/* The Useful Library — shared styles. Black & grey, modern. */
:root{
  --bg:#0A0A0B; --bg2:#111113; --card:#151517; --card2:#1B1B1E;
  --ink:#F4F4F5; --muted:#A1A1AA; --dim:#71717A;
  --line:#26262B; --line2:#34343A;
  --acc:#FFFFFF; --acc-ink:#0A0A0B;
  --panel:linear-gradient(160deg,#2A2A2F 0%,#151517 70%);
  --radius:20px;
  --sans:"Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --display:"Instrument Serif",Georgia,serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.65 var(--sans);-webkit-font-smoothing:antialiased;
  background-image:radial-gradient(900px 500px at 80% -10%,rgba(255,255,255,.06),transparent 60%)}
img{max-width:100%;height:auto;display:block}
a{color:inherit}
::selection{background:#fff;color:#000}
.wrap{max-width:1120px;margin:0 auto;padding:0 20px}
.narrow{max-width:740px}
h1,h2,h3{font-family:var(--sans);font-weight:600;letter-spacing:-.035em;line-height:1.08;margin:0 0 .5em}
h1{font-size:clamp(2.3rem,5.6vw,4rem)}
h2{font-size:clamp(1.8rem,3.8vw,2.7rem)}
h3{font-size:1.15rem;letter-spacing:-.015em;line-height:1.3}
h1 em,h2 em{font-family:var(--display);font-style:italic;font-weight:400;letter-spacing:-.01em;color:#D4D4D8}
p{margin:0 0 1em}
strong{color:var(--ink);font-weight:600}
.eyebrow{display:inline-flex;align-items:center;gap:8px;font:500 .78rem/1 var(--sans);letter-spacing:.08em;text-transform:uppercase;
  color:var(--muted);border:1px solid var(--line2);border-radius:999px;padding:7px 13px;margin-bottom:20px;background:rgba(255,255,255,.02)}
.eyebrow::before{content:"";width:6px;height:6px;border-radius:50%;background:#fff;opacity:.8}
.lead{font-size:1.15rem;color:var(--muted)}
section{padding:96px 0}
.alt{background:var(--bg2);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}

/* top bar */
.top{position:sticky;top:0;z-index:10;background:rgba(10,10,11,.72);backdrop-filter:saturate(160%) blur(14px);
  -webkit-backdrop-filter:saturate(160%) blur(14px);border-bottom:1px solid var(--line)}
.top .wrap{display:flex;align-items:center;justify-content:space-between;height:64px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;font:600 1rem var(--sans);letter-spacing:-.02em}
.brand img{width:30px;height:30px;border-radius:8px;filter:grayscale(1)}
.top nav{display:flex;align-items:center}
.top nav a{font-size:.92rem;text-decoration:none;color:var(--muted);margin-left:22px;transition:color .15s}
.top nav a:hover{color:var(--ink)}
.top nav a.btn{color:var(--acc-ink);padding:9px 18px;font-size:.88rem}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;background:var(--acc);color:var(--acc-ink);text-decoration:none;
  font:600 1rem var(--sans);letter-spacing:-.01em;padding:15px 28px;border-radius:999px;
  box-shadow:0 0 0 1px rgba(255,255,255,.1),0 8px 30px rgba(255,255,255,.08);transition:transform .15s,box-shadow .15s,background .15s}
.btn:hover{transform:translateY(-1px);background:#E4E4E7;box-shadow:0 0 0 1px rgba(255,255,255,.2),0 12px 40px rgba(255,255,255,.14)}
.btn::after{content:"→";transition:transform .15s}
.btn:hover::after{transform:translateX(3px)}
.top nav a.btn::after{content:none}
.under-btn{font-size:.85rem;color:var(--dim);margin-top:14px}

/* hero */
.hero{padding:88px 0 96px}
.hero .wrap{display:grid;grid-template-columns:1.2fr .9fr;gap:64px;align-items:center}
.cover{background:var(--panel);border:1px solid var(--line);border-radius:28px;padding:44px;display:flex;justify-content:center;position:relative;overflow:hidden}
.cover::before{content:"";position:absolute;inset:auto -30% -40% -30%;height:70%;background:radial-gradient(closest-side,rgba(255,255,255,.08),transparent)}
.cover img{position:relative;width:76%;max-width:330px;border-radius:4px;box-shadow:0 30px 60px rgba(0,0,0,.6),0 0 0 1px rgba(255,255,255,.06)}

/* VSL hero: centered text, video, button */
.hero.vsl .wrap{display:block;max-width:900px;text-align:center}
.hero.vsl .lead{max-width:680px;margin:0 auto 34px}
.video{position:relative;aspect-ratio:16/9;border-radius:22px;overflow:hidden;border:1px solid var(--line2);background:#000;
  box-shadow:0 40px 100px rgba(0,0,0,.6),0 0 0 6px rgba(255,255,255,.03);margin:0 0 34px}
.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}

