/* Hán Văn Sơn · dark minimal */
:root{
  --bg:#08090b; --bg2:#0e1013; --panel:#121418; --line:#1f2329; --line2:#2a2f37;
  --smoke:#8a9099; --text:#d9dce1; --white:#f3f5f7;
  --cold:#9fd3e6; --cold2:#5fa8c4; --steel:#c8d3dc; --danger:#c46a5f;
  --serif:"Playfair Display", "Times New Roman", serif;
  --sans:"Be Vietnam Pro", system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  --r:4px; --max:1120px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{background:var(--bg);color:var(--text);font-family:var(--sans);font-size:16px;line-height:1.7;-webkit-font-smoothing:antialiased;overflow-x:hidden}
body::before{content:"";position:fixed;inset:0;pointer-events:none;z-index:0;opacity:.035;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='3'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E")}
a{color:inherit;text-decoration:none}
img,svg{display:block;max-width:100%}
.wrap{max-width:var(--max);margin:0 auto;padding:0 22px;position:relative;z-index:1}
.narrow{max-width:760px}
.serif{font-family:var(--serif)}
.eyebrow{font-size:12px;letter-spacing:.28em;text-transform:uppercase;color:var(--cold2);font-weight:500}
.muted{color:var(--smoke)}
.cold{color:var(--cold)}
h1,h2,h3,h4{font-family:var(--serif);color:var(--white);font-weight:600;line-height:1.25}
h1{font-size:clamp(34px,6vw,64px);letter-spacing:-.01em}
h2{font-size:clamp(26px,3.6vw,40px)}
h3{font-size:22px}
.lead{font-size:clamp(17px,2vw,20px);color:var(--steel);max-width:640px}

/* Header */
.top{position:sticky;top:0;z-index:50;background:rgba(8,9,11,.82);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.top .wrap{display:flex;align-items:center;justify-content:space-between;height:62px}
.logo{display:flex;align-items:center;gap:10px;font-family:var(--serif);font-size:19px;color:var(--white);letter-spacing:.02em}
.logo svg{width:22px;height:22px;color:var(--cold)}
.nav{display:flex;gap:26px;font-size:14px;color:var(--smoke)}
.nav a:hover{color:var(--white)}
.nav-cta{border:1px solid var(--line2);padding:7px 14px;border-radius:var(--r);color:var(--white)!important}
@media(max-width:760px){.nav a:not(.nav-cta){display:none}}

/* Buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;padding:15px 28px;border-radius:var(--r);font-weight:600;font-size:15px;letter-spacing:.02em;cursor:pointer;border:1px solid transparent;transition:.2s;font-family:var(--sans)}
.btn-primary{background:var(--white);color:#07080a}
.btn-primary:hover{background:var(--cold);box-shadow:0 0 0 6px rgba(159,211,230,.08)}
.btn-ghost{border-color:var(--line2);color:var(--white);background:transparent}
.btn-ghost:hover{border-color:var(--cold2);color:var(--cold)}
.btn-block{width:100%}
.btn[disabled]{opacity:.5;cursor:not-allowed}

/* Hero */
.hero{position:relative;padding:110px 0 90px;overflow:hidden;border-bottom:1px solid var(--line)}
.hero::after{content:"";position:absolute;right:-12%;top:-30%;width:70vw;height:70vw;max-width:900px;max-height:900px;background:radial-gradient(circle,rgba(95,168,196,.10),transparent 60%);pointer-events:none}
.hero-grid{display:grid;grid-template-columns:1.3fr .9fr;gap:40px;align-items:center}
.hero h1 em{font-style:italic;color:var(--cold)}
.hero .lead{margin:26px 0 36px}
.hero-actions{display:flex;gap:14px;flex-wrap:wrap}
.hero-art{position:relative;aspect-ratio:3/4;max-width:380px;justify-self:end;width:100%}
.hero-art svg{width:100%;height:100%}
@media(max-width:860px){.hero{padding:70px 0 60px}.hero-grid{grid-template-columns:1fr}.hero-art{max-width:240px;justify-self:center;order:-1}}

