/* เลขคิด — contractfordifference.info — dark essay, single column */
@import url('https://fonts.googleapis.com/css2?family=Athiti:wght@500;600;700&family=Noto+Sans+Thai:wght@300;400;600&display=swap');
:root{--bg:#0F1F1A;--bg-2:#16302A;--ink:#EFE9DC;--ink-soft:#BDB6A6;--mustard:#D9A441;--rose:#C96A5B;--line:#2C4A41;--panel:#132A24}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font-family:'Noto Sans Thai',system-ui,sans-serif;font-weight:300;font-size:1.1rem;line-height:1.95}
a{color:var(--mustard);text-decoration:underline;text-decoration-color:rgba(217,164,65,.4);text-underline-offset:4px}
a:hover{text-decoration-color:var(--mustard)}
h1,h2,h3{font-family:'Athiti',sans-serif;color:var(--ink);line-height:1.25;margin:0}
h1{font-size:2.6rem;font-weight:700;letter-spacing:-.01em}
h2{font-size:1.65rem;font-weight:600;margin-top:3rem;color:var(--mustard)}
h2::before{content:"";display:block;width:48px;height:2px;background:var(--rose);margin-bottom:.9rem}
h2 + p, h2 + h3{margin-top:.9rem}
h3{font-size:1.2rem;font-weight:600;margin-top:1.7rem;color:var(--ink)}
p{margin:0 0 1.25rem}
strong{font-weight:600;color:#fff}
img{max-width:100%;height:auto;display:block}
.col{max-width:700px;margin:0 auto;padding:0 1.25rem}
.wide{max-width:960px;margin:0 auto;padding:0 1.25rem}
.top{border-bottom:1px solid var(--line)}
.top .wide{display:flex;align-items:baseline;justify-content:space-between;gap:1rem;padding-top:1.2rem;padding-bottom:1rem}
.logo{font-family:'Athiti',sans-serif;font-size:1.7rem;font-weight:700;color:var(--ink);text-decoration:none;letter-spacing:.04em}
.logo b{color:var(--rose);font-weight:700}
.nav{display:flex;flex-wrap:wrap;gap:1.3rem;font-size:.92rem}
.nav a{color:var(--ink-soft);text-decoration:none;padding-bottom:.25rem;border-bottom:2px solid transparent}
.nav a:hover{color:var(--ink)}
.nav a[aria-current]{color:var(--mustard);border-bottom-color:var(--mustard)}
.crumbs{font-size:.85rem;color:var(--ink-soft);margin:1.6rem 0 0}
.crumbs ol{list-style:none;padding:0;margin:0;display:flex;flex-wrap:wrap;gap:.4rem}
.crumbs li + li::before{content:"→";margin-right:.4rem;color:var(--rose)}
.crumbs a{color:var(--ink-soft)}
.hero{margin:2.5rem 0 2rem}
.hero .kicker{color:var(--rose);font-family:'Athiti',sans-serif;font-weight:600;font-size:1rem;margin-bottom:.6rem}
.hero .lede{font-size:1.25rem;color:var(--ink-soft);margin-top:1rem;font-weight:300}
.hero figure{margin:2rem 0 0}
.hero img{border-radius:2px}
.byline{font-size:.9rem;color:var(--ink-soft);margin-top:1.2rem;border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:.6rem 0}
.byline b{color:var(--ink);font-weight:600}
.toc{margin:2rem 0;padding:1.3rem 1.5rem;background:var(--panel);border-radius:4px;font-size:.95rem}
.toc strong{font-family:'Athiti',sans-serif;color:var(--mustard);display:block;margin-bottom:.4rem}
.toc ol{margin:0;padding-left:1.3rem;columns:2;column-gap:2rem}
.toc li{margin:.25rem 0;break-inside:avoid}
.toc a{color:var(--ink-soft);text-decoration:none}
.toc a:hover{color:var(--ink)}
.note{margin:1.8rem 0;padding:1.1rem 1.3rem 1.1rem 1.6rem;border-left:3px solid var(--mustard);background:var(--panel);font-size:1rem}
.note strong{color:var(--mustard);font-family:'Athiti',sans-serif;display:block;margin-bottom:.2rem}
.formula{margin:1.6rem 0;padding:1rem 1.3rem;background:#0A1512;border:1px solid var(--line);border-radius:4px;font-family:'Athiti',sans-serif;font-size:1.15rem;color:var(--mustard);text-align:center}
.formula small{display:block;color:var(--ink-soft);font-family:'Noto Sans Thai',sans-serif;font-size:.88rem;margin-top:.4rem}
