:root {
  --purple-50:#EEEDFE;--purple-100:#CECBF6;--purple-400:#7F77DD;--purple-600:#534AB7;--purple-800:#3C3489;--purple-900:#26215C;
  --teal-50:#E1F5EE;--teal-100:#9FE1CB;--teal-400:#1D9E75;--teal-600:#0F6E56;--teal-800:#085041;--teal-900:#053D31;
  --coral-50:#FAECE7;--coral-100:#F5C4B3;--coral-400:#D85A30;--coral-600:#993C1D;--coral-800:#712B13;--coral-900:#4A1B0C;
  --gray-50:#F1EFE8;--gray-100:#D3D1C7;--gray-400:#888780;--gray-600:#5F5E5A;--gray-800:#444441;--gray-900:#2C2C2A;
  --blue-50:#E6F1FB;--blue-100:#B5D4F4;--blue-400:#378ADD;--blue-600:#185FA5;--blue-800:#0C447C;--blue-900:#073159;
  --amber-50:#FAEEDA;--amber-100:#FAC775;--amber-400:#BA7517;--amber-600:#854F0B;--amber-800:#633806;
  --ink:#11100f;--ink-soft:#4a4844;--ink-faint:#8c8a82;
  --paper:#fbfaf7;--paper-card:#ffffff;--line:#e7e3d8;
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;}
html{scroll-behavior:smooth;}
body{
  font-family:Georgia,'Times New Roman',serif;
  background:var(--paper);color:var(--ink);line-height:1.78;
  font-size:clamp(14px,1.6vw,15.5px);-webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none;}
.sans{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif;}

/* ── TOPNAV (điều hướng toàn site, 5 mục lõi) ── */
.topnav{
  position:sticky;top:0;z-index:1100;
  height:48px;background:#0f0e1c;
  display:flex;align-items:center;
  padding:0 clamp(14px,4vw,2rem);gap:0;
  border-bottom:1px solid rgba(127,119,221,.18);
  box-shadow:0 1px 0 rgba(0,0,0,.4);
  overflow-x:auto;
}
.topnav-brand{
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
  font-size:11.5px;font-weight:800;letter-spacing:.18em;
  text-transform:uppercase;color:#7F77DD;
  padding-right:1.4rem;margin-right:1rem;
  border-right:1px solid rgba(127,119,221,.25);
  white-space:nowrap;flex-shrink:0;
}
.topnav a{
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
  font-size:13px;font-weight:400;color:rgba(255,255,255,.48);
  text-decoration:none;padding:0 15px;height:48px;
  display:flex;align-items:center;white-space:nowrap;
  border-bottom:2px solid transparent;
  transition:color .14s,border-color .14s;
}
.topnav a:hover{color:rgba(255,255,255,.85);}
.topnav a.current{color:#fff;border-bottom-color:#7F77DD;font-weight:500;}

/* ── PROGRESS BAR ── */
#progressBar{
  position:fixed;top:48px;left:0;height:3px;width:0;z-index:1000;
  background:linear-gradient(90deg,var(--a600,#534AB7),var(--a400,#7F77DD));
  transition:width .08s linear;
}

/* ── TOPBAR (breadcrumb ngữ cảnh trang) ── */
.topbar{
  position:sticky;top:48px;z-index:500;
  background:var(--a900,var(--a800,#26215C));color:var(--a100,#CECBF6);
  padding:10px clamp(14px,4vw,24px);
  display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:6px;
  font-size:clamp(11px,2.5vw,13px);border-bottom:2px solid var(--a400,#7F77DD);
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.topbar-brand{font-weight:700;color:#fff;letter-spacing:.4px;display:flex;align-items:center;gap:9px;}
.topbar-dot{width:7px;height:7px;border-radius:50%;background:var(--a400,#7F77DD);flex-shrink:0;animation:blink 2.5s ease-in-out infinite;}
@keyframes blink{0%,100%{opacity:1}50%{opacity:.3}}
.topbar-nav{display:flex;gap:18px;flex-wrap:wrap;align-items:center;}
.topbar a{color:var(--a100,#CECBF6);font-weight:500;}
.topbar a:hover{color:#fff;text-decoration:underline;}
.topbar-sep{opacity:.35;}

