:root{
  --red:#7a1f1f;
  --red-deep:#4e1111;
  --red-mid:#8f2b25;
  --bronze:#b07a2c;
  --gold:#d9b25f;
  --gold-soft:#f0dca8;
  --cream:#fbf5e8;
  --paper:#fffdf8;
  --ink:#2b1b15;
  --muted:#6b574d;
  --line:#e6d6b3;
  --radius:14px;
  --shadow:0 6px 22px rgba(78,17,17,.14);
  --head:"Palatino Linotype","Book Antiqua",Palatino,Georgia,"Times New Roman",serif;
  --body:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{margin:0;font-family:var(--body);font-size:17px;line-height:1.7;color:var(--ink);background:var(--cream);
  background-image:radial-gradient(circle at 20% 0,rgba(217,178,95,.12),transparent 40%)}
img{max-width:100%;height:auto;display:block}
a{color:var(--red);text-underline-offset:3px}
a:hover{color:var(--red-deep)}
h1,h2,h3,h4{font-family:var(--head);line-height:1.25;color:var(--red-deep);margin:0 0 .5em}
h2{font-size:clamp(1.6rem,4.2vw,2.2rem)}
h3{font-size:clamp(1.25rem,3.2vw,1.5rem);margin-top:1.8em}
h4{font-size:1.1rem}
p{margin:0 0 1em}
.wrap{width:min(1120px,100% - 2rem);margin-inline:auto}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.skip{position:absolute;left:-999px;top:0;background:var(--gold);color:#000;padding:.6rem 1rem;z-index:100}
.skip:focus{left:0}
:focus-visible{outline:3px solid var(--bronze);outline-offset:2px}
.small{font-size:.92rem;color:var(--muted)}
.small.light{color:#f3e3c0}
.top-gap{margin-top:2rem}

/* header */
.site-header{position:sticky;top:0;z-index:50;background:linear-gradient(180deg,var(--red-deep),var(--red));color:#fff;border-bottom:3px solid var(--gold);box-shadow:0 2px 12px rgba(0,0,0,.25)}
.bar{display:flex;align-items:center;justify-content:space-between;gap:1rem;padding:.55rem 0}
.brand{display:flex;align-items:center;gap:.6rem;color:#fff;text-decoration:none}
.brand:hover{color:#fff}
.brand-mark{color:var(--gold);display:grid;place-items:center}
.brand-text{display:flex;flex-direction:column;line-height:1.15;font-family:var(--head)}
.brand-text strong{font-size:1.02rem;letter-spacing:.2px}
.brand-text em{font-size:.95rem;color:var(--gold);font-style:normal}
.main-nav{display:flex;gap:.2rem}
.main-nav a{color:#fbeacb;text-decoration:none;padding:.5rem .8rem;border-radius:999px;font-size:.95rem;font-weight:500;white-space:nowrap}
.main-nav a:hover{background:rgba(255,255,255,.12);color:#fff}
.main-nav a.active{background:var(--gold);color:var(--red-deep);font-weight:700}
.menu-btn{display:none;width:46px;height:46px;border:1px solid rgba(217,178,95,.7);background:transparent;border-radius:10px;cursor:pointer;position:relative}
.menu-btn .bars,.menu-btn .bars::before,.menu-btn .bars::after{position:absolute;left:11px;width:22px;height:2.5px;background:var(--gold);border-radius:2px;content:"";transition:.2s}
.menu-btn .bars{top:21px}
.menu-btn .bars::before{left:0;top:-7px}
.menu-btn .bars::after{left:0;top:7px}
.menu-btn[aria-expanded="true"] .bars{background:transparent}
.menu-btn[aria-expanded="true"] .bars::before{top:0;transform:rotate(45deg)}
.menu-btn[aria-expanded="true"] .bars::after{top:0;transform:rotate(-45deg)}

/* panels */
.js .panel{display:none}
.js .panel.is-active{display:block;animation:fade .35s ease}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
.panel{padding-bottom:3rem}
.sec-head{padding:2.2rem 0 1rem;text-align:center;max-width:780px;margin:0 auto}
.sec-head .lead{color:var(--muted)}
.sec-head h2::after{content:"";display:block;width:90px;height:4px;margin:.5rem auto 0;border-radius:4px;background:linear-gradient(90deg,var(--bronze),var(--gold),var(--bronze))}
.eyebrow{font-size:.82rem;letter-spacing:.14em;text-transform:uppercase;color:var(--bronze);font-weight:700;margin:0 0 .4rem}
.h-center{text-align:center}