ol.steps{padding-left:0;list-style:none;counter-reset:s;margin:1.4rem 0}
ol.steps li{counter-increment:s;position:relative;padding-left:2.8rem;margin:.9rem 0}
ol.steps li::before{content:counter(s);position:absolute;left:0;top:.15rem;width:1.9rem;height:1.9rem;border-radius:50%;border:1px solid var(--rose);color:var(--rose);font-family:'Athiti',sans-serif;font-weight:600;display:flex;align-items:center;justify-content:center;font-size:.95rem}
table{width:100%;border-collapse:collapse;margin:1.6rem 0;font-size:.95rem}
th{color:var(--mustard);text-align:left;font-weight:600;padding:.6rem .6rem;border-bottom:1px solid var(--mustard)}
td{padding:.6rem .6rem;border-bottom:1px solid var(--line);vertical-align:top;color:var(--ink)}
figure{margin:2rem 0}
figcaption{font-size:.85rem;color:var(--ink-soft);margin-top:.6rem}
.faq details{border-bottom:1px solid var(--line)}
.faq details:first-of-type{border-top:1px solid var(--line)}
.faq summary{cursor:pointer;padding:1rem 2rem 1rem 0;font-weight:600;color:var(--ink);list-style:none;position:relative;font-family:'Athiti',sans-serif;font-size:1.08rem}
.faq summary::after{content:"↓";position:absolute;right:0;top:1rem;color:var(--rose);transition:transform .2s}
.faq details[open] summary::after{transform:rotate(180deg)}
.faq details p{padding:0 0 1.2rem;margin:0;color:var(--ink-soft)}
.author{margin:3rem 0;padding:1.8rem 0;border-top:1px double var(--mustard);border-bottom:1px double var(--mustard);display:grid;grid-template-columns:96px 1fr;gap:1.4rem;align-items:start}
.author img{width:96px;height:96px;object-fit:cover;border-radius:2px;filter:sepia(.15)}
.author h3{margin:0;font-size:1.25rem}
.author .role{color:var(--rose);font-size:.9rem;margin:.1rem 0 .6rem;font-weight:600}
.author p{margin:0;font-size:.98rem;color:var(--ink-soft)}
.related{margin:2.5rem 0}
.related strong{font-family:'Athiti',sans-serif;color:var(--mustard)}
.related ul{list-style:none;padding:0;margin:.6rem 0 0}
.related li{padding:.55rem 0;border-bottom:1px solid var(--line)}
.related li a{text-decoration:none;color:var(--ink)}
.related li a:hover{color:var(--mustard)}
.disclaimer{margin:2.5rem 0;padding:1.2rem 1.4rem;background:var(--panel);border:1px solid var(--rose);font-size:.92rem;color:var(--ink-soft);border-radius:4px}
.disclaimer strong{color:var(--rose)}
.footer{border-top:1px solid var(--line);margin-top:3rem;padding:2rem 0 3rem;font-size:.88rem;color:var(--ink-soft)}
.footer .wide{display:flex;flex-wrap:wrap;justify-content:space-between;gap:1rem}
.footer a{color:var(--ink-soft)}
form{max-width:560px}
label{display:block;font-weight:600;margin:1rem 0 .3rem;color:var(--ink)}
input,textarea{width:100%;padding:.7rem .8rem;border:1px solid var(--line);background:var(--panel);color:var(--ink);font:inherit;border-radius:3px}
input:focus,textarea:focus{outline:2px solid var(--mustard)}
button{background:var(--mustard);color:var(--bg);border:0;padding:.75rem 1.5rem;font:inherit;font-weight:600;border-radius:3px;margin-top:1.2rem;cursor:pointer}
button:hover{background:var(--rose);color:#fff}
:target{scroll-margin-top:1rem}
@media (max-width:768px){
 .top .wide{flex-direction:column;align-items:flex-start;gap:.6rem}
 .nav{gap:.8rem;font-size:.88rem}
 h1{font-size:1.8rem}h2{font-size:1.35rem}
 body{font-size:1.02rem}
 .toc ol{columns:1}
 .author{grid-template-columns:1fr}
 table{display:block;overflow-x:auto}
}
@media print{.top,.nav,.footer,form,.toc,.related{display:none}body{background:#fff;color:#000}h1,h2,h3,a,td{color:#000}}