:root{
  --bg:#F2ECDD; --surface:#FFFDF7; --surface2:#FBF3DF; --raised:#FFFFFF;
  --ink:#241E16; --muted:#6E6250; --line:#E0D3B6; --line-strong:#CBB98F;
  --accent:#C64E14; --accent-ink:#FFF7EC; --accent-soft:#F3D9C4;
  --accent2:#2B5E86; --accent2-soft:#D6E3EB;
  --good:#256840; --good-soft:#DCEEE1; --bad:#A3352A; --bad-soft:#F6DDD8;
  --shadow:0 1px 0 rgba(36,30,22,.06);
  --radius:10px;
  --disp:'Oswald','Arial Narrow',system-ui,sans-serif;
  --body:'Inter',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  --mono:'IBM Plex Mono',ui-monospace,SFMono-Regular,Menlo,monospace;
  color-scheme:light;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    --bg:#181410; --surface:#211B15; --surface2:#251E17; --raised:#2A2219;
    --ink:#F1E7D6; --muted:#AC9E86; --line:#3B3123; --line-strong:#4B3F2C;
    --accent:#FF7A33; --accent-ink:#1B0F06; --accent-soft:#4A2A16;
    --accent2:#7FB3DE; --accent2-soft:#1E3140;
    --good:#57B37B; --good-soft:#1E3527; --bad:#E27567; --bad-soft:#3E2320;
    --shadow:0 1px 0 rgba(0,0,0,.3);
    color-scheme:dark;
  }
}
:root[data-theme="dark"]{
  --bg:#181410; --surface:#211B15; --surface2:#251E17; --raised:#2A2219;
  --ink:#F1E7D6; --muted:#AC9E86; --line:#3B3123; --line-strong:#4B3F2C;
  --accent:#FF7A33; --accent-ink:#1B0F06; --accent-soft:#4A2A16;
  --accent2:#7FB3DE; --accent2-soft:#1E3140;
  --good:#57B37B; --good-soft:#1E3527; --bad:#E27567; --bad-soft:#3E2320;
  --shadow:0 1px 0 rgba(0,0,0,.3);
  color-scheme:dark;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0; background:var(--bg); color:var(--ink); font:16px/1.6 var(--body); padding-bottom:env(safe-area-inset-bottom,0)}
img,svg{max-width:100%}
a{color:var(--accent2)}
a:hover{color:var(--accent)}
h1,h2,h3,.disp{font-family:var(--disp); text-transform:uppercase; letter-spacing:.02em; line-height:1.15}
.mono{font-family:var(--mono); font-variant-numeric:tabular-nums}
.skip{position:absolute; left:-999px}
.skip:focus{left:12px; top:12px; background:var(--ink); color:var(--bg); padding:8px 12px; z-index:10}
.wrap{max-width:1080px; margin:0 auto; padding:0 16px}

/* ---- header ---- */
.site-hdr{background:var(--surface); border-bottom:3px solid var(--ink); position:relative}
.site-hdr::after{content:""; position:absolute; left:0; right:0; bottom:-7px; height:4px; background:repeating-linear-gradient(90deg,var(--accent) 0 18px,transparent 18px 26px)}
.hdr-row{display:flex; align-items:center; justify-content:space-between; gap:12px; min-height:62px}
.brand{display:flex; align-items:center; gap:10px; text-decoration:none; color:var(--ink)}
.brand-mark{width:38px; height:38px; border-radius:8px; background:var(--ink); color:var(--accent); display:flex; align-items:center; justify-content:center; flex:none}
.brand-mark svg{width:24px; height:24px}
.brand-name{font-family:var(--disp); font-size:22px; letter-spacing:.03em; text-transform:uppercase; font-weight:600}
.brand-name b{color:var(--accent); font-weight:600}
.menu{position:relative}
.menu > summary{list-style:none; cursor:pointer; font-family:var(--disp); text-transform:uppercase; letter-spacing:.05em; font-size:14px; padding:10px 14px; border:1px solid var(--line-strong); border-radius:8px; background:var(--raised); user-select:none}
.menu > summary::-webkit-details-marker{display:none}
.menu > summary::after{content:" ▾"}
.menu[open] > summary::after{content:" ▴"}
.menu-list{position:absolute; right:0; top:calc(100% + 8px); z-index:20; width:min(300px,calc(100vw - 32px)); background:var(--surface); border:1px solid var(--line-strong); border-radius:10px; box-shadow:0 12px 30px rgba(0,0,0,.18); padding:6px; margin:0; list-style:none}
.menu-list a{display:block; padding:11px 12px; border-radius:7px; text-decoration:none; color:var(--ink); font-family:var(--disp); text-transform:uppercase; letter-spacing:.03em; font-size:15px}
.menu-list a:hover,.menu-list a[aria-current]{background:var(--surface2); color:var(--accent)}
.navbar{display:none}
@media (min-width:980px){
  .menu{display:none}
  .navbar{display:flex; flex-wrap:wrap; gap:2px; list-style:none; margin:0; padding:0}
  .navbar a{display:block; padding:8px 9px; border-radius:7px; text-decoration:none; color:var(--muted); font-family:var(--disp); text-transform:uppercase; letter-spacing:.03em; font-size:13.5px; white-space:nowrap}
  .navbar a:hover{color:var(--ink); background:var(--surface2)}
  .navbar a[aria-current]{color:var(--ink); background:var(--surface2); box-shadow:inset 0 -2px 0 var(--accent)}
}