/* Section */
section{padding:96px 0;position:relative}
.sec-head{margin-bottom:48px;max-width:720px}
.sec-head h2{margin:12px 0 14px}
.divider{height:1px;background:linear-gradient(90deg,transparent,var(--line2),transparent);border:0}

/* Truths strip */
.truths{display:grid;grid-template-columns:repeat(3,1fr);gap:1px;background:var(--line);border:1px solid var(--line)}
.truth{background:var(--bg);padding:34px 28px}
.truth .n{font-family:var(--serif);font-size:44px;color:var(--line2);line-height:1}
.truth h3{font-size:19px;margin:14px 0 8px}
.truth p{color:var(--smoke);font-size:15px}
@media(max-width:860px){.truths{grid-template-columns:1fr}}

/* Steps */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.step{border:1px solid var(--line);padding:26px;border-radius:var(--r);background:var(--bg2)}
.step b{font-family:var(--serif);color:var(--cold);font-size:28px;display:block;margin-bottom:8px}
.step p{font-size:15px;color:var(--smoke)}
@media(max-width:760px){.steps{grid-template-columns:1fr}}

/* Tier */
.tier-head{display:flex;align-items:baseline;gap:18px;flex-wrap:wrap;margin:0 0 26px;padding-bottom:16px;border-bottom:1px solid var(--line)}
.tier-head .eyebrow{color:var(--smoke)}
.tier-head h3{font-size:28px}
.tier-head p{color:var(--smoke);font-size:15px;flex-basis:100%}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:22px;margin-bottom:70px}

/* Book card */
.card{border:1px solid var(--line);background:var(--panel);border-radius:var(--r);overflow:hidden;display:flex;flex-direction:column;transition:.25s}
.card:hover{border-color:var(--line2);transform:translateY(-3px)}
.card .cover-mini{aspect-ratio:4/3;border-bottom:1px solid var(--line)}
.card-body{padding:22px;display:flex;flex-direction:column;gap:10px;flex:1}
.card h4{font-size:21px}
.card .sub{font-size:14px;color:var(--smoke)}
.card .hook{font-size:14px;color:var(--steel);font-style:italic;border-left:2px solid var(--line2);padding-left:12px;margin-top:4px}
.card-foot{margin-top:auto;padding-top:14px;display:flex;align-items:center;justify-content:space-between;gap:10px;border-top:1px dashed var(--line)}
.price{font-family:var(--serif);font-size:22px;color:var(--white)}
.price small{font-family:var(--sans);font-size:12px;color:var(--smoke);margin-left:4px}
.strike{color:var(--smoke);text-decoration:line-through;font-size:14px}
.link-arrow{font-size:13px;color:var(--cold);letter-spacing:.04em}
.card.featured{border-color:rgba(159,211,230,.35);box-shadow:0 0 0 1px rgba(159,211,230,.08),0 30px 60px -30px rgba(95,168,196,.25)}
.badge{display:inline-block;font-size:11px;letter-spacing:.2em;text-transform:uppercase;color:var(--cold);border:1px solid rgba(159,211,230,.35);padding:3px 9px;border-radius:2px;align-self:flex-start}

/* Bundles */
.bundles{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;margin-bottom:70px}
.bundle{border:1px solid var(--line2);padding:30px;border-radius:var(--r);background:linear-gradient(180deg,var(--panel),var(--bg));display:flex;flex-direction:column;gap:12px}
.bundle ul{list-style:none;font-size:14px;color:var(--steel)}
.bundle li{padding:6px 0;border-bottom:1px dashed var(--line)}
.bundle li::before{content:"♜ ";color:var(--cold2);font-size:12px}
.bundle .save{font-size:13px;color:var(--cold)}
@media(max-width:960px){.bundles{grid-template-columns:1fr}}

