/* ============================ TOKENS ============================ */
:root{
  --bg:#fbfbfa; --bg-2:#f4f3f0; --surface:#fff; --surface-2:#faf9f6;
  --border:#e7e5e0; --border-2:#d8d5cd;
  --text:#191814; --text-2:#4b4841; --text-3:#7d786d;
  --brand:#a8760a; --brand-2:#8a6108; --brand-bg:#fdf7e8; --brand-line:#ecdcae;
  --mob:#0f8a5f; --mob-bg:#eafaf3; --mob-line:#b9e6d3;
  --tip:#1a7f4b; --tip-bg:#eefaf2; --tip-line:#bfe6cf;
  --warn:#b4451f; --warn-bg:#fdf1ec; --warn-line:#f2cdbc;
  --info:#1f5f9e; --info-bg:#eef5fc; --info-line:#c3daf1;
  --sidebar:300px; --topbar:56px; --radius:12px;
  --shadow:0 1px 2px rgba(0,0,0,.05),0 8px 26px rgba(0,0,0,.06);
  --shadow-lg:0 12px 48px rgba(0,0,0,.16);
  --mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,monospace;
}
:root[data-theme="dark"]{
  --bg:#131209; --bg-2:#1a190f; --surface:#1c1b12; --surface-2:#232116;
  --border:#312e20; --border-2:#403c2a;
  --text:#f4f1e7; --text-2:#c8c3b3; --text-3:#8e897a;
  --brand:#e3ba52; --brand-2:#f0cc72; --brand-bg:#282214; --brand-line:#4b3f21;
  --mob:#4fd39b; --mob-bg:#12271d; --mob-line:#28503b;
  --tip:#5fcf92; --tip-bg:#14251b; --tip-line:#2a4a35;
  --warn:#f0906a; --warn-bg:#2a1a13; --warn-line:#553025;
  --info:#79b4ec; --info-bg:#141f2b; --info-line:#28405a;
  --shadow:0 1px 2px rgba(0,0,0,.4),0 8px 26px rgba(0,0,0,.35);
  --shadow-lg:0 12px 48px rgba(0,0,0,.6);
}
@media (prefers-color-scheme:dark){
  :root[data-theme="auto"]{
    --bg:#131209; --bg-2:#1a190f; --surface:#1c1b12; --surface-2:#232116;
    --border:#312e20; --border-2:#403c2a;
    --text:#f4f1e7; --text-2:#c8c3b3; --text-3:#8e897a;
    --brand:#e3ba52; --brand-2:#f0cc72; --brand-bg:#282214; --brand-line:#4b3f21;
    --mob:#4fd39b; --mob-bg:#12271d; --mob-line:#28503b;
    --tip:#5fcf92; --tip-bg:#14251b; --tip-line:#2a4a35;
    --warn:#f0906a; --warn-bg:#2a1a13; --warn-line:#553025;
    --info:#79b4ec; --info-bg:#141f2b; --info-line:#28405a;
    --shadow:0 1px 2px rgba(0,0,0,.4),0 8px 26px rgba(0,0,0,.35);
    --shadow-lg:0 12px 48px rgba(0,0,0,.6);
  }
}
/* ============================ BASE ============================ */
*{box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto} *{animation-duration:.01ms!important;transition-duration:.01ms!important}}
body{margin:0;background:var(--bg);color:var(--text);
  font:16px/1.68 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,system-ui,sans-serif;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
svg.ic{width:1em;height:1em;fill:none;stroke:currentColor;stroke-width:1.75;
  stroke-linecap:round;stroke-linejoin:round;flex:none;vertical-align:-.13em}
a{color:var(--brand-2)}
:focus-visible{outline:2px solid var(--brand);outline-offset:2px;border-radius:4px}
.skip{position:fixed;top:-60px;left:12px;z-index:200;background:var(--surface);
  border:1px solid var(--border-2);padding:9px 15px;border-radius:8px;
  text-decoration:none;color:var(--text);transition:top .15s}
.skip:focus{top:12px}
#progress{position:fixed;top:0;left:0;height:2px;width:0;z-index:60;
  background:linear-gradient(90deg,var(--brand),var(--brand-2))}

