/* ============================================================
   LA BÀN CƠ THỂ — BỘ SÁCH ĐỌC NGƯỜI
   Hệ thống thiết kế dùng chung cho năm quyển.

   Ý tưởng dàn trang: một cột đọc hẹp như sách giấy, lề trái dành
   cho ghi chú thực địa, số chương in lớn tràn ra lề, và mọi cảnh
   báo dùng màu đất chứ không dùng màu báo động.
   Sơ đồ vẽ bằng SVG nội tuyến, ăn theo biến màu nên tự đổi theo
   nền sáng/tối mà không cần hai bản hình.
   ============================================================ */

:root{
  --paper:#F2F3EF;
  --paper-2:#FBFBF8;
  --paper-3:#E9EBE4;
  --paper-4:#DFE2D9;
  --ink:#1B2127;
  --ink-soft:#4E5A62;
  --ink-faint:#7D8A90;
  --rule:#D3D7CD;
  --rule-soft:#E2E5DC;
  --accent:#2F6B63;
  --accent-ink:#20514B;
  --accent-soft:#E1EBE7;
  --warn:#8E4A22;
  --warn-soft:#F4E6DB;
  --warn-rule:#DEC2AA;
  --stop:#7A2E2E;
  --stop-soft:#F2E0DD;
  --cool:#3C5A7A;
  --cool-soft:#E2E9F1;
  --shadow:0 1px 2px rgba(27,33,39,.05), 0 8px 24px -16px rgba(27,33,39,.18);
  --f-display:"Fraunces","Playfair Display",Georgia,"Times New Roman",serif;
  --f-body:"Literata","Noto Serif",Georgia,serif;
  --f-ui:"Be Vietnam Pro","Segoe UI",system-ui,-apple-system,sans-serif;
  --f-mono:ui-monospace,"Cascadia Mono",Consolas,"Courier New",monospace;
  --col:44rem;
  padding-top:env(safe-area-inset-top,0px);
  padding-bottom:env(safe-area-inset-bottom,0px);
  color-scheme:light;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    --paper:#14181A; --paper-2:#1B2023; --paper-3:#232A2D; --paper-4:#2B3336;
    --ink:#E9EBE5; --ink-soft:#A8B4B4; --ink-faint:#7C8A8A;
    --rule:#2E3639; --rule-soft:#232A2D;
    --accent:#7FC4B6; --accent-ink:#A5D8CC; --accent-soft:#1A2F2C;
    --warn:#D99166; --warn-soft:#2E2219; --warn-rule:#4A3324;
    --stop:#D98A84; --stop-soft:#2E1E1D;
    --cool:#8FB3D9; --cool-soft:#1C2733;
    --shadow:0 1px 2px rgba(0,0,0,.4), 0 10px 30px -18px rgba(0,0,0,.7);
    color-scheme:dark;
  }
}
:root[data-theme="dark"]{
  --paper:#14181A; --paper-2:#1B2023; --paper-3:#232A2D; --paper-4:#2B3336;
  --ink:#E9EBE5; --ink-soft:#A8B4B4; --ink-faint:#7C8A8A;
  --rule:#2E3639; --rule-soft:#232A2D;
  --accent:#7FC4B6; --accent-ink:#A5D8CC; --accent-soft:#1A2F2C;
  --warn:#D99166; --warn-soft:#2E2219; --warn-rule:#4A3324;
  --stop:#D98A84; --stop-soft:#2E1E1D;
  --cool:#8FB3D9; --cool-soft:#1C2733;
  --shadow:0 1px 2px rgba(0,0,0,.4), 0 10px 30px -18px rgba(0,0,0,.7);
  color-scheme:dark;
}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--f-body);
  font-size:1.0625rem;
  line-height:1.72;
  font-synthesis-weight:none;
  text-rendering:optimizeLegibility;
}
img{max-width:100%;height:auto;display:block}
[hidden]{display:none!important}
::selection{background:var(--accent-soft);color:var(--ink)}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:2px}
@media (prefers-reduced-motion:reduce){*{animation-duration:.001ms!important;transition-duration:.001ms!important}}