/* Premium */
.premium{border:1px solid rgba(159,211,230,.25);border-radius:var(--r);display:grid;grid-template-columns:.8fr 1.2fr;overflow:hidden;background:radial-gradient(ellipse at top left,rgba(95,168,196,.08),transparent 60%),var(--panel)}
.premium .cover-mini{border-right:1px solid var(--line);min-height:100%}
.premium-body{padding:40px;display:flex;flex-direction:column;gap:14px}
.premium ul{list-style:none;columns:2;font-size:14px;color:var(--steel)}
.premium li{padding:4px 0;break-inside:avoid}
.premium li::before{content:"— ";color:var(--cold2)}
@media(max-width:860px){.premium{grid-template-columns:1fr}.premium .cover-mini{aspect-ratio:16/9;border-right:0;border-bottom:1px solid var(--line)}.premium ul{columns:1}.premium-body{padding:26px}}

/* Quote band */
.band{padding:110px 0;text-align:center;border-top:1px solid var(--line);border-bottom:1px solid var(--line);background:var(--bg2)}
.band blockquote{font-family:var(--serif);font-size:clamp(24px,3.4vw,38px);color:var(--white);max-width:860px;margin:0 auto;line-height:1.4;font-style:italic}
.band cite{display:block;margin-top:22px;font-style:normal;color:var(--smoke);letter-spacing:.2em;font-size:12px;text-transform:uppercase}

/* Author */
.author{display:grid;grid-template-columns:.8fr 1.2fr;gap:56px;align-items:center}
.author-portrait{aspect-ratio:4/5;border:1px solid var(--line);background:var(--panel);display:flex;align-items:center;justify-content:center;color:var(--line2);position:relative;overflow:hidden}
.author-portrait img{width:100%;height:100%;object-fit:cover;filter:grayscale(1) contrast(1.1)}
.author-portrait .ph{font-size:12px;color:var(--smoke);text-align:center;padding:20px;position:absolute;bottom:0}
.author p{margin-bottom:16px;color:var(--steel)}
@media(max-width:860px){.author{grid-template-columns:1fr;gap:30px}.author-portrait{max-width:320px}}

/* FAQ */
.faq details{border-bottom:1px solid var(--line);padding:20px 0}
.faq summary{cursor:pointer;list-style:none;font-weight:500;color:var(--white);display:flex;justify-content:space-between;gap:20px;font-size:17px}
.faq summary::after{content:"+";color:var(--cold);font-size:22px;line-height:1}
.faq details[open] summary::after{content:"−"}
.faq details p{margin-top:12px;color:var(--smoke);font-size:15px}

/* Policy */
.policy h3{margin:34px 0 12px;font-size:20px}
.policy p,.policy li{color:var(--steel);font-size:15px}
.policy ul{padding-left:20px;margin:8px 0}
.policy li{margin:6px 0}

/* Footer */
footer{border-top:1px solid var(--line);padding:56px 0 40px;font-size:14px;color:var(--smoke)}
.foot{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:30px}
.foot h5{color:var(--white);font-size:13px;letter-spacing:.2em;text-transform:uppercase;margin-bottom:14px;font-weight:500}
.foot a{display:block;padding:3px 0}
.foot a:hover{color:var(--white)}
.copy{margin-top:40px;padding-top:20px;border-top:1px solid var(--line);font-size:12px}
@media(max-width:760px){.foot{grid-template-columns:1fr}}