/* hero */
.hero{background:linear-gradient(135deg,var(--red-deep) 0%,var(--red) 60%,#923127 100%);color:#fff;position:relative;overflow:hidden;padding:2.2rem 0 2.6rem}
.hero::after{content:"";position:absolute;inset:auto 0 0 0;height:6px;background:repeating-linear-gradient(90deg,var(--gold) 0 18px,var(--bronze) 18px 36px)}
.hero-grid{display:grid;grid-template-columns:1.05fr 1fr;gap:2rem;align-items:center}
.hero h1{color:#fff;font-size:clamp(2rem,6.5vw,3.3rem);margin-bottom:.4em}
.hero h1 span{display:block;color:var(--gold)}
.hero .eyebrow{color:var(--gold)}
.hero .lead{font-size:1.08rem;color:#fbeed6}
.hero-fig{margin:0}
.hero-fig img{border-radius:var(--radius);border:4px solid var(--gold);box-shadow:0 10px 30px rgba(0,0,0,.4);aspect-ratio:4/3;object-fit:cover;width:100%}
.hero-fig figcaption{font-size:.85rem;color:#f1d9a6;margin-top:.5rem;text-align:center}

.btn-row{display:flex;flex-wrap:wrap;gap:.7rem;margin:1.1rem 0}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:.4rem;padding:.8rem 1.4rem;border-radius:999px;font-weight:700;text-decoration:none;font-size:1rem;border:2px solid transparent;cursor:pointer;min-height:48px;text-align:center;transition:transform .15s,box-shadow .15s,background .15s}
.btn:hover{transform:translateY(-2px);box-shadow:var(--shadow)}
.btn-gold{background:linear-gradient(180deg,#e7c777,var(--bronze));color:#2b1208}
.btn-gold:hover{color:#2b1208;background:linear-gradient(180deg,#f0d489,#c08a35)}
.btn-ghost{border-color:var(--gold);color:#fff}
.btn-ghost:hover{background:rgba(255,255,255,.12);color:#fff}
.btn-red{background:var(--red);color:#fff}
.btn-red:hover{background:var(--red-deep);color:#fff}
.btn-ghost-dark{border-color:var(--red);color:var(--red);background:transparent}
.btn-ghost-dark:hover{background:var(--red);color:#fff}
.btn-big{font-size:1.15rem;padding:1rem 1.8rem}

/* facts */
.facts{list-style:none;margin:-1.4rem 0 2rem;padding:0;display:grid;grid-template-columns:repeat(4,1fr);gap:.8rem;position:relative;z-index:2}
.facts li{background:var(--paper);border:1px solid var(--line);border-top:4px solid var(--bronze);border-radius:var(--radius);padding:.9rem 1rem;box-shadow:var(--shadow);text-align:center;display:flex;flex-direction:column;gap:.15rem}
.facts b{font-family:var(--head);font-size:1.5rem;color:var(--red)}
.facts span{font-size:.88rem;color:var(--muted);line-height:1.4}

.intro .cols{display:grid;grid-template-columns:1fr 1fr;gap:1.6rem}
.intro h2{text-align:center}

/* 5 steps */
.steps5{list-style:none;padding:0;margin:1rem 0 2.4rem;display:grid;grid-template-columns:repeat(5,1fr);gap:.7rem;counter-reset:s}
.steps5 li{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:.9rem .6rem;text-align:center;display:flex;flex-direction:column;align-items:center;gap:.1rem;position:relative}
.steps5 li span{display:grid;place-items:center;width:38px;height:38px;border-radius:50%;background:var(--red);color:var(--gold);font-family:var(--head);font-weight:700;font-size:1.1rem;margin-bottom:.3rem}
.steps5 b{color:var(--red-deep);font-family:var(--head)}
.steps5 small{color:var(--muted);line-height:1.3}
.steps5.compact{margin:0}

/* cards */
.cards{display:grid;grid-template-columns:repeat(4,1fr);gap:1rem;margin:1rem 0 2rem}
.card{display:flex;flex-direction:column;background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;text-decoration:none;color:var(--ink);box-shadow:0 2px 8px rgba(78,17,17,.08);transition:transform .2s,box-shadow .2s}
.card:hover{transform:translateY(-4px);box-shadow:var(--shadow);color:var(--ink)}
.card img{aspect-ratio:4/3;object-fit:cover;width:100%}
.card img.top{object-position:top}
.card div{padding:.9rem 1rem 1.1rem}
.card h3{margin:0 0 .3rem;font-size:1.12rem}
.card p{margin:0;font-size:.92rem;color:var(--muted);line-height:1.5}

.note{background:#fff6dd;border-left:5px solid var(--bronze);border-radius:8px;padding:1rem 1.2rem;margin:1.6rem 0;font-size:.98rem}