/* ============================ TOPBAR ============================ */
.topbar{position:fixed;top:0;left:0;right:0;height:var(--topbar);z-index:50;
  display:flex;align-items:center;gap:10px;padding:0 16px;
  background:color-mix(in srgb,var(--bg) 88%,transparent);
  backdrop-filter:saturate(180%) blur(12px);border-bottom:1px solid var(--border)}
.brand{display:flex;align-items:center;gap:9px;font-weight:700;letter-spacing:-.01em;
  text-decoration:none;color:var(--text);white-space:nowrap}
.brand .mark{width:26px;height:26px;border-radius:7px;display:grid;place-items:center;
  background:var(--brand);color:#fff;font-size:14px}
.brand .mark svg.ic{stroke-width:2.2}
.topbar .sp{flex:1}
.iconbtn{width:36px;height:36px;border-radius:9px;border:1px solid transparent;
  background:transparent;color:var(--text-2);display:grid;place-items:center;cursor:pointer;font-size:17px}
.iconbtn:hover{background:var(--bg-2);color:var(--text);border-color:var(--border)}
#menuBtn{display:none}
@media (max-width:1040px){#menuBtn{display:grid}}
@media (max-width:430px){.brand .sub2{display:none}}
.searchbtn{display:flex;align-items:center;gap:9px;height:36px;padding:0 10px 0 11px;
  border:1px solid var(--border-2);background:var(--surface);border-radius:9px;
  color:var(--text-3);cursor:pointer;font:inherit;font-size:14px;min-width:216px}
.searchbtn:hover{border-color:var(--brand-line);color:var(--text-2)}
.searchbtn .sp{flex:1;text-align:left}
kbd{font:600 11.5px/1 var(--mono);background:var(--bg-2);color:var(--text-3);
  border:1px solid var(--border-2);border-bottom-width:2px;border-radius:5px;padding:3px 5px;white-space:nowrap}
@media (max-width:760px){.searchbtn{min-width:0;width:36px;padding:0;justify-content:center}
  .searchbtn .sp,.searchbtn kbd{display:none}}

/* ============================ LAYOUT ============================ */
.shell{display:flex;padding-top:var(--topbar)}
.sidebar{width:var(--sidebar);flex:none;position:sticky;top:var(--topbar);
  height:calc(100vh - var(--topbar));overflow-y:auto;overscroll-behavior:contain;
  border-right:1px solid var(--border);padding:22px 12px 60px;scrollbar-width:thin}
.sidebar h2{font-size:11px;letter-spacing:.09em;text-transform:uppercase;color:var(--text-3);
  margin:22px 0 7px;padding:0 10px;font-weight:700;display:flex;align-items:center;gap:7px}
.sidebar h2:first-child{margin-top:0}
.sidebar h2 svg.ic{font-size:13px}
.sidebar h2.web{color:var(--brand-2)}
.sidebar h2.mobile{color:var(--mob)}
.sidebar a{display:flex;align-items:center;gap:10px;padding:7px 10px;border-radius:8px;
  color:var(--text-2);text-decoration:none;font-size:14.5px;line-height:1.35;border-left:2px solid transparent}
.sidebar a:hover{background:var(--bg-2);color:var(--text)}
.sidebar a[aria-current="true"]{background:var(--brand-bg);color:var(--brand-2);font-weight:600;border-left-color:var(--brand)}
.sidebar a[aria-current="true"].m{background:var(--mob-bg);color:var(--mob);border-left-color:var(--mob)}
.sidebar a .n{font:600 11.5px/1 var(--mono);color:var(--text-3);width:22px;flex:none}
.sidebar a[aria-current="true"] .n{color:inherit}
.content{flex:1;min-width:0;max-width:920px;margin:0 auto;padding:0 28px 100px}
.scrim{display:none}
@media (max-width:1040px){
  .sidebar{position:fixed;left:0;top:var(--topbar);z-index:45;background:var(--surface);
    transform:translateX(-100%);transition:transform .22s ease;box-shadow:var(--shadow-lg)}
  .sidebar.open{transform:none}
  .content{padding:0 20px 80px}
  .scrim{position:fixed;inset:var(--topbar) 0 0;background:rgba(0,0,0,.45);z-index:44}
  .scrim.on{display:block}
}
@media (max-width:560px){.content{padding:0 16px 70px}}