/* ---- page ---- */
main{padding:26px 0 40px}
.crumbs{font-size:13px; color:var(--muted); margin:0 0 6px}
.crumbs a{color:var(--muted)}
.page-h1{font-size:clamp(26px,6vw,40px); margin:0 0 6px}
.lede{color:var(--muted); margin:0 0 18px; max-width:62ch}

/* ---- calculator card ---- */
.calc{background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); padding:16px; box-shadow:var(--shadow)}
@media (min-width:640px){ .calc{padding:22px} }
.calc-top{display:flex; justify-content:space-between; align-items:center; gap:10px; flex-wrap:wrap; margin-bottom:14px}
.calc-top h2{font-size:17px; margin:0; color:var(--accent2)}
.prec{display:flex; align-items:center; gap:8px; font-size:12px; color:var(--muted); text-transform:uppercase; letter-spacing:.06em}
.prec select{font:600 14px var(--mono); background:var(--raised); color:var(--ink); border:1px solid var(--line-strong); border-radius:7px; padding:8px 10px; min-height:40px}
.grid2{display:grid; grid-template-columns:1fr; gap:18px; align-items:start}
@media (min-width:860px){ .grid2{grid-template-columns:1.05fr .95fr; gap:22px} }
fieldset{border:0; margin:0; padding:0; min-width:0}
legend{font-family:var(--disp); text-transform:uppercase; font-size:13px; letter-spacing:.08em; color:var(--accent2); margin:0 0 10px; padding:0}
.fields{display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:12px 12px; margin-bottom:18px}
@media (min-width:640px){ .fields{grid-template-columns:repeat(auto-fit,minmax(170px,1fr)); gap:14px} }
.field label{display:block; font-size:13px; color:var(--muted); margin-bottom:5px; line-height:1.3}
.field input,.field select{width:100%; font:500 17px var(--mono); background:var(--raised); color:var(--ink); border:1px solid var(--line-strong); border-radius:8px; padding:11px 11px; min-height:48px}
.field input:focus,.field select:focus,.prec select:focus{outline:2px solid var(--accent2); outline-offset:1px}
.field input[aria-invalid="true"]{border-color:var(--bad); background:var(--bad-soft)}
.field .hint{font-size:12px; color:var(--muted); margin-top:4px; line-height:1.35}
.readout{background:var(--surface2); border:1px solid var(--line); border-radius:9px; padding:8px 14px}
.readout + .readout{margin-top:14px}
.stat{display:flex; justify-content:space-between; align-items:baseline; gap:12px; padding:10px 0; border-bottom:1px dashed var(--line)}
.stat:last-child{border-bottom:0}
.stat .k{font-size:14px; color:var(--muted); line-height:1.35}
.stat .v{font:600 17px var(--mono); text-align:right; white-space:nowrap}
.stat.big .k{color:var(--ink); font-weight:600}
.stat.big .v{font-size:24px; color:var(--accent)}
.pill{display:inline-block; font:500 11px var(--disp); padding:2px 8px; border-radius:99px; letter-spacing:.04em; text-transform:uppercase; margin-left:6px; vertical-align:1px}
.pill:empty{display:none}
.pill.good{background:var(--good-soft); color:var(--good)}
.pill.bad{background:var(--bad-soft); color:var(--bad)}
.note{font-size:14px; color:var(--muted); line-height:1.55; margin:14px 0 10px}
.note b{color:var(--ink)}
.note-box{background:var(--accent2-soft); border:1px solid var(--accent2); border-radius:8px; padding:10px 12px; font-size:13.5px; line-height:1.5; margin-top:14px}
.table-wrap{overflow-x:auto; -webkit-overflow-scrolling:touch; border:1px solid var(--line); border-radius:8px; max-height:420px; overflow-y:auto}
table{width:100%; border-collapse:collapse; font-size:14px}
th,td{text-align:right; padding:8px 10px; border-bottom:1px solid var(--line); font-family:var(--mono); white-space:nowrap}
th:first-child,td:first-child{text-align:left; font-family:var(--body); color:var(--muted)}
thead th{position:sticky; top:0; background:var(--surface); color:var(--muted); font:600 12px var(--body); text-transform:uppercase; letter-spacing:.04em}
tr:last-child td{border-bottom:0}
tr.hl td{color:var(--accent); font-weight:600}
.diagram{background:var(--surface2); border:1px solid var(--line); border-radius:9px; padding:12px; display:flex; align-items:center; justify-content:center}
.diagram svg{width:100%; max-width:320px; height:auto}
.btn{font:500 15px var(--disp); text-transform:uppercase; letter-spacing:.03em; background:var(--ink); color:var(--bg); border:0; border-radius:8px; padding:12px 16px; min-height:48px; cursor:pointer}
.btn.ghost{background:transparent; color:var(--ink); border:1px solid var(--line-strong)}
.btn.accent{background:var(--accent); color:var(--accent-ink)}
.row{display:flex; gap:8px; align-items:center; flex-wrap:wrap}