/* tabs */
.tabs{display:flex;gap:.5rem;overflow-x:auto;padding:.4rem 0 .8rem;margin:1rem 0 .6rem;scrollbar-width:thin;-webkit-overflow-scrolling:touch}
.tabs button{flex:0 0 auto;font:inherit;font-weight:600;padding:.65rem 1.1rem;border-radius:999px;border:2px solid var(--bronze);background:var(--paper);color:var(--red-deep);cursor:pointer;min-height:46px}
.tabs button:hover{background:var(--gold-soft)}
.tabs button[aria-selected="true"]{background:var(--red);border-color:var(--red);color:var(--gold)}
.js .tabpanel{display:none}
.js .tabpanel.is-active{display:block;animation:fade .3s ease}
.tabpanel{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:1.2rem 1.2rem .6rem;box-shadow:0 2px 10px rgba(78,17,17,.07)}
.tabpanel>h3{margin-top:.2em}
.no-js .tabpanel{margin-bottom:1.5rem}
.no-js .tabs{display:none}

.gal{display:grid;grid-template-columns:repeat(2,1fr);gap:.8rem;margin:0 0 1.2rem}
.gal.three{grid-template-columns:repeat(3,1fr)}
.gal.many{grid-template-columns:repeat(3,1fr)}
.gal figure{margin:0}
.gal img{width:100%;aspect-ratio:4/3;object-fit:cover;border-radius:10px;border:2px solid var(--line);cursor:zoom-in;background:#eadfca}
.gal img.portrait{object-position:center 35%}
.gal figcaption{font-size:.84rem;color:var(--muted);margin-top:.3rem;line-height:1.4}

.two{display:grid;grid-template-columns:1fr 1fr;gap:1rem;margin:1rem 0}
.box{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:1rem 1.2rem}
.box h4{margin-bottom:.4em}
.box p:last-child{margin-bottom:0}
.tabpanel .box.fact{background:#f6ecd5;border-color:#e0c98f;border-left:5px solid var(--bronze)}
.tabpanel .box.fact.alt{background:#f9e9e4;border-color:#e4bfb6;border-left-color:var(--red)}
.tabpanel .box.legend{background:#fbeceb;border-color:#e4bfb6;border-left:5px solid var(--red)}
.tabpanel .box.fact h4{color:#7a5416}
.tabpanel .box.legend h4{color:var(--red)}
.try{background:var(--gold-soft);border-radius:10px;padding:.8rem 1rem;margin-top:1rem}
.sub{margin-top:1.2rem}

/* library */
.embed-book iframe{display:block;border-radius:10px;background:#fff;max-width:100%}
.toc{margin:0 0 .8rem;padding-left:1.3rem}
.toc li{margin-bottom:.35rem;line-height:1.45}
.toc i{display:block;color:var(--muted);font-size:.9rem}
.table-wrap{overflow-x:auto}
.gloss{width:100%;border-collapse:collapse;font-size:.97rem}
.gloss th,.gloss td{padding:.45rem .6rem;text-align:left;border-bottom:1px solid var(--line)}
.gloss th{background:var(--red);color:var(--gold);font-family:var(--head)}
.gloss tbody tr:nth-child(even){background:#fbf3df}
.info-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:1rem;margin:.6rem 0 1.5rem}
.info-grid figure{margin:0;background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:.6rem;box-shadow:0 2px 8px rgba(78,17,17,.08)}
.info-grid img{width:100%;height:auto;border-radius:8px;cursor:zoom-in}
.info-grid figcaption{text-align:center;font-weight:600;color:var(--red-deep);margin-top:.4rem}

/* challenge */
.gemini{background:linear-gradient(135deg,var(--red-deep),var(--red));color:#fff;border-radius:var(--radius);padding:1.4rem 1.4rem 1.2rem;border:3px solid var(--gold);box-shadow:var(--shadow)}
.gemini h3{color:var(--gold);margin-top:0}
.gemini .btn{margin:.4rem 0 1rem}
.embed-form{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:.5rem;overflow-x:auto;-webkit-overflow-scrolling:touch}
.embed-form iframe{display:block;margin:0 auto;max-width:100%;background:#fff}