/* ---------- khung trang ---------- */
.wrap{
  max-width:var(--col);
  margin-inline:auto;
  padding-left:max(18px,env(safe-area-inset-left,0px));
  padding-right:max(18px,env(safe-area-inset-right,0px));
}
.wide{max-width:66rem}

body::before{
  content:"";position:fixed;inset:0 0 auto;height:env(safe-area-inset-top,0px);
  z-index:40;background:var(--paper-2);
}
.topbar{
  position:sticky;top:env(safe-area-inset-top,0px);z-index:30;
  background:color-mix(in srgb,var(--paper-2) 92%,transparent);
  -webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);
  border-bottom:1px solid var(--rule);
}
.topbar-in{
  max-width:66rem;margin-inline:auto;
  padding-left:max(18px,env(safe-area-inset-left,0px));
  padding-right:max(18px,env(safe-area-inset-right,0px));
  padding-block:.55rem;
  display:flex;align-items:center;gap:.9rem;flex-wrap:wrap;
  font-family:var(--f-ui);font-size:.78rem;
}
.topbar a{color:var(--ink-soft);text-decoration:none}
.topbar a:hover{color:var(--accent-ink)}
.topbar .home{font-weight:600;color:var(--ink);letter-spacing:.01em}
.topbar .sep{color:var(--rule)}
.topbar .here{color:var(--ink-faint);min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.topbar .spacer{flex:1 1 auto}
#progress{position:absolute;left:0;bottom:-1px;height:2px;background:var(--accent);width:0}

/* ---------- chữ ---------- */
h1,h2,h3,h4{font-family:var(--f-display);font-weight:600;text-wrap:balance;line-height:1.18;margin:0}
h1{font-size:clamp(2rem,6.2vw,3.1rem);letter-spacing:-.015em}
h2{font-size:clamp(1.45rem,4vw,2rem);letter-spacing:-.01em;margin-top:3.4rem;margin-bottom:.9rem}
h3{font-size:clamp(1.14rem,2.8vw,1.35rem);margin-top:2.3rem;margin-bottom:.6rem}
h4{font-family:var(--f-ui);font-size:.84rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase;
   color:var(--accent-ink);margin-top:1.8rem;margin-bottom:.45rem}
p{margin:0 0 1.15rem}
a{color:var(--accent-ink);text-decoration-thickness:1px;text-underline-offset:.18em}
strong{font-weight:700}
em{font-style:italic}
.lede{font-size:1.19rem;line-height:1.62;color:var(--ink-soft);font-family:var(--f-body)}
.kicker{font-family:var(--f-ui);font-size:.75rem;font-weight:600;letter-spacing:.16em;text-transform:uppercase;color:var(--ink-faint);margin:0 0 .7rem}
.small{font-size:.92rem;color:var(--ink-soft)}
.center{text-align:center}
hr.div{border:0;border-top:1px solid var(--rule);margin:3rem 0}
hr.dots{border:0;height:1.4rem;margin:2.6rem 0;background:
  radial-gradient(circle,var(--rule) 1.4px,transparent 1.5px) center/1.1rem 1.4rem repeat-x}

ul,ol{margin:0 0 1.2rem;padding-left:1.35rem}
li{margin:0 0 .5rem}
li::marker{color:var(--ink-faint)}
ul.tight li,ol.tight li{margin-bottom:.22rem}
ul.plain{list-style:none;padding-left:0}
ul.check{list-style:none;padding-left:0}
ul.check li{position:relative;padding-left:1.7rem}
ul.check li::before{content:"";position:absolute;left:0;top:.52em;width:.78rem;height:.78rem;
  border:1.5px solid var(--rule);border-radius:2px}