/* grids & cards */
.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.grid2{display:grid;grid-template-columns:repeat(2,1fr);gap:16px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:28px;transition:border-color .2s,background .2s}
.card:hover{border-color:var(--line2);background:var(--card2)}
.card h3{margin-bottom:.45em}
.card p{margin:0;color:var(--muted);font-size:.97rem}
.num{font:500 .8rem var(--sans);color:var(--dim);letter-spacing:.06em;margin-bottom:18px;display:block}
.shot{border-radius:16px;border:1px solid var(--line);overflow:hidden;background:var(--card)}
.caption{font-size:.88rem;color:var(--dim);margin-top:10px}

/* steps */
.steps{counter-reset:s;display:grid;gap:12px}
.step{display:grid;grid-template-columns:44px 1fr;gap:18px;align-items:start;background:var(--card);border:1px solid var(--line);border-radius:16px;padding:22px}
.step::before{counter-increment:s;content:counter(s,decimal-leading-zero);width:44px;height:44px;border-radius:12px;background:#fff;color:#000;
  display:flex;align-items:center;justify-content:center;font:600 .9rem var(--sans)}
.step h3{margin:.15em 0 .25em}
.step p{color:var(--muted);margin:0;font-size:.97rem}

/* checklist */
.check{list-style:none;padding:0;margin:0 0 26px}
.check li{padding:11px 0 11px 34px;position:relative;border-bottom:1px solid var(--line);color:#D4D4D8}
.check li::before{content:"";position:absolute;left:0;top:13px;width:20px;height:20px;border-radius:50%;background:#fff}
.check li::after{content:"";position:absolute;left:6px;top:19px;width:8px;height:4px;border-left:2px solid #000;border-bottom:2px solid #000;transform:rotate(-45deg)}

/* offer */
.offer{display:grid;grid-template-columns:.8fr 1.2fr;gap:52px;align-items:center;background:var(--card);border:1px solid var(--line2);border-radius:32px;padding:48px;
  box-shadow:0 40px 120px rgba(0,0,0,.5)}
.price{font:600 3.4rem/1 var(--sans);letter-spacing:-.04em;margin:8px 0 18px}
.price small{font:400 .95rem var(--sans);letter-spacing:0;color:var(--muted)}

/* honest note */
.note{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:28px 30px}
.note p{color:var(--muted)}

/* compare */
.vs{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.vs .card:first-child{opacity:.75}
.vs .card:last-child{border-color:var(--line2);background:linear-gradient(160deg,#1F1F23,#151517)}

/* faq */
details{border:1px solid var(--line);border-radius:16px;padding:20px 22px;margin-bottom:10px;background:var(--card);transition:border-color .2s}
details[open]{border-color:var(--line2)}
summary{cursor:pointer;font:500 1.03rem var(--sans);letter-spacing:-.01em;list-style:none;display:flex;justify-content:space-between;align-items:center;gap:16px}
summary::-webkit-details-marker{display:none}
summary::after{content:"+";flex:none;width:28px;height:28px;border-radius:50%;border:1px solid var(--line2);display:flex;align-items:center;justify-content:center;color:var(--muted);font:400 1.1rem/1 var(--sans);transition:transform .2s}
details[open] summary::after{transform:rotate(45deg)}
details p{color:var(--muted);margin:12px 0 0;font-size:.97rem}

/* library cards */
.books{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:18px}
.book{background:var(--card);border:1px solid var(--line);border-radius:24px;overflow:hidden;display:flex;flex-direction:column;text-decoration:none;transition:transform .2s,border-color .2s}
.book:hover{transform:translateY(-3px);border-color:var(--line2)}
.book .art{background:var(--panel);padding:34px;display:flex;justify-content:center;border-bottom:1px solid var(--line)}
.book .art img{height:250px;width:auto;border-radius:3px;box-shadow:0 20px 40px rgba(0,0,0,.6);transition:transform .25s}
.book:hover .art img{transform:scale(1.03) rotate(-1deg)}
.book .body{padding:24px 26px 28px;display:flex;flex-direction:column;gap:8px;flex:1}
.book .tag{font:500 .74rem var(--sans);letter-spacing:.08em;text-transform:uppercase;color:var(--dim)}
.book h3{margin:0;font-size:1.25rem}
.book p{margin:0;color:var(--muted);font-size:.96rem;flex:1}
.book .more{font-weight:600;font-size:.95rem;margin-top:10px}
.book.soon{border-style:dashed;background:transparent}
.book.soon:hover{transform:none}

footer{border-top:1px solid var(--line);padding:36px 0;font-size:.86rem;color:var(--dim)}
footer .wrap{display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap}
footer a{text-decoration:none;color:var(--muted)}

@media (max-width:820px){
  body{font-size:16px}
  section{padding:64px 0}
  .hero{padding:48px 0 64px}
  .hero .wrap,.offer,.grid2,.vs{grid-template-columns:1fr;gap:28px}
  .grid3{grid-template-columns:1fr}
  .offer{padding:26px 20px;border-radius:24px}
  .cover{padding:30px;border-radius:22px}
  .top nav a:not(.btn){display:none}
  .btn{width:100%}
  .top nav a.btn{width:auto}
  .step{padding:18px}
}