/* Product page */
.p-hero{padding:70px 0 60px;border-bottom:1px solid var(--line)}
.p-grid{display:grid;grid-template-columns:.85fr 1.15fr;gap:56px;align-items:start}
.p-cover{position:sticky;top:90px}
.cover{aspect-ratio:3/4.3;border-radius:2px;box-shadow:0 40px 80px -30px #000,0 0 0 1px var(--line2);overflow:hidden}
.p-info h1{font-size:clamp(32px,4.6vw,52px);margin:12px 0 6px}
.p-info .subtitle{font-family:var(--serif);font-style:italic;font-size:21px;color:var(--steel)}
.p-info .hook{margin:26px 0;font-size:18px;color:var(--white);border-left:2px solid var(--cold2);padding:4px 0 4px 18px}
.meta{display:flex;gap:16px;flex-wrap:wrap;font-size:13px;color:var(--smoke);margin-bottom:26px}
.meta span{border:1px solid var(--line);padding:5px 12px;border-radius:2px}
.buybox{border:1px solid var(--line2);background:var(--panel);padding:24px;border-radius:var(--r);display:flex;flex-direction:column;gap:14px}
.buybox .price{font-size:34px}
.buybox .note{font-size:13px;color:var(--smoke)}
.who{display:grid;grid-template-columns:1fr 1fr;gap:22px;margin-top:40px}
.who > div{border:1px solid var(--line);padding:22px;border-radius:var(--r)}
.who h4{font-size:16px;font-family:var(--sans);font-weight:600;letter-spacing:.06em;text-transform:uppercase;margin-bottom:12px}
.who ul{list-style:none;font-size:15px;color:var(--steel)}
.who li{padding:6px 0 6px 22px;position:relative}
.who .yes li::before{content:"✓";position:absolute;left:0;color:var(--cold)}
.who .no li::before{content:"✕";position:absolute;left:0;color:var(--danger)}
.who .no h4{color:var(--danger)}
@media(max-width:860px){.p-grid{grid-template-columns:1fr;gap:36px}.p-cover{position:static;max-width:300px;margin:0 auto}.who{grid-template-columns:1fr}}

.toc{counter-reset:part}
.toc .part{border-top:1px solid var(--line);padding:22px 0;display:grid;grid-template-columns:260px 1fr;gap:20px}
.toc .part h4{font-size:18px}
.toc ol{padding-left:20px;color:var(--steel);font-size:15px}
.toc li{padding:3px 0}
@media(max-width:760px){.toc .part{grid-template-columns:1fr;gap:8px}}

/* Reading sample */
.reader{background:#0b0c0e;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.reader-head{text-align:center;margin-bottom:46px}
.reader-head .eyebrow{color:var(--cold)}
.reader article{font-family:var(--serif);font-size:19px;line-height:1.85;color:#cfd3d8}
.reader article p{margin:0 0 1.15em}
.reader article h3{font-size:24px;margin:2em 0 .8em;color:var(--white)}
.reader article strong{color:var(--white);font-weight:600}
.reader article em{color:var(--steel)}
.reader blockquote{margin:1.8em 0;padding:24px 28px;border-left:2px solid var(--cold);background:rgba(159,211,230,.04);font-style:italic;color:var(--white);font-size:21px}
.dropcap::first-letter{float:left;font-size:4.4em;line-height:.85;padding:6px 12px 0 0;color:var(--cold);font-family:var(--serif)}
.table-wrap{overflow-x:auto;margin:1.8em 0;border:1px solid var(--line2);border-radius:var(--r)}
.reader table{width:100%;border-collapse:collapse;font-family:var(--sans);font-size:14.5px;line-height:1.55;min-width:560px}
.reader th{background:var(--panel);color:var(--cold);text-align:left;padding:12px 14px;font-weight:600;font-size:13px;letter-spacing:.05em;text-transform:uppercase}
.reader td{padding:12px 14px;border-top:1px solid var(--line);color:var(--steel);vertical-align:top}
.sample-cut{position:relative;color:var(--smoke)!important;font-style:italic}
.sample-end{position:relative;margin-top:-120px;padding-top:140px;background:linear-gradient(180deg,transparent,#0b0c0e 45%);text-align:center}
.sample-end p{font-family:var(--sans);color:var(--smoke);font-size:14px;margin-bottom:18px;letter-spacing:.1em;text-transform:uppercase}