/* ---------- mở chương ---------- */
.chap-open{padding-block:3.2rem 1.2rem;border-bottom:1px solid var(--rule);margin-bottom:2.2rem}
.chap-num{
  font-family:var(--f-display);font-size:clamp(3.4rem,13vw,6.4rem);line-height:.82;
  font-weight:600;color:var(--accent);opacity:.26;letter-spacing:-.04em;margin:0 0 .1rem;
}
.chap-open h1{margin-bottom:.9rem}
.chap-vol{font-family:var(--f-ui);font-size:.72rem;font-weight:700;letter-spacing:.15em;
  text-transform:uppercase;color:var(--ink-faint);margin:0 0 .9rem}

/* ---------- lề ghi chú ---------- */
.rail{
  font-family:var(--f-ui);font-size:.85rem;line-height:1.55;color:var(--ink-soft);
  border-left:2px solid var(--accent);padding-left:.9rem;margin:1.6rem 0;
}
.rail b{color:var(--ink);font-weight:600}
@media (min-width:1080px){
  .rail{
    float:left;clear:left;width:13rem;margin-left:-15.5rem;margin-top:.35rem;
    border-left:0;border-right:2px solid var(--accent);padding-left:0;padding-right:.9rem;text-align:right;
  }
}

/* ---------- khối nhấn ---------- */
.box{
  background:var(--paper-2);border:1px solid var(--rule);border-radius:3px;
  padding:1.15rem 1.25rem;margin:1.7rem 0;box-shadow:var(--shadow);
}
.box > :last-child{margin-bottom:0}
.box-t{font-family:var(--f-ui);font-size:.74rem;font-weight:700;letter-spacing:.11em;text-transform:uppercase;
  color:var(--ink-faint);margin:0 0 .55rem;display:flex;align-items:center;gap:.5rem}
.box-t::before{content:"";width:.5rem;height:.5rem;border-radius:50%;background:var(--ink-faint);flex:none}
.key{background:var(--accent-soft);border-color:color-mix(in srgb,var(--accent) 34%,transparent)}
.key .box-t{color:var(--accent-ink)}
.key .box-t::before{background:var(--accent)}
.warn{background:var(--warn-soft);border-color:var(--warn-rule)}
.warn .box-t{color:var(--warn)}
.warn .box-t::before{background:var(--warn);border-radius:1px;transform:rotate(45deg)}
.stop{background:var(--stop-soft);border-color:color-mix(in srgb,var(--stop) 36%,transparent)}
.stop .box-t{color:var(--stop)}
.stop .box-t::before{background:var(--stop);border-radius:1px}
.cool{background:var(--cool-soft);border-color:color-mix(in srgb,var(--cool) 32%,transparent)}
.cool .box-t{color:var(--cool)}
.cool .box-t::before{background:var(--cool)}

blockquote{
  margin:1.8rem 0;padding:.2rem 0 .2rem 1.3rem;border-left:3px solid var(--rule);
  font-family:var(--f-display);font-size:1.13rem;line-height:1.56;color:var(--ink);font-style:italic;
}
blockquote p{margin-bottom:.7rem}
blockquote > :last-child{margin-bottom:0}
blockquote cite{display:block;font-family:var(--f-ui);font-size:.8rem;font-style:normal;color:var(--ink-faint);margin-top:.5rem}

/* ---------- bảng ---------- */
.tw{overflow-x:auto;margin:1.7rem 0;border:1px solid var(--rule);border-radius:3px;background:var(--paper-2)}
table{border-collapse:collapse;width:100%;font-family:var(--f-ui);font-size:.88rem;line-height:1.5;min-width:30rem}
caption{caption-side:top;text-align:left;font-family:var(--f-ui);font-size:.78rem;font-weight:600;
  letter-spacing:.06em;text-transform:uppercase;color:var(--ink-faint);padding:.8rem 1rem .1rem}
th,td{padding:.6rem .8rem;text-align:left;vertical-align:top;border-bottom:1px solid var(--rule-soft)}
thead th{font-size:.74rem;font-weight:700;letter-spacing:.07em;text-transform:uppercase;color:var(--ink-faint);
  border-bottom:1px solid var(--rule);background:var(--paper-3);white-space:nowrap}
tbody tr:last-child td{border-bottom:0}
td.num,th.num{font-variant-numeric:tabular-nums;text-align:right;white-space:nowrap}
.t-hl{background:var(--accent-soft)}
.t-warn{background:var(--warn-soft)}
.t-stop{background:var(--stop-soft)}