/* ambassador */
.amb-top,.amb-bottom{display:grid;grid-template-columns:1fr 1fr;gap:1.5rem;align-items:center;margin:1.2rem 0}
.amb-top figure,.amb-bottom figure{margin:0}
.amb-top img,.amb-bottom img{border-radius:var(--radius);border:3px solid var(--gold);box-shadow:var(--shadow);cursor:zoom-in;aspect-ratio:4/3;object-fit:cover;width:100%}
.amb-top figcaption,.amb-bottom figcaption{font-size:.84rem;color:var(--muted);margin-top:.35rem}
.amb-top .steps5{grid-template-columns:1fr;gap:.5rem}
.amb-top .steps5 li{flex-direction:row;justify-content:flex-start;gap:.7rem;text-align:left;padding:.5rem .8rem}
.amb-top .steps5 li span{margin:0;flex:0 0 38px}
.amb-top .steps5 small{margin-left:auto;font-size:.88rem}
.amb-top h3{margin-top:0}
.mission{counter-reset:m;list-style:none;padding:0;display:grid;grid-template-columns:repeat(4,1fr);gap:.7rem;margin:.6rem 0 1rem}
.mission li{counter-increment:m;background:var(--paper);border:1px solid var(--line);border-top:4px solid var(--red);border-radius:var(--radius);padding:.8rem 1rem;line-height:1.5}
.mission li::before{content:"Việc " counter(m);display:block;font-size:.78rem;letter-spacing:.1em;text-transform:uppercase;color:var(--bronze);font-weight:700}
.ticks{list-style:none;padding:0;margin:0}
.ticks li{position:relative;padding-left:1.6rem;margin-bottom:.5rem;line-height:1.55}
.ticks li::before{content:"";position:absolute;left:0;top:.5em;width:.7rem;height:.7rem;background:var(--gold);border:2px solid var(--bronze);transform:rotate(45deg)}
.checklist{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:.8rem 1.2rem;display:grid;gap:.2rem}
.checklist label{display:flex;gap:.7rem;align-items:center;padding:.55rem 0;border-bottom:1px dashed var(--line);cursor:pointer;line-height:1.4}
.checklist input{width:24px;height:24px;accent-color:var(--red);flex:0 0 24px}
.check-result{margin:.6rem 0 0;font-weight:700;color:var(--red-deep)}
.check-result.ok{color:#2f6b2f}

/* footer */
.site-footer{background:var(--red-deep);color:#f1dfb8;padding:1.8rem 0 2.2rem;border-top:4px solid var(--gold);font-size:.92rem}
.site-footer p{margin-bottom:.6rem}
.foot-title{font-family:var(--head);color:var(--gold);font-size:1.2rem;margin-bottom:.4rem}

/* lightbox */
dialog#lightbox{border:0;padding:0;background:transparent;max-width:96vw;max-height:94vh;overflow:visible;color:#fff;text-align:center}
dialog#lightbox::backdrop{background:rgba(25,6,6,.88)}
#lbImg{max-width:96vw;max-height:80vh;width:auto;margin:0 auto;border-radius:10px;border:3px solid var(--gold);background:#000}
#lbCap{margin:.6rem 1rem 0;font-size:.95rem}
.lb-close{position:absolute;right:6px;top:-46px;width:44px;height:44px;border-radius:50%;border:2px solid var(--gold);background:var(--red-deep);color:var(--gold);font-size:1.7rem;line-height:1;cursor:pointer}

/* responsive */
@media (max-width:980px){
  .main-nav a{padding:.45rem .55rem;font-size:.88rem}
  .cards{grid-template-columns:repeat(2,1fr)}
  .facts{grid-template-columns:repeat(2,1fr)}
  .mission{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:860px){
  .menu-btn{display:block}
  .js .main-nav{position:absolute;left:0;right:0;top:100%;background:var(--red-deep);flex-direction:column;padding:.6rem 1rem 1rem;border-bottom:3px solid var(--gold);display:none;gap:.3rem}
  .js .main-nav.open{display:flex}
  .main-nav a{font-size:1.05rem;padding:.8rem 1rem;border-radius:10px}
  .no-js .main-nav{flex-wrap:wrap}
  .hero-grid,.intro .cols,.two,.amb-top,.amb-bottom{grid-template-columns:1fr}
  .hero{padding-top:1.5rem}
  .hero-fig{order:-1}
  .steps5{grid-template-columns:1fr 1fr}
  .steps5 li:last-child{grid-column:1/-1}
  .amb-top .steps5{grid-template-columns:1fr}
  .amb-top .steps5 li:last-child{grid-column:auto}
}
@media (max-width:640px){
  body{font-size:16.5px}
  .gal,.gal.three,.gal.many{grid-template-columns:1fr 1fr}
  .gal.three figure:last-child{grid-column:1/-1}
  .info-grid{grid-template-columns:1fr}
  .info-grid figure{max-width:440px;margin-inline:auto}
  .cards{grid-template-columns:1fr}
  .card{flex-direction:row}
  .card img{width:38%;aspect-ratio:1/1;flex:0 0 38%}
  .mission{grid-template-columns:1fr}
  .tabpanel{padding:1rem .9rem .4rem}
  .btn{width:100%}
  .btn-row{flex-direction:column}
  .brand-text strong{font-size:.95rem}
}
@media (max-width:420px){
  .facts{grid-template-columns:1fr 1fr;gap:.5rem}
  .facts b{font-size:1.2rem}
  .gal,.gal.many{grid-template-columns:1fr}
}
@media (prefers-reduced-motion:reduce){
  *{animation:none!important;transition:none!important;scroll-behavior:auto!important}
}
@media print{
  .site-header,.menu-btn,dialog{display:none}
  .js .panel,.js .tabpanel{display:block!important}
}