:root{
  --paper:#f5efe3;--card:#fffcf6;--ink:#1f1a14;--muted:#665a4b;--rule:#e0d4bf;
  --accent:#7a2e1f;--accent-soft:#f3e2da;--brass:#9a7128;--focus:#2f5d8a;
  --radius:10px;--shadow:0 1px 2px rgba(60,40,10,.06),0 4px 16px rgba(60,40,10,.06);
  color-scheme:light;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --paper:#15120e;--card:#1e1a15;--ink:#eee5d5;--muted:#b0a28c;--rule:#382f25;
  --accent:#e08b72;--accent-soft:#3a231c;--brass:#d6ab5c;--focus:#8fb7e0;
  --shadow:none;color-scheme:dark;
}}
:root[data-theme="dark"]{
  --paper:#15120e;--card:#1e1a15;--ink:#eee5d5;--muted:#b0a28c;--rule:#382f25;
  --accent:#e08b72;--accent-soft:#3a231c;--brass:#d6ab5c;--focus:#8fb7e0;
  --shadow:none;color-scheme:dark;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);
  font:17px/1.65 system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif}
h1,h2,h3,.brand{font-family:"Libre Caslon Text",Georgia,"Times New Roman",serif;line-height:1.25;font-weight:700}
h1{font-size:clamp(1.8rem,4.5vw,2.6rem);margin:.2em 0 .3em}
h2{font-size:1.45rem;margin:2em 0 .5em}
h3{font-size:1.1rem;margin:1.4em 0 .3em}
a{color:var(--accent);text-underline-offset:2px}
a:hover{text-decoration-thickness:2px}
:focus-visible{outline:3px solid var(--focus);outline-offset:2px;border-radius:4px}
.wrap{max-width:860px;margin:0 auto;padding:0 16px}
.skip{position:absolute;left:-999px}.skip:focus{left:16px;top:8px;background:var(--card);padding:8px;z-index:9}

/* header / footer */
.site-head{border-bottom:1px solid var(--rule);background:var(--card)}
.site-head .wrap{display:flex;align-items:center;gap:16px;min-height:62px;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:10px;color:var(--ink);text-decoration:none;font-size:1.2rem}
.brand svg{width:34px;height:34px;flex:none}
.nav{display:flex;gap:4px 18px;flex-wrap:wrap;margin-left:auto;font-size:.95rem}
.nav a{color:var(--muted);text-decoration:none;padding:6px 0}
.nav a:hover,.nav a[aria-current]{color:var(--ink)}
.site-foot{margin-top:64px;border-top:1px solid var(--rule);padding:28px 0 40px;color:var(--muted);font-size:.9rem}
.site-foot nav{display:flex;flex-wrap:wrap;gap:6px 18px;margin-bottom:10px}
.site-foot a{color:var(--muted)}

.crumbs{font-size:.88rem;color:var(--muted);margin:22px 0 0}
.crumbs a{color:var(--muted)}
.lede{font-size:1.1rem;color:var(--muted);max-width:42em}

/* tool card */
.tool{background:var(--card);border:1px solid var(--rule);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:22px;margin:22px 0}
.tool h2{margin-top:0}
.fields{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}
.fields.two{grid-template-columns:repeat(2,minmax(0,1fr))}
.field{display:flex;flex-direction:column;gap:4px;min-width:0}
.field>span{font-size:.82rem;color:var(--muted);font-weight:600;letter-spacing:.01em}
input,select,button{font:inherit;color:inherit}
input,select{width:100%;padding:10px 12px;border:1px solid var(--rule);border-radius:8px;
  background:var(--paper);min-height:46px;font-size:1.05rem}
input:focus,select:focus{border-color:var(--focus)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;border:0;border-radius:8px;
  background:var(--accent);color:#fff;padding:10px 18px;min-height:44px;font-weight:600;cursor:pointer}
:root[data-theme="dark"] .btn{color:#1a120e}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .btn{color:#1a120e}}
.btn.ghost{background:transparent;color:var(--accent);border:1px solid var(--rule)}
.btn.small{min-height:36px;padding:6px 12px;font-size:.92rem}
.result{display:block;margin-top:18px;padding:16px 18px;border-radius:8px;background:var(--accent-soft);min-height:84px}
.result .big{font-family:"Libre Caslon Text",Georgia,serif;font-size:clamp(1.6rem,5vw,2.2rem);font-weight:700;line-height:1.2;display:block;word-break:break-word}
.result .sub{color:var(--muted);font-size:.95rem;margin-top:4px;display:block}
.result .sub a{font-weight:600}
.hint{font-size:.88rem;color:var(--muted);margin:10px 0 0}