/* ---------- hình ảnh ---------- */
figure{margin:2.2rem 0}
figure img{width:100%;border-radius:3px;background:var(--paper-3)}
figure.photo img{aspect-ratio:3/2;object-fit:cover}
figure.tall img{aspect-ratio:4/5;object-fit:cover}
figure.wide-img img{aspect-ratio:21/9;object-fit:cover}
figcaption{
  font-family:var(--f-ui);font-size:.83rem;line-height:1.55;color:var(--ink-soft);
  margin-top:.6rem;padding-left:.75rem;border-left:2px solid var(--accent);
}
figcaption b{color:var(--ink);font-weight:600}
.pair-img{display:grid;grid-template-columns:1fr 1fr;gap:.7rem}
.pair-img figure{margin:0}
.trio-img{display:grid;grid-template-columns:repeat(3,1fr);gap:.6rem;margin:2.2rem 0}
.trio-img figure{margin:0}
@media (max-width:30rem){.pair-img,.trio-img{grid-template-columns:1fr}}

/* ---------- sơ đồ ---------- */
figure.diagram{margin:2.4rem 0}
figure.diagram svg{width:100%;height:auto;display:block;overflow:visible}
.d-fill-paper{fill:var(--paper-2)}
.d-fill-page{fill:var(--paper)}
.d-fill-soft{fill:var(--accent-soft)}
.d-fill-warn{fill:var(--warn-soft)}
.d-fill-stop{fill:var(--stop-soft)}
.d-fill-cool{fill:var(--cool-soft)}
.d-fill-3{fill:var(--paper-3)}
.d-fill-a{fill:var(--accent)}
.d-fill-w{fill:var(--warn)}
.d-fill-s{fill:var(--stop)}
.d-fill-ink{fill:var(--ink)}
.d-fill-faint{fill:var(--ink-faint)}
.d-stroke{stroke:var(--rule);fill:none}
.d-stroke-2{stroke:var(--rule);fill:none;stroke-width:2}
.d-stroke-a{stroke:var(--accent);fill:none}
.d-stroke-a2{stroke:var(--accent);fill:none;stroke-width:2}
.d-stroke-w{stroke:var(--warn);fill:none}
.d-stroke-s{stroke:var(--stop);fill:none}
.d-stroke-c{stroke:var(--cool);fill:none}
.d-stroke-ink{stroke:var(--ink);fill:none}
.d-stroke-faint{stroke:var(--ink-faint);fill:none}
.d-dash{stroke-dasharray:5 4}
.d-dot{stroke-dasharray:2 3}
.d-t{fill:var(--ink);font-family:var(--f-ui);font-size:13px}
.d-t-s{fill:var(--ink-soft);font-family:var(--f-ui);font-size:11.5px}
.d-t-xs{fill:var(--ink-faint);font-family:var(--f-ui);font-size:10px;letter-spacing:.06em}
.d-t-a{fill:var(--accent-ink);font-family:var(--f-ui);font-size:12px;font-weight:600}
.d-t-b{fill:var(--ink);font-family:var(--f-ui);font-size:13px;font-weight:700}
.d-t-w{fill:var(--warn);font-family:var(--f-ui);font-size:11.5px;font-weight:600}
.d-t-st{fill:var(--stop);font-family:var(--f-ui);font-size:11.5px;font-weight:600}
.d-t-c{fill:var(--cool);font-family:var(--f-ui);font-size:11.5px;font-weight:600}
.d-t-num{fill:var(--accent);font-family:var(--f-display);font-size:26px;font-weight:600}
.d-t-big{fill:var(--ink);font-family:var(--f-display);font-size:20px;font-weight:600}