/* ── HERO (hub & story) ── */
.hero{
  background:linear-gradient(135deg,var(--a900,var(--a800)) 0%,var(--a800) 50%,var(--a600) 100%);
  color:#fff;padding:clamp(36px,7vw,64px) clamp(16px,6vw,48px) clamp(28px,5vw,48px);
  text-align:center;position:relative;overflow:hidden;
}
.hero::before{
  content:"";position:absolute;inset:0;pointer-events:none;
  background:radial-gradient(circle at 18% 55%,rgba(255,255,255,.11) 0%,transparent 45%),
             radial-gradient(circle at 82% 18%,rgba(255,255,255,.07) 0%,transparent 38%);
}
.hero>*{position:relative;z-index:1;}
.hero-eyebrow{
  display:inline-flex;align-items:center;gap:8px;
  background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.25);
  border-radius:20px;padding:5px clamp(12px,3vw,16px);
  font-size:clamp(10px,2vw,11px);letter-spacing:1.2px;text-transform:uppercase;
  margin-bottom:clamp(12px,2.5vw,18px);color:var(--a100,#CECBF6);font-weight:600;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.eyebrow-dot{width:5px;height:5px;border-radius:50%;background:var(--a400,#7F77DD);animation:blink 2.5s ease-in-out infinite;}
.hero h1{
  font-family:Georgia,serif;font-size:clamp(26px,5vw,50px);font-weight:400;
  line-height:1.18;margin-bottom:clamp(10px,2vw,14px);color:#fff;
}
.hero-sub{
  font-size:clamp(13px,2.2vw,16px);color:var(--a100,#CECBF6);max-width:640px;
  margin:0 auto 20px;line-height:1.7;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.hero-hook{
  background:rgba(255,255,255,.09);border:1px solid rgba(255,255,255,.18);
  border-left:3px solid var(--a400,#7F77DD);border-radius:8px;
  padding:13px 20px;max-width:680px;margin:0 auto 20px;
  font-size:clamp(13px,2vw,15px);color:var(--a100,#CECBF6);
  line-height:1.7;font-style:italic;text-align:left;
}
.hero-pills{display:flex;justify-content:center;flex-wrap:wrap;gap:8px;margin-top:4px;}
.hero-pill{
  background:rgba(255,255,255,.10);border:1px solid rgba(255,255,255,.20);
  border-radius:100px;padding:4px 13px;font-size:11.5px;color:var(--a100,#CECBF6);
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.hero-pill strong{color:#fff;}

/* ── PAGE WRAP + LAYOUT ── */
.page-wrap{max-width:1180px;margin:0 auto;}
.layout{
  display:flex;align-items:flex-start;
  gap:clamp(16px,3vw,26px);
  padding:clamp(16px,3vw,28px) clamp(12px,3vw,20px);
}

/* ── SIDEBAR TOC ── */
.sidebar{
  width:220px;flex-shrink:0;
  position:sticky;top:108px;
  max-height:calc(100vh - 128px);overflow-y:auto;
}
.toc{
  background:var(--paper-card);border:1px solid var(--line);
  border-radius:12px;overflow:hidden;box-shadow:0 2px 10px rgba(0,0,0,.05);
}
.toc-head{
  background:var(--a900,var(--a800));color:var(--a100);
  padding:10px 15px;font-size:10px;font-weight:700;letter-spacing:1.3px;
  text-transform:uppercase;display:flex;align-items:center;gap:7px;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.toc-head::before{content:"▸";color:var(--a400,#7F77DD);}
.toc-list{list-style:none;padding:5px 0;}
.toc-list li a{
  display:flex;align-items:center;gap:9px;
  padding:7px 15px;font-size:12.5px;color:var(--ink);
  line-height:1.35;transition:all .13s;
  border-left:3px solid transparent;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.toc-list li a:hover{background:var(--a50,#EEEDFE);color:var(--a800);border-left-color:var(--a100);}
.toc-list li a.active{background:var(--a50,#EEEDFE);color:var(--a800);border-left-color:var(--a400);font-weight:600;}
.toc-badge{
  display:inline-flex;align-items:center;justify-content:center;
  min-width:20px;height:20px;border-radius:50%;
  background:var(--a400);color:#fff;font-size:9px;font-weight:700;flex-shrink:0;
}
.toc-list li a.active .toc-badge{background:var(--a600);}
.toc-back{padding:10px 15px;border-top:1px solid var(--line);font-size:12px;background:var(--paper);}
.toc-back a{color:var(--a600,#534AB7);font-weight:600;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;}
.toc-back a:hover{text-decoration:underline;}

