border-left: 2px solid transparent;
  transition: all 0.2s;
}
.tlink:hover {
  color: var(--accent);
  border-left-color: var(--accent);
}
.dtasks { display: none; }
.dtasks.active { display: flex; flex-direction: column; gap: 0.3rem; margin: 0.3rem 0 0.8rem 1rem; }

/* ─────────────────────────────────────────────
   MNEMONICS, MCQs, & REFLECTIONS
───────────────────────────────────────────── */
.mnemonic {
  background: rgba(56, 189, 248, 0.08);
  border: 1px dashed var(--accent2);
  border-left: 4px solid var(--accent2);
  border-radius: 6px;
  padding: 0.8rem 1rem;
  margin: 1rem 0;
  display: flex;
  gap: 0.8rem;
  align-items: flex-start;
}
.mnemonic-ico { font-size:1.5rem; flex-shrink: 0; }
.mnemonic p { font-size:1.07rem; color: var(--body-text); margin: 0; }
.mnemonic strong { color: var(--accent2); }

.mcq-container {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.2rem 1.5rem;
  margin: 1.5rem 0;
}
.mcq-container h4 {
  font-family: 'JetBrains Mono', monospace;
  font-size:0.94rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.8rem;
}
.mcq-question {
  font-size:1.15rem;
  font-weight: 500;
  color: var(--h1);
  margin-bottom: 1rem;
}
.mcq-options {
  list-style: none;
  padding: 0;
  margin-bottom: 1rem;
}
.mcq-options li {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.6rem 1rem;
  margin-bottom: 0.5rem;
  font-size:1.06rem;
  color: var(--text);
  cursor: default;
}
.mcq-options li strong { color: var(--accent2); font-weight: 600; margin-right: 0.5rem; }
.mcq-answer {
  background: rgba(52, 211, 153, 0.08);
  border: 1px solid rgba(52, 211, 153, 0.2);
  border-radius: 6px;
  padding: 0.8rem 1rem;
  margin-top: 1rem;
  font-size:1.06rem;
  color: var(--body-text);
}
.mcq-answer strong { color: var(--accent3); }
.mcq-answer summary {
  font-weight: 600;
  color: var(--accent3);
  cursor: pointer;
  outline: none;
  user-select: none;
  margin-bottom: 0.5rem;
}

.domain-reflection {
  background: linear-gradient(135deg, var(--surface2) 0%, var(--surface) 100%);
  border: 1px solid var(--border);
  border-top: 4px solid var(--accent);
  border-radius: 8px;
  padding: 1.4rem 1.6rem;
  margin: 1.5rem 0;
}
.domain-reflection h3 {
  font-family: 'Sora', sans-serif;
  font-size:1.75rem;
  font-weight: 700;
  color: var(--h1);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.domain-reflection p, .domain-reflection li {
  font-size:1.12rem;
  color: var(--body-text);
}
.domain-reflection ul {
  margin-top: 1rem;
  padding-left: 1.2rem;
}
.domain-reflection li {
  margin-bottom: 0.5rem;
}

/* ─────────────────────────────────────────────
   KNOWLEDGE CHECK COLLAPSIBLE TOGGLE
───────────────────────────────────────────── */
.mcq-section-toggle {
  border-top: 2px solid var(--border);
  padding-top: 0.5rem;
}
.mcq-section-toggle > summary {
  font-family: 'Sora', sans-serif;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--h1);
  padding: 0.6rem 0;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  transition: color 0.2s;
}
.mcq-section-toggle > summary::-webkit-details-marker { display: none; }
.mcq-section-toggle > summary::after {
  content: '▾';
  font-size: 1.1rem;
  color: var(--muted);
  transition: transform 0.22s;
  flex-shrink: 0;
}
.mcq-section-toggle[open] > summary::after { transform: rotate(180deg); }
.mcq-section-toggle > summary:hover { color: var(--accent); }
.mcq-section-toggle[open] > summary {
  border-bottom: 1px solid var(--border);
  margin-bottom: 1.5rem;
  padding-bottom: 0.6rem;
}

/* ─────────────────────────────────────────────
   GUIDE IMAGES & LIGHTBOX
───────────────────────────────────────────── */
.guide-images {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem; margin: 1rem 0 0.5rem;
}
.guide-images figure { margin: 0; }
.guide-img {
  width: 100%; border-radius: 8px;
  border: 1px solid var(--border);
  display: block; cursor: zoom-in;
  transition: transform 0.2s, box-shadow 0.2s;
}
.guide-img:hover { transform: scale(1.012); box-shadow: 0 6px 24px rgba(0,0,0,0.45); }
.guide-img-cap {
  font-size: 0.73rem; color: var(--muted);
  text-align: center; margin-top: 0.3rem;
}
#img-lb {
  display: none; position: fixed; inset: 0;
  background: rgba(0,0,0,0.9); z-index: 9999;
  align-items: center; justify-content: center; cursor: zoom-out;
}
#img-lb.open { display: flex; }
#img-lb img {
  max-width: 92vw; max-height: 92vh;
  border-radius: 8px; box-shadow: 0 0 60px rgba(0,0,0,0.8);
}