/* hình người vẽ trong sơ đồ */
.b-body{stroke:var(--ink-soft);fill:none;stroke-width:2.4;stroke-linecap:round;stroke-linejoin:round}
.b-body-a{stroke:var(--accent);fill:none;stroke-width:2.4;stroke-linecap:round;stroke-linejoin:round}
.b-body-w{stroke:var(--warn);fill:none;stroke-width:2.4;stroke-linecap:round;stroke-linejoin:round}
.b-head{fill:var(--paper-2);stroke:var(--ink-soft);stroke-width:2.4}
.b-head-a{fill:var(--accent-soft);stroke:var(--accent);stroke-width:2.4}
.b-head-w{fill:var(--warn-soft);stroke:var(--warn);stroke-width:2.4}
.b-ghost{stroke:var(--rule);fill:none;stroke-width:2;stroke-dasharray:4 4}

/* ---------- thang bậc ---------- */
.scale{list-style:none;padding:0;margin:1.8rem 0;counter-reset:s}
.scale li{
  counter-increment:s;position:relative;padding:.55rem 0 .55rem 3.1rem;
  border-top:1px solid var(--rule-soft);margin:0;
}
.scale li:first-child{border-top:1px solid var(--rule)}
.scale li:last-child{border-bottom:1px solid var(--rule)}
.scale li::before{
  content:counter(s);position:absolute;left:0;top:.5rem;
  width:1.9rem;height:1.9rem;border-radius:50%;
  display:grid;place-items:center;
  font-family:var(--f-ui);font-size:.8rem;font-weight:700;
  background:var(--accent-soft);color:var(--accent-ink);
}
.scale.zero{counter-reset:s -1}
.scale li b{display:block;font-family:var(--f-ui);font-size:.95rem}
.scale li span{color:var(--ink-soft);font-size:.96rem}
.scale li.danger::before{background:var(--warn-soft);color:var(--warn)}
.scale li.halt::before{background:var(--stop-soft);color:var(--stop)}

/* ---------- thẻ ---------- */
.cols2{display:grid;grid-template-columns:repeat(auto-fit,minmax(15rem,1fr));gap:1rem;margin:1.7rem 0}
.cols3{display:grid;grid-template-columns:repeat(auto-fit,minmax(11rem,1fr));gap:.8rem;margin:1.7rem 0}
.cols2 > *,.cols3 > *{min-width:0}
.card{background:var(--paper-2);border:1px solid var(--rule);border-radius:3px;padding:1rem 1.05rem}
.card h4{margin-top:0}
.card > :last-child{margin-bottom:0}
.card p{font-size:.97rem;margin-bottom:.7rem}
.card.on{background:var(--accent-soft);border-color:color-mix(in srgb,var(--accent) 32%,transparent)}
.card.off{background:var(--warn-soft);border-color:var(--warn-rule)}

/* ---------- mục lục ---------- */
.toc{list-style:none;padding:0;margin:2rem 0}
.toc li{margin:0;border-top:1px solid var(--rule-soft)}
.toc li:first-child{border-top:1px solid var(--rule)}
.toc li:last-child{border-bottom:1px solid var(--rule)}
.toc a{
  display:grid;grid-template-columns:2.6rem 1fr;gap:.2rem .9rem;
  padding:.95rem .2rem;text-decoration:none;color:inherit;align-items:baseline;
}
.toc a:hover{background:var(--paper-2)}
.toc a:hover .toc-h{color:var(--accent-ink)}
.toc .toc-n{font-family:var(--f-ui);font-size:.82rem;font-weight:700;color:var(--ink-faint);font-variant-numeric:tabular-nums}
.toc .toc-h{font-family:var(--f-display);font-size:1.1rem;font-weight:600;line-height:1.3}
.toc .toc-d{grid-column:2;font-family:var(--f-ui);font-size:.87rem;color:var(--ink-soft);line-height:1.5}
.toc .part{
  padding:1.6rem .2rem .5rem;font-family:var(--f-ui);font-size:.73rem;font-weight:700;
  letter-spacing:.14em;text-transform:uppercase;color:var(--accent-ink);
}
.toc li.part-row{border-top:0}