/* ── MAIN CONTENT ── */
.main{flex:1;min-width:0;}

/* meta summary card */
.summary-card{
  background:linear-gradient(135deg,var(--a50,#EEEDFE) 0%,var(--paper) 80%);
  border:1px solid var(--a100,#CECBF6);border-left:4px solid var(--a400,#7F77DD);
  border-radius:12px;padding:clamp(16px,3.5vw,26px);margin-bottom:16px;
  box-shadow:0 2px 10px rgba(0,0,0,.04);
}
.summary-label{
  font-size:9.5px;letter-spacing:1.4px;text-transform:uppercase;
  color:var(--a600,#534AB7);font-weight:700;margin-bottom:10px;display:block;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.summary-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:8px;}
.summary-item{background:rgba(255,255,255,.6);border:1px solid var(--a100,#CECBF6);border-radius:8px;padding:10px 13px;}
.summary-k{font-size:9px;letter-spacing:1.2px;text-transform:uppercase;color:var(--a600,#534AB7);
  font-weight:700;margin-bottom:4px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;}
.summary-v{font-size:12.5px;color:var(--ink);line-height:1.5;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;}

/* chapter cards */
.card{
  background:var(--paper-card);border:1px solid var(--line);
  border-radius:12px;padding:clamp(18px,3.5vw,28px);
  margin-bottom:clamp(12px,2.5vw,16px);
  box-shadow:0 1px 5px rgba(0,0,0,.04);
  scroll-margin-top:72px;transition:box-shadow .2s;
}
.card:hover{box-shadow:0 4px 18px rgba(0,0,0,.09);}
.card.hook-card{border-color:var(--a100,#CECBF6);background:var(--a50,#EEEDFE);}
.card-num{
  display:inline-flex;align-items:center;justify-content:center;
  width:26px;height:26px;border-radius:50%;
  background:var(--a400,#7F77DD);color:#fff;
  font-size:10.5px;font-weight:700;margin-bottom:11px;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.card h2{
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
  font-size:clamp(15px,2.5vw,20px);font-weight:600;color:var(--ink);
  line-height:1.25;padding-bottom:9px;border-bottom:2px solid var(--line);margin-bottom:14px;
}
.card-bar{width:28px;height:3px;background:linear-gradient(90deg,var(--a600),var(--a400));border-radius:2px;margin-bottom:14px;}
.card p{margin-bottom:10px;font-size:clamp(14px,1.8vw,15.5px);color:var(--ink-soft);line-height:1.8;}
.card p:last-child{margin-bottom:0;}

/* callouts */
.callout{
  border-radius:8px;padding:13px 16px;margin-top:16px;
  font-size:13px;line-height:1.65;border-left:4px solid;
  display:flex;gap:10px;align-items:flex-start;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.callout-icon{font-size:14px;flex-shrink:0;margin-top:1px;}
.callout-body{flex:1;}
.callout-title{font-weight:700;font-size:9.5px;letter-spacing:.5px;text-transform:uppercase;margin-bottom:4px;}
.callout-mystery{background:var(--a50,#EEEDFE);border-color:var(--a400,#7F77DD);}
.callout-mystery .callout-title{color:var(--a800,#3C3489);}
.callout-check{background:var(--amber-50);border-color:var(--amber-400);}
.callout-check .callout-title{color:var(--amber-800);}

