/* Plainsum — "graph paper and a pencil": cool paper ground, cobalt ink, a single marker-yellow highlight on results.
   Layout: inputs left, a "tape" result panel right; stacks on phones. */
:root{
  --bg:#F5F6F8; --paper:#FFFFFF; --ink:#141A2A; --muted:#5A6275; --line:#DADEE6; --grid:#E8EBF1;
  --accent:#2C47C9; --accent-soft:#E6EBFB; --mark:#FFE58A; --warn:#B4451F; --good:#1F7A4D;
  --f-display:"Bricolage Grotesque","Avenir Next","Segoe UI",sans-serif;
  --f-body:"Public Sans","Helvetica Neue",Arial,sans-serif;
  --f-num:"JetBrains Mono",ui-monospace,Menlo,Consolas,monospace;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --bg:#0F1320; --paper:#161B2B; --ink:#E7EAF3; --muted:#9AA3B8; --line:#2A3146; --grid:#1D2335;
  --accent:#8FA3FF; --accent-soft:#222B4D; --mark:#5C4A0E; --warn:#F09A72; --good:#6FD3A0; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0F1320; --paper:#161B2B; --ink:#E7EAF3; --muted:#9AA3B8; --line:#2A3146; --grid:#1D2335;
  --accent:#8FA3FF; --accent-soft:#222B4D; --mark:#5C4A0E; --warn:#F09A72; --good:#6FD3A0; color-scheme:dark}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--f-body);font-size:16px;line-height:1.6;
  padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px))}
a{color:var(--accent)}
.wrap{max-width:1080px;margin:0 auto}
.top{display:flex;flex-wrap:wrap;align-items:center;gap:10px 22px;padding-block:18px;border-bottom:2px solid var(--ink)}
.logo{font-family:var(--f-display);font-size:26px;font-weight:800;letter-spacing:-.03em;color:var(--ink);text-decoration:none;display:flex;align-items:center;gap:8px}
.logo i{display:inline-grid;place-items:center;width:28px;height:28px;border-radius:6px;background:var(--accent);color:var(--paper);font-style:normal;font-size:17px;font-weight:700}
.top nav{display:flex;gap:4px;overflow-x:auto;scrollbar-width:none;min-width:0;flex:1}
.top nav a{flex:0 0 auto;font-size:15px;font-weight:600;color:var(--ink);text-decoration:none;padding:6px 12px;border-radius:6px}
.top nav a:hover{background:var(--accent-soft)}
.top nav a[aria-current="page"]{background:var(--ink);color:var(--bg)}
a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
main{padding-block:30px 44px}
h1{font-family:var(--f-display);font-size:34px;line-height:1.15;letter-spacing:-.02em;margin:0 0 8px;text-wrap:balance}
.lead{color:var(--muted);margin:0 0 24px;max-width:64ch;font-size:17px}
.grid{display:grid;grid-template-columns:minmax(0,1.05fr) minmax(0,.95fr);gap:24px;align-items:start}
@media (max-width:780px){.grid{grid-template-columns:minmax(0,1fr)}}
.form{display:grid;gap:14px;background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:20px}
label{display:grid;gap:5px;font-size:14px;font-weight:600;color:var(--ink)}
.hint{font-weight:400;font-size:12.5px;color:var(--muted)}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:12px;align-items:end}
.row3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;align-items:end}
@media (max-width:440px){.row3{grid-template-columns:1fr 1fr}}
input,select{font:inherit;font-size:16px;color:var(--ink);background:var(--bg);border:1px solid var(--line);border-radius:8px;padding:10px 12px;width:100%}
.unit{position:relative}
.unit input{font-family:var(--f-num);text-align:right}
.unit.pre input{padding-left:26px}.unit.post input{padding-right:40px}
.unit .u{position:absolute;top:50%;transform:translateY(-50%);color:var(--muted);font-size:14px;font-weight:500;pointer-events:none}
.unit.pre .u{left:11px}.unit.post .u{right:11px}
.seg{display:flex;flex-wrap:wrap;gap:6px}
.seg button{font:inherit;font-size:14px;font-weight:600;padding:7px 12px;border-radius:6px;border:1px solid var(--line);background:var(--bg);color:var(--ink);cursor:pointer}
.seg button[aria-pressed="true"]{background:var(--ink);color:var(--bg);border-color:var(--ink)}
.tape{background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:22px;min-width:0;
  background-image:linear-gradient(var(--grid) 1px,transparent 1px);background-size:100% 28px;background-position:0 -1px}
@media (min-width:781px){.tape{position:sticky;top:16px}}
.tape .k{font-size:13px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.big{font-family:var(--f-num);font-size:38px;font-weight:700;line-height:1.15;margin:4px 0 16px;font-variant-numeric:tabular-nums;word-break:break-word}
.big span.hl{background:linear-gradient(transparent 55%,var(--mark) 55%);padding:0 2px}
.big small{font-family:var(--f-body);font-size:16px;font-weight:500;color:var(--muted);margin-left:6px}
.big.warn{color:var(--warn);font-size:22px;font-family:var(--f-body)}
dl{margin:0;display:grid;grid-template-columns:minmax(9em,1fr) minmax(0,auto);background:var(--paper);border-top:1px solid var(--line)}
dt,dd{margin:0;padding:9px 0;border-bottom:1px solid var(--line)}
dd{font-family:var(--f-num);text-align:right;font-variant-numeric:tabular-nums;padding-left:12px;overflow-wrap:anywhere}
dt.sum,dd.sum{font-weight:700;border-bottom:none;padding-top:12px}