/* ---------- điều hướng ---------- */
.chapnav{
  display:flex;gap:.8rem;flex-wrap:wrap;justify-content:space-between;
  margin:3.6rem 0 3rem;padding-top:1.4rem;border-top:1px solid var(--rule);
}
.chapnav a{
  flex:1 1 13rem;min-width:0;text-decoration:none;color:inherit;
  background:var(--paper-2);border:1px solid var(--rule);border-radius:3px;padding:.8rem .95rem;
}
.chapnav a:hover{border-color:var(--accent)}
.chapnav .lbl{display:block;font-family:var(--f-ui);font-size:.7rem;font-weight:700;letter-spacing:.11em;
  text-transform:uppercase;color:var(--ink-faint);margin-bottom:.2rem}
.chapnav .ttl{font-family:var(--f-display);font-size:1rem;font-weight:600;line-height:1.3}
.chapnav .next{text-align:right}

/* ---------- bìa ---------- */
.cover{position:relative;border-bottom:1px solid var(--rule);overflow:hidden}
.cover-img{position:absolute;inset:0}
.cover-img img{width:100%;height:100%;object-fit:cover;filter:saturate(.55) contrast(1.02)}
.cover-img::after{
  content:"";position:absolute;inset:0;
  background:linear-gradient(185deg,color-mix(in srgb,var(--paper) 62%,transparent) 0%,
    color-mix(in srgb,var(--paper) 86%,transparent) 44%, var(--paper) 88%);
}
.cover-in{position:relative;padding-block:clamp(3.5rem,13vw,7rem) 2.6rem}
.cover h1{font-size:clamp(2.6rem,10.5vw,4.6rem);letter-spacing:-.025em;margin-bottom:1.1rem}
.cover .sub{font-family:var(--f-display);font-size:clamp(1.05rem,3.4vw,1.4rem);font-style:italic;
  color:var(--ink-soft);max-width:30ch;line-height:1.45;margin:0 0 1.6rem}
.cover .stamp{
  display:inline-flex;align-items:center;gap:.55rem;font-family:var(--f-ui);font-size:.74rem;font-weight:600;
  letter-spacing:.12em;text-transform:uppercase;color:var(--accent-ink);
  border:1px solid color-mix(in srgb,var(--accent) 45%,transparent);border-radius:999px;padding:.4rem .85rem;
  background:color-mix(in srgb,var(--accent-soft) 70%,transparent);
}

/* ---------- số liệu ---------- */
.stat-row{display:grid;grid-template-columns:repeat(auto-fit,minmax(9rem,1fr));gap:.8rem;margin:2rem 0}
.stat{border-top:2px solid var(--accent);padding-top:.6rem;min-width:0}
.stat .v{font-family:var(--f-display);font-size:clamp(1.7rem,5vw,2.3rem);font-weight:600;line-height:1;
  letter-spacing:-.02em;font-variant-numeric:tabular-nums}
.stat .k{font-family:var(--f-ui);font-size:.82rem;color:var(--ink-soft);line-height:1.45;margin-top:.35rem}

/* ---------- mã / phiếu ---------- */
pre{
  font-family:var(--f-mono);font-size:.82rem;line-height:1.6;
  background:var(--paper-2);border:1px solid var(--rule);border-radius:3px;
  padding:1rem 1.1rem;overflow-x:auto;margin:1.7rem 0;color:var(--ink-soft);
}
pre b{color:var(--ink);font-weight:700}
code{font-family:var(--f-mono);font-size:.9em;background:var(--paper-3);padding:.08em .32em;border-radius:2px}
pre code{background:none;padding:0;font-size:1em}

