/* Variant B — "protocol sheet": the look of a test record form. Public Sans (US Web Design System), white paper, graphite text, carbonless-blue rules, one red for the computed age. */
:root{--page:#fff;--ink:#2a2d31;--ink-2:#4d5259;--muted:#6f757d;--rule:#aab9cb;--rule-2:#d9e2ec;--rule-soft:#f1f5f9;--red:#b9121b;--red-soft:#fbe9ea;--card:#fff;--ok:#1b6e3a;--err:#b9121b;--sans:"Public Sans","Helvetica Neue",Arial,sans-serif;--mono:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace}
@media (prefers-color-scheme:dark){:root{--page:#15171a;--ink:#e9ebee;--ink-2:#c0c5cc;--muted:#8d949d;--rule:#4a5a6c;--rule-2:#2d3640;--rule-soft:#1c2026;--red:#ff5f66;--red-soft:#3a1e20;--card:#15171a}}
*{box-sizing:border-box}html{scroll-behavior:smooth}
body{margin:0;background:var(--page);color:var(--ink);font:16.5px/1.6 var(--sans);font-feature-settings:"tnum" 1}
a{color:var(--ink);text-decoration-color:var(--rule);text-underline-offset:3px}a:hover{color:var(--red)}
.wrap{max-width:920px;margin:0 auto;padding:0 20px}
header.site{border-bottom:3px double var(--rule)}
header.site .wrap{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:60px;flex-wrap:wrap}
.brand{font-weight:700;font-size:17px;letter-spacing:.01em;text-decoration:none;color:var(--ink)}.brand svg{display:none}
nav.main a{margin-left:20px;text-decoration:none;color:var(--ink-2);font-size:15px}nav.main a:hover{color:var(--red)}
main{padding:36px 0 56px}
h1{font-size:clamp(30px,4.4vw,42px);line-height:1.12;font-weight:700;letter-spacing:-.02em;margin:0 0 10px;max-width:24ch}
h1 em{font-style:normal;color:inherit}
h2{font-size:clamp(22px,2.8vw,27px);font-weight:700;margin:44px 0 10px;padding-top:14px;border-top:1px solid var(--rule-2);max-width:68ch}
h3{font-size:18px;font-weight:700;margin:22px 0 6px}
p{margin:0 0 14px}
p.lead{font-size:18px;color:var(--ink-2);margin:0 0 24px;max-width:62ch}
main > p,main > ul,main > ol,main > details,.note{max-width:68ch}
.card{background:var(--card);border:1px solid var(--rule);border-top:4px solid var(--ink);border-radius:2px;padding:22px 24px}
.tool{display:grid;grid-template-columns:1fr 1fr;gap:16px 24px}
@media (max-width:720px){.tool{grid-template-columns:1fr}}
label{display:block;font-weight:600;font-size:14px;margin-bottom:5px}
.hint{font-weight:400;color:var(--muted);font-size:13px}
input[type=date],input[type=text],input[type=number],select,textarea{width:100%;padding:10px 11px;border:1px solid var(--rule);border-radius:2px;background:var(--page);color:var(--ink);font:inherit;font-size:16px}
input:focus,select:focus,textarea:focus{outline:2px solid var(--ink);outline-offset:0}
textarea{min-height:140px;font-family:var(--mono);font-size:14px}
.row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;padding:11px 18px;border-radius:2px;border:1px solid var(--ink);background:var(--ink);color:var(--page);font:inherit;font-weight:600;cursor:pointer;min-height:44px}
.btn:hover{background:var(--red);border-color:var(--red);color:#fff}
.btn.secondary{background:transparent;color:var(--ink)}.btn.secondary:hover{background:var(--rule-soft);color:var(--ink)}
.btn.small{padding:5px 12px;min-height:32px;font-size:14px}
.results{margin-top:22px;padding-top:16px;border-top:1px solid var(--rule)}
.pill{display:block;font-size:14px;color:var(--ink-2);margin-bottom:2px}
.big{font-size:clamp(28px,4.4vw,38px);font-weight:700;letter-spacing:-.02em;line-height:1.15;color:var(--red)}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:0 20px;margin-top:14px;border-top:1px solid var(--rule-2)}
.stat{padding:10px 0;border-bottom:1px solid var(--rule-2)}