/* ---- tape ---- */
.tape-total{background:var(--ink); color:var(--bg); border-radius:9px; padding:14px 16px; text-align:right; margin-bottom:12px}
.tape-total .k{font-size:12px; text-transform:uppercase; letter-spacing:.06em; opacity:.75}
.tape-total .v{font:600 32px var(--mono)}
.tape-total .sub{font:500 14px var(--mono); opacity:.75}
.tape-list{list-style:none; margin:0 0 12px; padding:0; max-height:240px; overflow-y:auto; border:1px solid var(--line); border-radius:8px; background:var(--raised)}
.tape-list li{display:flex; justify-content:space-between; gap:10px; padding:8px 12px; font:500 15px var(--mono); border-bottom:1px solid var(--line)}
.tape-list li:last-child{border-bottom:0}
.tape-list .op{color:var(--muted); display:inline-block; width:20px}
.tape-list .empty{color:var(--muted); font:italic 14px var(--body)}
.tape-in{flex:1 1 200px; font:500 18px var(--mono); background:var(--raised); color:var(--ink); border:1px solid var(--line-strong); border-radius:8px; padding:11px 12px; min-height:48px}

/* ---- keypad ---- */
.calc-wrap{display:grid; grid-template-columns:1fr; gap:24px; align-items:start}
@media (min-width:860px){ .calc-wrap{grid-template-columns:minmax(320px,400px) 1fr} }
.device{background:linear-gradient(180deg,#332C24,#1E1913); border-radius:22px; padding:16px 12px 18px; box-shadow:0 10px 28px rgba(0,0,0,.35),inset 0 1px 0 rgba(255,255,255,.06); margin:0 auto; width:100%; max-width:400px}
.screen{background:#C9CEB2; color:#20261C; border-radius:9px; padding:12px 14px 10px; margin-bottom:14px; box-shadow:inset 0 2px 7px rgba(0,0,0,.35)}
.screen .mode{font:500 11px var(--mono); letter-spacing:.12em; text-transform:uppercase; opacity:.75; min-height:15px; display:flex; justify-content:space-between; gap:8px}
.screen .value{font:600 30px var(--mono); text-align:right; min-height:38px; word-break:break-all; line-height:1.15; margin-top:2px}
.screen .regs{display:flex; gap:9px; margin-top:8px; padding-top:6px; border-top:1px solid rgba(32,38,28,.25); font:500 10px var(--mono); letter-spacing:.05em}
.screen .regs span{opacity:.3}
.screen .regs span.on{opacity:1; font-weight:700}
.keys{display:grid; grid-template-columns:repeat(5,1fr); gap:7px}
.keys button{border:0; border-radius:8px; min-height:48px; padding:6px 2px; font:500 12.5px var(--disp); text-transform:uppercase; cursor:pointer; line-height:1.1; color:#EFE9DA; background:#4A4236; box-shadow:0 2px 0 rgba(0,0,0,.35),inset 0 1px 0 rgba(255,255,255,.07); touch-action:manipulation}
.keys button:active{transform:translateY(1px); box-shadow:0 1px 0 rgba(0,0,0,.35)}
.keys .fn{background:#D9581C; color:#FFF7EC}
.keys .num{background:#5A5142; font:600 18px var(--mono)}
.keys .op{background:#2B5E86; color:#fff; font:600 19px var(--mono)}
.keys .util{background:#403A2F; font-size:12px}
.keys .wide{grid-column:span 3}
.kp-help{font-size:14.5px; line-height:1.6}
.kp-help h3{font-size:15px; margin:18px 0 4px; color:var(--accent2)}
.kp-help h3:first-child{margin-top:0}
.kp-help dl{margin:0; display:grid; grid-template-columns:auto 1fr; gap:6px 12px}
.kp-help dt{font:600 13px var(--mono); color:var(--accent); white-space:nowrap}
.kp-help dd{margin:0; color:var(--muted)}