/* calculator list */
.rows{display:flex;flex-direction:column;gap:10px}
.row{display:grid;grid-template-columns:64px repeat(4,minmax(0,1fr)) 40px;gap:8px;align-items:end}
.row select.sign{padding:10px 6px;text-align:center}
.row .del{border:1px solid var(--rule);background:transparent;border-radius:8px;min-height:46px;cursor:pointer;color:var(--muted)}
.actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:14px}
.opgrid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr)) 120px 1fr;gap:10px;align-items:end}

/* content */
.prose p,.prose li{max-width:42em}
table{border-collapse:collapse;width:100%;margin:14px 0;font-size:.96rem}
th,td{text-align:left;padding:9px 10px;border-bottom:1px solid var(--rule);vertical-align:top}
th{font-size:.84rem;color:var(--muted);text-transform:uppercase;letter-spacing:.04em}
.table-scroll{overflow-x:auto}
details{border-bottom:1px solid var(--rule);padding:12px 0}
summary{cursor:pointer;font-weight:600}
details p{margin:.5em 0 0}

.cards{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin:16px 0}
.card{display:block;background:var(--card);border:1px solid var(--rule);border-radius:var(--radius);
  padding:18px;text-decoration:none;color:var(--ink);box-shadow:var(--shadow)}
.card:hover{border-color:var(--brass)}
.card strong{font-family:"Libre Caslon Text",Georgia,serif;font-size:1.12rem;display:block;margin-bottom:4px;color:var(--accent)}
.card span{color:var(--muted);font-size:.95rem}
.kicker{font-size:.8rem;letter-spacing:.12em;text-transform:uppercase;color:var(--brass);font-weight:700;margin:28px 0 0}
.hero{padding:26px 0 6px}
.ad{margin:26px 0;min-height:0}
.note{border-left:3px solid var(--brass);padding:4px 0 4px 14px;color:var(--muted);margin:18px 0}

@media (max-width:640px){
  body{font-size:16px}
  .fields{grid-template-columns:repeat(2,minmax(0,1fr))}
  .cards{grid-template-columns:1fr}
  .row{grid-template-columns:56px repeat(2,minmax(0,1fr)) 40px;
    grid-template-areas:"sign l s del" "sign d f del";padding-bottom:10px;border-bottom:1px dashed var(--rule)}
  .row>.sign{grid-area:sign;align-self:stretch}
  .row>.fl{grid-area:l}.row>.fs{grid-area:s}.row>.fd{grid-area:d}.row>.ff{grid-area:f}
  .row>.del{grid-area:del;align-self:stretch}
  .opgrid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .tool{padding:16px}
  .nav{margin-left:0}
}
[hidden]{display:none!important}
.theme-btn{width:40px;padding:0}.theme-btn svg{width:18px;height:18px}
.fields.datef{grid-template-columns:90px 1fr 120px}
.fields.regf{grid-template-columns:1.4fr 110px 90px 1fr}
@media (max-width:640px){
  .fields.datef{grid-template-columns:72px 1fr 96px}
  .fields.regf{grid-template-columns:1fr 1fr}
  .fields.regf>.field:first-child{grid-column:1/-1}
}