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

/* ─────────────────────────────────────────────
   TOC SIDEBAR
───────────────────────────────────────────── */
.toc-sidebar {
  width: 210px;
  min-width: 210px;
  flex-shrink:0;
  position: sticky;
  top: calc(var(--nav-height) + 1rem);
  max-height: calc(100vh - var(--nav-height) - 2rem);
  overflow-y: auto;
  scrollbar-width: thin;
  display: none;
}
@media (min-width: 900px) {
  .toc-sidebar { display: block; }
}
.toc-inner h4 {
  font-family: var(--font-hdr, 'Sora', sans-serif);
  font-size: 0.95rem;
  color: var(--h1);
  margin-bottom: 1rem;
}
.toc-inner ul { list-style: none; padding: 0; }
.toc-inner li { margin-bottom: 0.6rem; }
.toc-inner a {
  font-family: var(--font-body, 'Sora', sans-serif);
  font-size: 0.85rem;
  color: var(--muted);
  text-decoration: none;
  transition: color 0.2s;
  display: block;
  line-height: 1.4;
  border-left: 2px solid transparent;
  padding-left: 0.8rem;
  margin-left: -0.8rem;
}
.toc-inner a:hover, .toc-inner a.active {
  color: var(--accent);
  border-left-color: var(--accent);
}

/* ─────────────────────────────────────────────
   CONTENT TOOLBAR
───────────────────────────────────────────── */
.content-toolbar {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
}
#globalSearch {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.6rem 1rem;
  border-radius: 6px;
  font-family: var(--font-body, 'Sora', sans-serif);
  font-size: 0.9rem;
  transition: border-color 0.2s;
}
#globalSearch:focus { outline: none; border-color: var(--accent2); }
#toggleAllCardsBtn {
  background: var(--surface2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.6rem 1rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--font-body, 'Sora', sans-serif);
  font-size: 0.85rem;
  transition: all 0.2s;
}
#toggleAllCardsBtn:hover { border-color: var(--accent); color: var(--accent); }

/* ─────────────────────────────────────────────
   QUIZ MODE & PROGRESS TRACKING
───────────────────────────────────────────── */
body.quiz-mode .task-section > .card { display: none !important; }
body.quiz-mode .task-header p, body.quiz-mode .task-details { display: none !important; }
body.quiz-mode .toc-sidebar { display: none !important; }

.progress-check {
  display: inline-flex;
  align-items: center;
  margin-right: 0.8rem;
  cursor: pointer;
}
.progress-check input {
  display: none;
}
.progress-check span {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-radius: 50%;
  display: inline-block;
  position: relative;
  transition: all 0.2s;
}
.progress-check input:checked + span {
  background-color: var(--accent);
  border-color: var(--accent);
}
.progress-check input:checked + span::after {
  content: "✓";
  position: absolute;
  color: white;
  font-size: 12px;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
#quizModeBtn {
  background: var(--accent);
  border: 1px solid var(--accent);
  color: #fff;
  padding: 0.6rem 1rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--font-body, 'Sora', sans-serif);
  font-size: 0.85rem;
  transition: all 0.2s;
  font-weight: 600;
}
#quizModeBtn:hover { filter: brightness(1.1); }


a { text-decoration: none !important; border-bottom: none !important; }

/* ─────────────────────────────────────────────
   SCROLL TO TOP BUTTON
───────────────────────────────────────────── */
#scrollTopBtn {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background-color: var(--accent);
  color: #fff;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all 0.3s ease;
  z-index: 9999;
}
#scrollTopBtn svg {
  width: 24px;
  height: 24px;
}
#scrollTopBtn.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
#scrollTopBtn:hover {
  filter: brightness(1.1);
  transform: translateY(-3px);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.3);
}

/* ─────────────────────────────────────────────
   MOBILE OPTIMIZATIONS (≤ 599px)
───────────────────────────────────────────── */
@media (max-width: 599px) {
  /* Tables: make wide tables scroll instead of overflowing the viewport */
  .tbl { display:block; overflow-x:auto; -webkit-overflow-scrolling:touch; }

  /* Content toolbar: stack search on its own row, buttons below */
  .content-toolbar { flex-wrap:wrap; }
  #globalSearch { min-width:100%; order:-1; }

  /* Scroll-to-top button: pull it away from the edge on small screens */
  #scrollTopBtn { right:16px; bottom:16px; width:42px; height:42px; }

  /* Nav: tighten up the 3 stacked rows to save vertical space */
  .nav-inner a { padding:.45rem .55rem; font-size:0.9rem; }
  .nav-sep { padding:.45rem .4rem; font-size:0.76rem; }
  .nav-domains { padding:.3rem 1rem; gap:.3rem; }
  .nav-domains .dtab { font-size:0.76rem; padding:.16rem .5rem; }
  .dtasks.active { padding:.22rem 1rem; }
  .nav-subtasks .tlink { font-size:0.8rem; padding:.16rem .45rem; }
}