:root{
  --bg:#faf7f1; --paper:#ffffff; --ink:#24211c; --muted:#6c6457; --line:#e7e0d2;
  --brand:#7a3e1d; --brand-ink:#ffffff; --brand-soft:#f3e7dc; --accent:#2f5d50; --warn:#9a3412; --ok:#166534;
  --radius:12px; --shadow:0 1px 2px rgba(40,30,10,.06),0 6px 24px rgba(40,30,10,.06);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:400 18px/1.75 "Sarabun",Tahoma,sans-serif}
h1,h2,h3{font-family:"Noto Serif Thai","Sarabun",serif;line-height:1.35;margin:0 0 .5em}
h1{font-size:clamp(28px,5.2vw,44px);font-weight:700}
h2{font-size:clamp(23px,3.6vw,30px);font-weight:700}
h3{font-size:20px;font-weight:600}
p{margin:0 0 1em}
a{color:var(--brand)}
.wrap{max-width:1040px;margin:0 auto;padding:0 16px}
.narrow{max-width:720px;margin:0 auto;padding:0 16px}
header.top{border-bottom:1px solid var(--line);background:var(--paper)}
header.top .wrap{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:60px}
.brand{font-family:"Noto Serif Thai",serif;font-weight:700;color:var(--ink);text-decoration:none;font-size:19px}
.btn{display:inline-block;border:0;border-radius:10px;padding:13px 22px;font:600 17px/1.2 "Sarabun",sans-serif;text-decoration:none;cursor:pointer;text-align:center}
.btn-primary{background:var(--brand);color:var(--brand-ink)}
.btn-primary:hover{filter:brightness(1.07)}
.btn-ghost{background:transparent;color:var(--brand);box-shadow:inset 0 0 0 2px var(--brand)}
.btn-small{padding:8px 14px;font-size:15px}
.btn[disabled]{opacity:.55;cursor:not-allowed}
section{padding:56px 0}
section.alt{background:var(--paper);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.hero{padding:48px 0 40px}
.hero-grid{display:grid;grid-template-columns:1.25fr .75fr;gap:40px;align-items:center}
.eyebrow{color:var(--accent);font-weight:600;letter-spacing:.02em;margin-bottom:8px}
.lead{font-size:20px;color:var(--muted)}
.price{font-size:30px;font-weight:700;font-family:"Noto Serif Thai",serif}
.price small{font-size:16px;color:var(--muted);font-weight:400}
.cta-row{display:flex;flex-wrap:wrap;gap:12px;align-items:center;margin:18px 0 10px}
.fine{font-size:14px;color:var(--muted)}
.cover{aspect-ratio:3/4;border-radius:6px 14px 14px 6px;background:linear-gradient(160deg,#3b1c0e 0%,#7a3e1d 55%,#a8643a 100%);color:#fbf3e8;padding:28px 24px;display:flex;flex-direction:column;justify-content:space-between;box-shadow:0 18px 40px rgba(60,25,5,.28),inset 6px 0 0 rgba(0,0,0,.18);max-width:320px;margin-left:auto}
.cover .c-top{font-size:13px;letter-spacing:.12em;opacity:.85}
.cover .c-title{font-family:"Noto Serif Thai",serif;font-size:30px;font-weight:700;line-height:1.25}
.cover .c-sub{font-size:15px;opacity:.9;line-height:1.5}
.cover .c-author{font-family:"Noto Serif Thai",serif;font-size:18px;border-top:1px solid rgba(255,255,255,.35);padding-top:10px}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:20px}
.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.card{background:var(--paper);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
.card h3{margin-bottom:6px}
.num{display:inline-flex;align-items:center;justify-content:center;width:34px;height:34px;border-radius:50%;background:var(--brand-soft);color:var(--brand);font-weight:700;margin-bottom:8px}
.toc{counter-reset:ch;list-style:none;padding:0;margin:0;display:grid;grid-template-columns:1fr 1fr;gap:10px 28px}
.toc li{counter-increment:ch;padding:10px 0;border-bottom:1px dashed var(--line)}
.toc li::before{content:"บทที่ " counter(ch);display:block;font-size:13px;color:var(--accent);font-weight:600}
.files{display:flex;flex-wrap:wrap;gap:10px;margin-top:14px}
.pill{background:var(--brand-soft);color:var(--brand);border-radius:999px;padding:6px 14px;font-size:15px;font-weight:600}
.checks{list-style:none;padding:0;margin:0}
.checks li{padding-left:30px;position:relative;margin:8px 0}
.checks li::before{content:"✓";position:absolute;left:0;color:var(--ok);font-weight:700}
.crosses li::before{content:"–";color:var(--muted)}
.author{display:grid;grid-template-columns:88px 1fr;gap:18px;align-items:start}
.avatar{width:88px;height:88px;border-radius:50%;background:var(--brand-soft);display:flex;align-items:center;justify-content:center;font-family:"Noto Serif Thai",serif;font-size:34px;color:var(--brand)}
form .field{margin-bottom:14px}
label{display:block;font-weight:600;margin-bottom:6px}
input[type=text],input[type=email]{width:100%;font:inherit;padding:12px 14px;border:1px solid #cfc6b4;border-radius:10px;background:#fff}
input:focus{outline:3px solid #e7c9b0;border-color:var(--brand)}
.check{display:flex;gap:10px;align-items:flex-start;font-weight:400;font-size:16px}
.check input{margin-top:6px;width:18px;height:18px;flex:0 0 auto}
.msg{border-radius:10px;padding:12px 14px;margin:12px 0;font-size:16px}
.msg.ok{background:#ecf7ef;color:var(--ok);border:1px solid #bfe3c8}
.msg.err{background:#fdf0e9;color:var(--warn);border:1px solid #f3cdb6}
.msg.info{background:#eef4f2;color:var(--accent);border:1px solid #c9ddd6}
details{background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:14px 18px;margin-bottom:10px}
summary{cursor:pointer;font-weight:600}
details p{margin:10px 0 0}
footer{padding:36px 0 48px;color:var(--muted);font-size:15px;border-top:1px solid var(--line);background:var(--paper)}
footer a{color:var(--muted)}
.qrbox{text-align:center}
.qrbox canvas,.qrbox img{width:260px;max-width:100%;height:auto;image-rendering:pixelated;border:10px solid #fff;box-shadow:var(--shadow)}
.amount-big{font-size:38px;font-weight:700;font-family:"Noto Serif Thai",serif;color:var(--brand)}
.steps{display:flex;gap:8px;margin-bottom:22px;flex-wrap:wrap}
.step{flex:1 1 0;min-width:90px;text-align:center;font-size:14px;padding:8px;border-radius:8px;background:#efe9de;color:var(--muted)}
.step.on{background:var(--brand);color:#fff}
.dl a{display:block;margin:8px 0}
.hidden{display:none!important}
.kbd{font-family:ui-monospace,Menlo,monospace;background:#f1ece2;padding:2px 6px;border-radius:6px}
@media (max-width:820px){
  .hero-grid,.grid2,.grid3{grid-template-columns:1fr}
  .cover{margin:0 auto;max-width:260px}
  .toc{grid-template-columns:1fr}
  section{padding:40px 0}
  body{font-size:17px}
}