/* ============================ HERO ============================ */
.hero{padding:52px 0 34px;border-bottom:1px solid var(--border)}
.eyebrow{display:inline-flex;align-items:center;gap:7px;padding:5px 12px;border-radius:999px;
  background:var(--brand-bg);border:1px solid var(--brand-line);color:var(--brand-2);
  font-size:12.5px;font-weight:700;letter-spacing:.03em}
h1{font-size:clamp(30px,5vw,46px);line-height:1.1;letter-spacing:-.028em;margin:16px 0 12px;font-weight:750}
.lede{font-size:18.5px;line-height:1.6;color:var(--text-2);margin:0;max-width:62ch}
.meta{display:flex;flex-wrap:wrap;gap:8px;margin-top:22px}
.pill{display:inline-flex;align-items:center;gap:6px;font-size:13px;color:var(--text-3);
  background:var(--surface);border:1px solid var(--border);border-radius:999px;padding:5px 12px}

/* ============================ CARDS ============================ */
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(228px,1fr));gap:12px;margin:28px 0 8px}
.card{display:block;padding:16px 17px;border:1px solid var(--border);border-radius:var(--radius);
  background:var(--surface);text-decoration:none;color:inherit;transition:.16s}
.card:hover{border-color:var(--brand-line);background:var(--surface-2);transform:translateY(-2px);box-shadow:var(--shadow)}
.card.m:hover{border-color:var(--mob-line)}
.card .ci{width:34px;height:34px;border-radius:9px;display:grid;place-items:center;font-size:17px;
  background:var(--brand-bg);color:var(--brand-2);border:1px solid var(--brand-line);margin-bottom:11px}
.card.m .ci{background:var(--mob-bg);color:var(--mob);border-color:var(--mob-line)}
.card b{display:block;font-size:15.5px;font-weight:650;margin-bottom:3px;letter-spacing:-.005em}
.card span.d{display:block;font-size:13.5px;line-height:1.5;color:var(--text-3)}

/* ============================ SECTIONS ============================ */
.part{margin-top:64px;padding:20px 22px;border-radius:var(--radius);
  background:var(--brand-bg);border:1px solid var(--brand-line);
  scroll-margin-top:calc(var(--topbar) + 18px)}
.part.m{background:var(--mob-bg);border-color:var(--mob-line)}
.part h2{margin:0;font-size:22px;letter-spacing:-.02em;color:var(--brand-2);display:flex;align-items:center;gap:11px}
.part.m h2{color:var(--mob)}
.part p{margin:7px 0 0;font-size:15px;color:var(--text-2)}
section{padding-top:52px}
section+section{border-top:1px solid var(--border)}
h3.sec{font-size:25px;font-weight:700;letter-spacing:-.022em;margin:0 0 8px;
  scroll-margin-top:calc(var(--topbar) + 18px);display:flex;align-items:baseline;gap:12px}
h3.sec .num{font:700 13px/1 var(--mono);color:var(--brand);flex:none;
  border:1px solid var(--brand-line);background:var(--brand-bg);border-radius:6px;padding:5px 7px}
h3.sec.m .num{color:var(--mob);border-color:var(--mob-line);background:var(--mob-bg)}
h4{font-size:17px;font-weight:650;letter-spacing:-.01em;margin:32px 0 8px;
  scroll-margin-top:calc(var(--topbar) + 18px)}
.anchor{opacity:0;margin-left:8px;color:var(--text-3);text-decoration:none;font-size:.72em;transition:.15s}
h3.sec:hover .anchor,h4:hover .anchor,.anchor:focus{opacity:1}
p{margin:11px 0;color:var(--text-2)}
.sub{color:var(--text-3);font-size:15.5px;margin:0 0 20px}
ul{padding-left:21px;color:var(--text-2)}
li{margin:8px 0}
b,strong{color:var(--text);font-weight:650}
code{font:13.5px/1 var(--mono);background:var(--bg-2);border:1px solid var(--border);
  border-radius:5px;padding:2px 6px;color:var(--text)}