/* ---------- nhãn ---------- */
.tag{display:inline-block;font-family:var(--f-ui);font-size:.68rem;font-weight:700;letter-spacing:.09em;
  text-transform:uppercase;padding:.15rem .45rem;border-radius:2px;vertical-align:.1em;white-space:nowrap}
.tag-a{background:var(--accent-soft);color:var(--accent-ink)}
.tag-w{background:var(--warn-soft);color:var(--warn)}
.tag-s{background:var(--stop-soft);color:var(--stop)}
.tag-c{background:var(--cool-soft);color:var(--cool)}
.tag-n{background:var(--paper-3);color:var(--ink-faint)}

/* ---------- quyển sách ---------- */
.volgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(16rem,1fr));gap:1rem;margin:2.2rem 0}
.vol{
  display:block;text-decoration:none;color:inherit;
  border:1px solid var(--rule);border-radius:3px;background:var(--paper-2);
  padding:1.1rem 1.15rem;box-shadow:var(--shadow);
}
.vol:hover{border-color:var(--accent)}
.vol .vn{font-family:var(--f-ui);font-size:.7rem;font-weight:700;letter-spacing:.15em;
  text-transform:uppercase;color:var(--accent-ink);display:block;margin-bottom:.3rem}
.vol .vt{font-family:var(--f-display);font-size:1.25rem;font-weight:600;line-height:1.25;display:block;margin-bottom:.45rem}
.vol .vd{font-family:var(--f-ui);font-size:.88rem;color:var(--ink-soft);line-height:1.5;margin:0}
.vol .vmeta{font-family:var(--f-ui);font-size:.74rem;color:var(--ink-faint);margin-top:.6rem;
  padding-top:.55rem;border-top:1px solid var(--rule-soft)}

.volhead{padding-block:3rem 1.4rem;border-bottom:1px solid var(--rule);margin-bottom:2rem}
.volhead .vn{font-family:var(--f-ui);font-size:.74rem;font-weight:700;letter-spacing:.17em;
  text-transform:uppercase;color:var(--accent-ink);margin:0 0 .7rem}
.volhead h1{margin-bottom:.9rem}

/* ---------- bước ---------- */
.steps{list-style:none;padding:0;margin:1.8rem 0;counter-reset:st}
.steps > li{counter-increment:st;position:relative;padding:0 0 1.3rem 2.6rem;margin:0;
  border-left:1px solid var(--rule);margin-left:.9rem}
.steps > li:last-child{border-left-color:transparent;padding-bottom:0}
.steps > li::before{
  content:counter(st);position:absolute;left:-.9rem;top:0;
  width:1.8rem;height:1.8rem;border-radius:50%;display:grid;place-items:center;
  font-family:var(--f-ui);font-size:.78rem;font-weight:700;
  background:var(--accent);color:var(--paper-2);
}
.steps > li b{display:block;font-family:var(--f-ui);font-size:.97rem;margin-bottom:.15rem}
.steps > li p{margin-bottom:.5rem;font-size:.99rem}
.steps > li > :last-child{margin-bottom:0}

/* ---------- đối chiếu hai cột ---------- */
.vs{display:grid;grid-template-columns:1fr 1fr;gap:0;margin:1.8rem 0;
  border:1px solid var(--rule);border-radius:3px;overflow:hidden}
.vs > div{padding:1rem 1.05rem}
.vs > div:first-child{background:var(--accent-soft);border-right:1px solid var(--rule)}
.vs > div:last-child{background:var(--warn-soft)}
.vs h4{margin-top:0}
.vs > div:first-child h4{color:var(--accent-ink)}
.vs > div:last-child h4{color:var(--warn)}
.vs p,.vs li{font-family:var(--f-ui);font-size:.92rem;line-height:1.55}
.vs > div > :last-child{margin-bottom:0}
@media (max-width:30rem){.vs{grid-template-columns:1fr}.vs > div:first-child{border-right:0;border-bottom:1px solid var(--rule)}}