/* ---- ads / affiliate ---- */
.ad-slot{margin:26px auto; text-align:center}
.ad-slot.live{min-height:280px}
.ad-slot.live::before{content:"Advertisement"; display:block; font-size:11px; color:var(--muted); letter-spacing:.06em; text-transform:uppercase; margin-bottom:4px}
.tools{background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); padding:16px 18px; margin:22px 0}
.tools h2{font-size:18px; margin:0 0 4px}
.tools ul{margin:8px 0 6px; padding-left:20px}
.tools li{margin:6px 0}
.tools small{color:var(--muted)}

/* ---- article ---- */
.article{max-width:740px; margin:34px 0 0}
.article h2{font-size:24px; margin:34px 0 10px}
.article h3{font-size:18px; margin:24px 0 6px}
.article p,.article li{max-width:68ch}
.article ol,.article ul{padding-left:22px}
.article li{margin:6px 0}
.article figure{margin:20px 0; background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); padding:14px}
.article figure svg{display:block; margin:0 auto; width:100%; max-width:560px; height:auto}
.article figcaption{font-size:13.5px; color:var(--muted); text-align:center; margin-top:8px}
.article code,.article kbd{font:500 .92em var(--mono); background:var(--surface2); border:1px solid var(--line); border-radius:4px; padding:0 4px}
.faq details{background:var(--surface); border:1px solid var(--line); border-radius:9px; margin:10px 0; padding:0 16px}
.faq summary{cursor:pointer; font-weight:600; padding:14px 0; list-style-position:outside}
.faq details[open] summary{border-bottom:1px solid var(--line)}
.faq details p{margin:12px 0 14px}
.related{margin:34px 0 0}
.related h2{font-size:22px; margin:0 0 12px}
.cards{display:grid; grid-template-columns:repeat(auto-fill,minmax(230px,1fr)); gap:12px; list-style:none; margin:0; padding:0}
.cards a{display:flex; gap:12px; align-items:flex-start; height:100%; background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); padding:14px; text-decoration:none; color:var(--ink); box-shadow:var(--shadow)}
.cards a:hover{border-color:var(--accent)}
.cards .ic{width:40px; height:40px; flex:none; border-radius:8px; background:var(--ink); color:var(--accent); display:flex; align-items:center; justify-content:center}
.cards .ic svg{width:22px; height:22px}
.cards strong{display:block; font:600 16px var(--disp); text-transform:uppercase; letter-spacing:.02em}
.cards span{display:block; font-size:13.5px; color:var(--muted); line-height:1.4; margin-top:2px}
.disclaimer{margin:30px 0 0; padding:12px 14px; border-left:4px solid var(--accent); background:var(--surface); font-size:14px; color:var(--muted)}

/* ---- home ---- */
.hero{padding:10px 0 6px}
.hero .page-h1{font-size:clamp(30px,7vw,52px)}
.hero p{font-size:18px; color:var(--muted); max-width:58ch; margin:0 0 22px}

/* ---- footer ---- */
.site-ftr{border-top:1px solid var(--line); margin-top:20px; padding:24px 0 32px; color:var(--muted); font-size:14px}
.site-ftr nav{display:flex; flex-wrap:wrap; gap:6px 18px; margin-bottom:10px}
.site-ftr a{color:var(--muted)}
.site-ftr p{margin:6px 0; max-width:80ch}

/* ---- article diagrams ---- */
.article figure text{font:500 13px var(--mono); fill:var(--muted); letter-spacing:.03em}
.article figure text.acc{fill:var(--accent); font-weight:600}
.article figure text.acc2{fill:var(--accent2); font-weight:600}
.diagram text{font-family:var(--mono)}
.cards strong{color:var(--ink)}
.hero{padding-top:14px}
main.wrap{padding-top:28px; padding-bottom:40px}
@media (max-width:639px){ .kp-help dl{grid-template-columns:1fr; gap:2px} .kp-help dd{margin-bottom:8px} }
td.pick{background:var(--accent-soft); color:var(--accent); font-weight:700}
.calc-warn{margin:16px 0 0; padding:10px 12px; border-radius:8px; background:var(--bad-soft); color:var(--ink); font-size:13.5px; line-height:1.5; border-left:4px solid var(--bad)}
.field select{font:500 16px var(--body)}
@media (min-width:980px){ .navbar a{padding:8px 7px; font-size:13px} }