/* ============================ STEPS ============================ */
ol.steps{list-style:none;counter-reset:s;padding:0;margin:18px 0}
ol.steps>li{counter-increment:s;position:relative;padding:0 0 20px 44px;margin:0;color:var(--text-2)}
ol.steps>li::before{content:counter(s);position:absolute;left:0;top:-1px;width:27px;height:27px;
  border-radius:50%;background:var(--brand);color:#fff;font:700 13px/27px var(--mono);
  text-align:center;box-shadow:0 0 0 4px var(--bg)}
ol.steps.m>li::before{background:var(--mob)}
ol.steps>li::after{content:"";position:absolute;left:13px;top:29px;bottom:2px;width:2px;background:var(--border)}
ol.steps>li:last-child{padding-bottom:0}
ol.steps>li:last-child::after{display:none}
ol.steps li ul{margin:8px 0 0}

/* ============================ CALLOUTS ============================ */
.note{display:flex;gap:12px;padding:14px 16px;border-radius:var(--radius);margin:20px 0;
  border:1px solid var(--info-line);background:var(--info-bg)}
.note>svg.ic{font-size:19px;color:var(--info);margin-top:1px}
.note .bd{min-width:0}
.note .lbl{display:block;font-size:13.5px;font-weight:700;color:var(--info);margin-bottom:2px}
.note p{margin:0;font-size:15px;color:var(--text-2)}
.note p+p{margin-top:8px}
.note ul{margin:6px 0 0;font-size:15px}
.note.tip{border-color:var(--tip-line);background:var(--tip-bg)}
.note.tip>svg.ic,.note.tip .lbl{color:var(--tip)}
.note.warn{border-color:var(--warn-line);background:var(--warn-bg)}
.note.warn>svg.ic,.note.warn .lbl{color:var(--warn)}

/* ============================ FIGURES ============================ */
figure{margin:24px 0 8px}
.shot{position:relative;display:block;width:100%;padding:0;border:1px solid var(--border-2);
  border-radius:var(--radius);overflow:hidden;background:var(--surface);cursor:zoom-in;
  box-shadow:var(--shadow);transition:.16s}
.shot:hover{border-color:var(--brand-line);box-shadow:var(--shadow-lg)}
.shot img{display:block;width:100%}
.shot .zoom{position:absolute;right:10px;bottom:10px;width:32px;height:32px;border-radius:8px;
  display:grid;place-items:center;font-size:16px;color:#fff;background:rgba(20,18,12,.72);
  backdrop-filter:blur(6px);opacity:0;transition:.16s}
.shot:hover .zoom,.shot:focus-visible .zoom{opacity:1}
figcaption{font-size:13.5px;color:var(--text-3);margin-top:10px;text-align:center;line-height:1.5}
/* Ảnh điện thoại: dựng đứng, hẹp, xếp cạnh nhau khi có chỗ */
.phones{display:flex;gap:18px;flex-wrap:wrap;justify-content:center;margin:24px 0 8px}
.phones figure{margin:0;flex:0 1 260px;max-width:280px}
.phones .shot{border-radius:22px;border-width:6px;border-color:var(--border-2)}
.phones .shot .zoom{display:none}

/* ============================ TABLES ============================ */
.scroll{overflow-x:auto;margin:20px 0;border:1px solid var(--border);border-radius:var(--radius);background:var(--surface)}
table{width:100%;border-collapse:collapse;font-size:14.8px;min-width:460px}
th,td{text-align:left;padding:11px 15px;border-bottom:1px solid var(--border);vertical-align:top}
thead th{font-size:11.5px;text-transform:uppercase;letter-spacing:.06em;color:var(--text-3);
  font-weight:700;background:var(--surface-2);white-space:nowrap}
tbody tr:last-child td{border-bottom:0}
td{color:var(--text-2)}
.tag{display:inline-block;font-size:12.5px;font-weight:650;padding:2px 9px;border-radius:999px;
  background:var(--bg-2);border:1px solid var(--border-2);color:var(--text-2);white-space:nowrap}