/* Sticky mobile buy bar */
.sticky-buy{position:fixed;left:0;right:0;bottom:0;z-index:60;background:rgba(14,16,19,.96);backdrop-filter:blur(10px);border-top:1px solid var(--line2);padding:12px 18px;display:none;align-items:center;justify-content:space-between;gap:14px;transform:translateY(100%);transition:.3s}
.sticky-buy.show{transform:none}
.sticky-buy .t{font-size:13px;color:var(--smoke);line-height:1.3}
.sticky-buy .t b{display:block;color:var(--white);font-family:var(--serif);font-size:18px}
@media(max-width:860px){.sticky-buy{display:flex}body.has-sticky{padding-bottom:76px}}

/* Checkout */
.co{padding:56px 0 90px}
.co-grid{display:grid;grid-template-columns:1.1fr .9fr;gap:40px;align-items:start}
.panel{border:1px solid var(--line2);background:var(--panel);border-radius:var(--r);padding:30px}
.field{display:flex;flex-direction:column;gap:7px;margin-bottom:18px}
.field label{font-size:13px;color:var(--steel);letter-spacing:.04em}
.field input{background:var(--bg);border:1px solid var(--line2);color:var(--white);padding:14px 15px;border-radius:var(--r);font-size:16px;font-family:var(--sans)}
.field input:focus{outline:none;border-color:var(--cold2);box-shadow:0 0 0 3px rgba(95,168,196,.15)}
.field small{font-size:12px;color:var(--smoke)}
.err{color:var(--danger);font-size:13px;min-height:18px}
.summary-line{display:flex;justify-content:space-between;gap:16px;padding:10px 0;border-bottom:1px dashed var(--line);font-size:15px}
.summary-total{display:flex;justify-content:space-between;padding-top:16px;font-size:15px}
.summary-total b{font-family:var(--serif);font-size:28px;color:var(--white)}
.qr-box{text-align:center}
.qr-box img{width:100%;max-width:320px;margin:0 auto 18px;background:#fff;border-radius:6px;padding:8px}
.bank-rows{text-align:left;margin:18px 0;font-size:15px}
.bank-rows div{display:flex;justify-content:space-between;gap:10px;padding:10px 0;border-bottom:1px dashed var(--line);align-items:center}
.bank-rows span{color:var(--smoke)}
.bank-rows b{color:var(--white);font-weight:600;text-align:right;word-break:break-all}
.copy-btn{background:none;border:1px solid var(--line2);color:var(--cold);font-size:11px;padding:3px 8px;border-radius:2px;cursor:pointer;margin-left:8px;font-family:var(--sans)}
.status{display:flex;align-items:center;justify-content:center;gap:10px;font-size:14px;color:var(--steel);margin:14px 0}
.pulse{width:9px;height:9px;border-radius:50%;background:var(--cold);animation:p 1.4s infinite}
@keyframes p{0%{box-shadow:0 0 0 0 rgba(159,211,230,.6)}100%{box-shadow:0 0 0 14px rgba(159,211,230,0)}}
.warn{font-size:13px;color:#e2c08d;border:1px solid rgba(226,192,141,.25);background:rgba(226,192,141,.05);padding:12px 14px;border-radius:var(--r);text-align:left}
.hidden{display:none!important}
@media(max-width:860px){.co-grid{grid-template-columns:1fr}.co-grid .side{order:-1}}

/* Reveal */
.rv{opacity:0;transform:translateY(18px);transition:opacity .8s ease,transform .8s ease}
.rv.in{opacity:1;transform:none}
@media(prefers-reduced-motion:reduce){.rv{opacity:1;transform:none}html{scroll-behavior:auto}}
.prem-cover{display:flex;align-items:center;justify-content:center;padding:36px;border-right:1px solid var(--line);background:radial-gradient(circle at 50% 40%,rgba(95,168,196,.12),transparent 70%)}
.prem-cover .cover{max-width:260px;width:100%}
@media(max-width:860px){.prem-cover{border-right:0;border-bottom:1px solid var(--line)}.prem-cover .cover{max-width:200px}}