/* status pill */
.s-pill{
  display:inline-block;font-size:11px;font-weight:700;padding:3px 11px;
  border-radius:100px;letter-spacing:.3px;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.s-done{background:var(--teal-50);color:var(--teal-800);}
.s-outline{background:var(--amber-50);color:var(--amber-800);}

/* ── HUB STORY GRID ── */
.hub-section{padding:clamp(24px,4vw,40px) clamp(12px,4vw,24px);}
.hub-section-title{
  font-size:clamp(14px,2vw,16px);font-weight:700;color:var(--a800);
  margin-bottom:20px;display:flex;align-items:center;gap:10px;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
  padding-bottom:10px;border-bottom:2px solid var(--a100);
}
.hub-section-title::before{
  content:"";display:inline-block;width:14px;height:3px;
  background:var(--a400);border-radius:2px;
}
.story-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:clamp(12px,2.5vw,18px);}
.story-card{
  display:block;background:var(--paper-card);
  border:1px solid var(--line);border-radius:12px;
  padding:clamp(18px,3vw,24px);
  box-shadow:0 1px 5px rgba(0,0,0,.04);
  transition:box-shadow .2s,transform .15s,border-color .15s;
  cursor:pointer;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.story-card:hover{
  box-shadow:0 6px 24px rgba(0,0,0,.11);
  transform:translateY(-2px);
  border-color:var(--a400);
}
.story-card-top{display:flex;align-items:flex-start;justify-content:space-between;margin-bottom:10px;gap:8px;}
.story-card-code{
  display:inline-flex;align-items:center;justify-content:center;
  min-width:42px;height:28px;border-radius:6px;padding:0 8px;
  background:var(--a400);color:#fff;font-size:11px;font-weight:700;
  letter-spacing:.5px;flex-shrink:0;
}
.story-card-status{flex-shrink:0;}
.story-card h3{font-size:clamp(15px,2.2vw,18px);font-weight:600;color:var(--ink);margin-bottom:8px;line-height:1.25;}
.story-card-teaser{font-size:13px;color:var(--ink-faint);line-height:1.6;margin-bottom:12px;}
.story-card-arrow{
  display:flex;align-items:center;gap:6px;
  font-size:12px;font-weight:600;color:var(--a600);
}
.story-card-arrow::after{content:"→";transition:transform .15s;}
.story-card:hover .story-card-arrow::after{transform:translateX(3px);}

/* ── FOOTER ── */
.pagefoot{
  background:var(--a900,var(--a800));color:var(--a100);text-align:center;
  padding:clamp(18px,4vw,28px) clamp(16px,5vw,28px);font-size:13px;line-height:1.8;
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
}
.pagefoot a{color:#fff;font-weight:600;}
.pagefoot a:hover{text-decoration:underline;}

/* ── MOBILE TOC BTN ── */
.mob-toc{
  display:none;position:fixed;bottom:18px;right:16px;
  width:44px;height:44px;border-radius:9px;
  background:var(--a800);color:#fff;border:1px solid var(--a400);
  font-size:20px;cursor:pointer;box-shadow:0 4px 16px rgba(0,0,0,.25);
  z-index:600;align-items:center;justify-content:center;
}

/* ── RESPONSIVE ── */
@media(max-width:860px){
  .layout{flex-direction:column;}
  .sidebar{
    display:none;position:fixed;inset:0;z-index:700;
    width:100%;max-height:100%;
    background:rgba(0,0,0,.55);padding:16px;
    overflow-y:auto;
  }
  .sidebar.open{display:block;}
  .toc{max-width:300px;margin-left:auto;}
  .mob-toc{display:flex;}
  .main{width:100%;}
}
@media(max-width:520px){
  .story-grid{grid-template-columns:1fr;}
}
@media print{
  .topnav,.topbar,.sidebar,.pagefoot,#progressBar,.mob-toc{display:none;}
  .layout{display:block;}
  .card{break-inside:avoid;box-shadow:none;}
}