/* ============================ TO TOP ============================ */
#toTop{position:fixed;right:20px;bottom:20px;width:42px;height:42px;border-radius:50%;
  border:1px solid var(--border-2);background:var(--surface);color:var(--text-2);
  display:grid;place-items:center;font-size:18px;cursor:pointer;box-shadow:var(--shadow);
  opacity:0;pointer-events:none;transition:.2s;z-index:40}
#toTop.on{opacity:1;pointer-events:auto}
#toTop:hover{color:var(--brand-2);border-color:var(--brand-line)}

/* ============================ SEARCH PALETTE ============================ */
.pal{position:fixed;inset:0;z-index:80;display:none;padding:12vh 16px 16px;
  background:rgba(18,16,10,.42);backdrop-filter:blur(3px)}
.pal.on{display:block}
.palbox{max-width:640px;margin:0 auto;background:var(--surface);border:1px solid var(--border-2);
  border-radius:15px;box-shadow:var(--shadow-lg);overflow:hidden}
.palin{display:flex;align-items:center;gap:11px;padding:14px 17px;border-bottom:1px solid var(--border)}
.palin svg.ic{font-size:18px;color:var(--text-3)}
.palin input{flex:1;border:0;background:transparent;font:inherit;font-size:16.5px;color:var(--text);outline:0}
.palin input::placeholder{color:var(--text-3)}
.palres{max-height:min(52vh,420px);overflow-y:auto;padding:7px}
.palres a{display:block;padding:10px 13px;border-radius:9px;text-decoration:none;color:inherit}
.palres a[data-sel="1"]{background:var(--brand-bg)}
.palres a b{display:block;font-size:14.8px;font-weight:600;color:var(--text)}
.palres a small{display:block;font-size:12.5px;color:var(--text-3);margin-top:2px;
  overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.palempty{padding:26px 16px;text-align:center;color:var(--text-3);font-size:14.5px}
.palfoot{display:flex;gap:16px;padding:9px 16px;border-top:1px solid var(--border);
  background:var(--surface-2);font-size:12px;color:var(--text-3)}
.palfoot span{display:flex;align-items:center;gap:5px}

/* ============================ LIGHTBOX ============================ */
.lb{position:fixed;inset:0;z-index:90;display:none;background:rgba(12,11,7,.93);padding:56px 20px 20px}
.lb.on{display:flex;flex-direction:column;align-items:center;justify-content:center}
.lb img{max-width:100%;max-height:calc(100vh - 130px);object-fit:contain;border-radius:8px;
  box-shadow:0 20px 70px rgba(0,0,0,.6)}
.lb .cap{color:#d9d4c6;margin-top:14px;font-size:14px;max-width:70ch;text-align:center}
.lb .nav{position:absolute;top:50%;transform:translateY(-50%);width:46px;height:46px;
  border-radius:50%;border:1px solid rgba(255,255,255,.22);background:rgba(255,255,255,.08);
  color:#fff;display:grid;place-items:center;font-size:20px;cursor:pointer;backdrop-filter:blur(6px)}
.lb .nav:hover{background:rgba(255,255,255,.18)}
.lb .prev{left:16px} .lb .next{right:16px}
.lb .close{position:absolute;top:14px;right:16px;width:40px;height:40px;border-radius:10px;
  border:1px solid rgba(255,255,255,.22);background:rgba(255,255,255,.08);color:#fff;
  display:grid;place-items:center;font-size:19px;cursor:pointer}
.lb .count{position:absolute;top:20px;left:20px;color:#a9a496;font:600 13px/1 var(--mono)}
@media (max-width:640px){.lb .nav{width:38px;height:38px}.lb .prev{left:6px}.lb .next{right:6px}}

footer{margin-top:60px;padding-top:24px;border-top:1px solid var(--border);color:var(--text-3);font-size:14px}