/* ---------- dải cường độ ---------- */
.meter{margin:1.6rem 0}
.meter .mrow{display:grid;grid-template-columns:7.5rem 1fr 2.6rem;gap:.6rem;align-items:center;
  font-family:var(--f-ui);font-size:.85rem;margin-bottom:.45rem}
.meter .mlab{color:var(--ink-soft);text-align:right}
.meter .mbar{height:.62rem;border-radius:999px;background:var(--paper-3);overflow:hidden}
.meter .mbar i{display:block;height:100%;background:var(--accent);border-radius:999px}
.meter .mbar.w i{background:var(--warn)}
.meter .mbar.s i{background:var(--stop)}
.meter .mval{font-variant-numeric:tabular-nums;color:var(--ink);font-weight:600}
@media (max-width:30rem){.meter .mrow{grid-template-columns:5.2rem 1fr 2.4rem;font-size:.76rem}}

/* ---------- bài tập ---------- */
.drill{border:1px dashed var(--rule);border-radius:3px;padding:1rem 1.15rem;margin:1.8rem 0;background:var(--paper-2)}
.drill .box-t{color:var(--accent-ink)}
.drill .box-t::before{background:var(--accent);border-radius:1px;transform:rotate(45deg)}
.drill > :last-child{margin-bottom:0}

footer.bookfoot{
  border-top:1px solid var(--rule);margin-top:3rem;padding-block:2rem 3rem;
  font-family:var(--f-ui);font-size:.82rem;color:var(--ink-faint);
}
footer.bookfoot p{margin-bottom:.6rem}

/* ============================================================
   BẢN IN — dùng khi nhà xuất bản in thử hoặc xuất PDF
   Luôn in trên nền giấy sáng, giữ nguyên màu của sơ đồ và khung,
   và không để một hình hay một bảng bị cắt làm đôi giữa hai trang.
   ============================================================ */
@media print{
  @page{size:A4;margin:18mm 16mm 20mm}
  @page:first{margin-top:0}

  :root,:root[data-theme="dark"],:root:not([data-theme="light"]){
    --paper:#fff; --paper-2:#fff; --paper-3:#F1F2EE; --paper-4:#E7E9E2;
    --ink:#101418; --ink-soft:#3C464D; --ink-faint:#6A757B;
    --rule:#C8CCC2; --rule-soft:#DFE2DA;
    --accent:#2B625B; --accent-ink:#1C4844; --accent-soft:#E6EFEB;
    --warn:#7E4120; --warn-soft:#F6EBE1; --warn-rule:#D9BEA6;
    --stop:#6C2A2A; --stop-soft:#F4E4E1;
    --cool:#35506D; --cool-soft:#E6EDF4;
    --shadow:none;
    color-scheme:light;
  }
  *{-webkit-print-color-adjust:exact!important;print-color-adjust:exact!important}

  body{background:#fff;font-size:10.5pt;line-height:1.58}
  .wrap{max-width:none;padding-left:0;padding-right:0}
  .topbar,#progress,.jump,.chapnav,body::before{display:none!important}

  /* mỗi chương và mỗi quyển bắt đầu ở trang mới */
  .sheet{break-before:page}
  .sheet:first-of-type{break-before:auto}
  .chap-open,.volhead{break-before:page;break-after:avoid}
  .cover{break-after:page}

  h1,h2,h3,h4{break-after:avoid;break-inside:avoid}
  h2{margin-top:1.6rem}
  p,li{orphans:3;widows:3}

  figure.diagram,figure.photo,figure.tall,figure.wide-img,.pair-img,.trio-img,
  .box,.drill,.rail,.vs,.card,.stat-row,.meter,blockquote{break-inside:avoid}
  figure.diagram svg{max-height:200mm}
  table{break-inside:auto}
  thead{display:table-header-group}
  tr,.steps > li,ul.check > li{break-inside:avoid}
  .tw{overflow:visible}

  a{color:inherit;text-decoration:none}
  .toc a{color:inherit}
  footer.bookfoot{break-inside:avoid;border-top:1px solid var(--rule)}
}