.stat .k{font-size:13px;color:var(--muted)}.stat .v{font-size:18px;font-weight:600}
.copyline{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:12px}
.mono{font-family:var(--mono);font-size:.95em}
.msg{margin-top:10px;font-size:14px}.msg.err{color:var(--err)}.msg.ok{color:var(--ok)}
table{width:100%;border-collapse:collapse;margin:12px 0;font-size:15px}
th,td{text-align:left;padding:8px 10px;border-bottom:1px solid var(--rule-2);vertical-align:top}
th{font-size:14px;font-weight:600;border-bottom:2px solid var(--rule)}
.table-wrap{overflow-x:auto}
details{border:0;border-bottom:1px solid var(--rule-2);padding:10px 0;margin:0;max-width:68ch}
summary{cursor:pointer;font-weight:600}details p{margin:8px 0 0;color:var(--ink-2)}
.toc{margin:24px 0 6px;font-size:14.5px;color:var(--muted);max-width:68ch}
.toc strong{font-weight:600;color:var(--ink);margin-right:6px}
.toc ol{display:inline;margin:0;padding:0;list-style:none}.toc li{display:inline}.toc li+li::before{content:", "}
.toc a{color:var(--ink-2)}
.note{border-left:3px solid var(--ink);padding:10px 14px;margin:18px 0;font-size:15.5px;background:var(--rule-soft)}
.related{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:14px}
.related a{display:block;padding:14px 0;border-top:2px solid var(--ink);text-decoration:none;color:var(--ink)}
.related a strong{display:block;font-size:17px;margin-bottom:4px}.related a span{color:var(--muted);font-size:14.5px}
.maker{max-width:68ch;margin:56px 0 0;padding:18px 0 0;border-top:3px double var(--rule);font-size:15.5px;color:var(--ink-2)}
.maker p{margin:0 0 8px}.maker .sig{color:var(--ink);font-weight:600}
footer.site{border-top:1px solid var(--rule-2);padding:22px 0 40px;color:var(--muted);font-size:14px;margin-top:40px}footer.site a{color:var(--muted);margin-right:16px}
.breadcrumb{font-size:14px;color:var(--muted);margin-bottom:10px}.breadcrumb a{color:var(--muted)}
.tabs{display:flex;gap:0;margin-bottom:-1px;flex-wrap:wrap}
.tabs button{padding:9px 16px;border:1px solid var(--rule);border-bottom:0;background:var(--rule-soft);color:var(--ink-2);font:inherit;font-weight:600;cursor:pointer;margin-right:-1px}
.tabs button[aria-selected=true]{background:var(--page);color:var(--ink);border-top:4px solid var(--ink);margin-bottom:-4px;position:relative;z-index:1}
.hidden{display:none!important}
.history{margin-top:16px;font-size:14px;color:var(--ink-2)}
kbd{font-family:var(--mono);border:1px solid var(--rule);border-bottom-width:2px;border-radius:3px;padding:1px 6px;font-size:13px}
@media print{header.site,footer.site,.related,.toc,nav,.btn,details:not([open]),.history,.maker{display:none!important}}
/* worked subtraction, as on a test record form */
.work{margin:14px 0 4px;border-collapse:collapse;width:auto;min-width:min(100%,420px);font-variant-numeric:tabular-nums}
.work th,.work td{border:0;padding:6px 14px 6px 0;text-align:right;font-size:17px}
.work th{font-weight:400;color:var(--muted);text-align:left;font-size:14px;padding-right:22px}
.work thead th{text-align:right;font-size:12.5px;color:var(--muted);border-bottom:1px solid var(--rule-2)}
.work thead th:first-child{text-align:left}
.work tr.minus td{border-bottom:1.5px solid var(--ink)}
.work tr.minus th{position:relative}
.work tr.minus th::before{content:"−";position:absolute;left:-14px;color:var(--ink)}
.work tr.age td{font-weight:700;color:var(--red)}
.work .was{display:block;font-size:12px;color:var(--muted);text-decoration:line-through;line-height:1}
.work .cap{caption-side:top;text-align:left;font-size:13px;color:var(--muted);padding:0 0 4px}