@media print{
  .topbar,.sidebar,#toTop,#progress,.pal,.lb,.scrim,.cards,.shot .zoom{display:none!important}
  .shell{padding-top:0}.content{max-width:none;padding:0}
  body{background:#fff;color:#000;font-size:11.5pt}
  section{padding-top:22px;break-inside:avoid}
  figure,.note,.scroll,.part{break-inside:avoid}
  .shot{box-shadow:none;border:1px solid #ccc}
  a{color:#000;text-decoration:none}
}


/* ===================== NHIỀU TRANG ===================== */
/* Không còn cuộn xuyên chương nên bỏ thanh tiến độ và vạch ngăn giữa section. */
section+section{border-top:0}
section:first-of-type{padding-top:34px}
.sidebar a[aria-current="page"]{background:var(--brand-bg);color:var(--brand-2);
  font-weight:600;border-left-color:var(--brand)}
.sidebar a[aria-current="page"].m{background:var(--mob-bg);color:var(--mob);border-left-color:var(--mob)}
.sidebar a[aria-current="page"] .n{color:inherit}

/* Điều hướng Trước / Tiếp — ở site nhiều trang thì đây là cách duy nhất đi
   tiếp mà không phải quay lại mục lục, khác hẳn bản một-trang-cuộn. */
.pager{display:flex;gap:12px;margin-top:48px;padding-top:24px;border-top:1px solid var(--border)}
.pager .gap{flex:1}
.pager a{flex:1;min-width:0;display:flex;align-items:center;gap:11px;padding:14px 16px;
  border:1px solid var(--border);border-radius:var(--radius);background:var(--surface);
  text-decoration:none;color:inherit;transition:.16s}
.pager a:hover{border-color:var(--brand-line);background:var(--surface-2);transform:translateY(-1px)}
.pager a.next{justify-content:flex-end;text-align:right}
.pager .tx{min-width:0}
.pager small{display:block;font-size:11.5px;text-transform:uppercase;letter-spacing:.06em;color:var(--text-3)}
.pager .tx span{display:block;font-size:14.5px;font-weight:600;color:var(--text);
  overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.pager svg.ic{font-size:18px;color:var(--text-3);flex:none}
@media (max-width:560px){.pager{flex-direction:column}.pager .gap{display:none}}

/* Mục lục đầy đủ ở trang chủ */
.toc{margin-top:40px}
.toc h2{font-size:13px;letter-spacing:.08em;text-transform:uppercase;color:var(--text-3);
  margin:30px 0 12px;font-weight:700;display:flex;align-items:center;gap:8px}
.toc h2.web{color:var(--brand-2)}
.toc h2.mobile{color:var(--mob)}
.toc ol{list-style:none;padding:0;margin:0;display:grid;
  grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:8px}
.toc a{display:flex;align-items:center;gap:12px;padding:12px 14px;border-radius:10px;
  border:1px solid var(--border);background:var(--surface);text-decoration:none;color:inherit;transition:.16s}
.toc a:hover{border-color:var(--brand-line);background:var(--surface-2);transform:translateY(-1px)}
.toc a .n{font:700 11.5px/1 var(--mono);color:var(--brand);flex:none;
  border:1px solid var(--brand-line);background:var(--brand-bg);border-radius:6px;padding:5px 6px}
.toc a.m .n{color:var(--mob);border-color:var(--mob-line);background:var(--mob-bg)}
.toc a span.t{font-size:14.5px;font-weight:600}
.toc a{align-items:flex-start}
.toc a .n{margin-top:1px}
.toc a .tx{display:flex;flex-direction:column;gap:3px;min-width:0}
.toc a span.d{font-size:12px;font-weight:400;color:var(--text-3);line-height:1.5}

/* Đường dẫn phân cấp trên mỗi trang chương */
.crumb{display:flex;align-items:center;gap:7px;font-size:13px;color:var(--text-3);
  margin:0 0 6px;padding-top:30px}
.crumb a{color:var(--text-3);text-decoration:none}
.crumb a:hover{color:var(--brand-2)}