.note{font-size:13px;color:var(--muted);margin:14px 0 0;background:var(--paper)}
.chart{margin-top:16px;background:var(--paper)}
.chart svg{display:block;width:100%;height:auto}
.legend{display:flex;flex-wrap:wrap;gap:6px 14px;font-size:12.5px;color:var(--muted);margin-top:6px}
.legend span::before{content:"";display:inline-block;width:10px;height:10px;border-radius:2px;margin-right:5px;vertical-align:-1px;background:var(--c)}
.tbl{overflow-x:auto;margin-block:14px}
.tbl.scroll{max-height:360px;overflow-y:auto;border:1px solid var(--line);border-radius:10px}
table{border-collapse:collapse;width:100%;font-size:14px;background:var(--paper)}
th,td{padding:8px 12px;border-bottom:1px solid var(--line);text-align:right;white-space:nowrap;font-variant-numeric:tabular-nums}
th{font-size:12.5px;color:var(--muted);font-weight:700;background:var(--bg);position:sticky;top:0}
td{font-family:var(--f-num)}
th:first-child,td:first-child{text-align:left;font-family:var(--f-body)}
.tbl.txt td,.tbl.txt th{text-align:left;white-space:normal;font-family:var(--f-body)}
.pc-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}
@media (max-width:860px){.pc-grid{grid-template-columns:minmax(0,1fr)}}
.pc-grid .form h2{font-size:16px;margin:0}
.pc-res{font-family:var(--f-num);font-size:24px;font-weight:700;color:var(--accent);word-break:break-word}
.ad-slot{margin-block:30px;min-height:100px;display:flex;justify-content:center}
.ad-slot:empty{display:none}
.article{max-width:70ch;margin-top:48px;border-top:2px solid var(--ink);padding-top:6px}
.article h2{font-family:var(--f-display);font-size:23px;letter-spacing:-.01em;margin:30px 0 8px;text-wrap:balance}
.article ul,.article ol{padding-left:22px}
.article li+li{margin-top:4px}
.formula{font-family:var(--f-num);font-size:14px;background:var(--paper);border:1px solid var(--line);border-left:4px solid var(--accent);border-radius:6px;padding:12px 14px;overflow-x:auto;white-space:nowrap}
details{border-bottom:1px solid var(--line);padding-block:11px}
summary{cursor:pointer;font-weight:700}
details p{margin:8px 0 0;color:var(--muted)}
.related{margin-top:40px}
.related h2{font-size:16px;margin:0 0 10px;font-family:var(--f-display)}
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chips a{font-size:14px;font-weight:600;text-decoration:none;color:var(--ink);border:1px solid var(--line);background:var(--paper);padding:6px 12px;border-radius:999px}
.chips a:hover{border-color:var(--accent);color:var(--accent)}
/* home */
.hero{padding-block:14px 6px}
.hero h1{font-size:46px;max-width:18ch}
@media (max-width:520px){.hero h1{font-size:34px}}
.hero h1 em{font-style:normal;background:linear-gradient(transparent 60%,var(--mark) 60%)}
.cat-sec{margin-top:34px}
.cat-sec h2{font-family:var(--f-display);font-size:22px;margin:0 0 12px;display:flex;align-items:baseline;gap:10px;flex-wrap:wrap}
.cat-sec h2 span{font-family:var(--f-body);font-size:14px;font-weight:400;color:var(--muted)}
.cards{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}
@media (max-width:860px){.cards{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:520px){.cards{gap:10px}}
.card{display:grid;gap:3px;background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:16px;text-decoration:none;color:var(--ink);min-width:0}
.card:hover{border-color:var(--accent)}
.card strong{font-size:16px}
.card span{font-size:13.5px;color:var(--muted)}
.prose{max-width:70ch}
.prose h2{font-family:var(--f-display);font-size:21px;margin:28px 0 8px}
footer{border-top:1px solid var(--line);padding-block:22px 40px;color:var(--muted);font-size:13px}
footer .links{display:flex;flex-wrap:wrap;gap:6px 18px;margin-bottom:10px}
footer a{color:var(--muted)}
.warn-text{color:var(--warn)}
@media (prefers-reduced-motion: reduce){*{transition:none!important;scroll-behavior:auto!important}}
.row2>*,.row3>*,label{min-width:0}
input[type="date"]{min-width:0;max-width:100%;-webkit-appearance:none;appearance:none;min-height:46px}
.timecard td,.timecard th{padding:6px 6px;font-size:13.5px}
.timecard input{padding:7px 6px;font-size:14px;min-width:0;width:100%}
.timecard input[type="time"]{-webkit-appearance:none;appearance:none;min-height:38px}
.timecard input[type="time"]{width:100%;max-width:8.5em}
@media (max-width:520px){.timecard th:last-child,.timecard td:last-child{display:none}.timecard td,.timecard th{padding:5px 3px}.timecard input{font-size:13px;padding:6px 4px}}
@media (max-width:520px){
  .timecard{table-layout:fixed;width:100%}
  .timecard th:nth-child(1){width:2.7em}.timecard th:nth-child(4){width:3.8em}
  .timecard input[type="time"]{max-width:none;font-size:12.5px;padding:6px 2px;letter-spacing:-.02em}
  .timecard th{font-size:11px}
}
@media (max-width:520px){
  .timecard input[type="time"]::-webkit-calendar-picker-indicator{display:none}
  .timecard th:nth-child(4){width:3.4em}
  .timecard th .hint{display:block;font-size:10px}
}
.timecard input[id^="hr-b"]{width:5em}
@media (max-width:520px){.timecard input[id^="hr-b"]{width:100%;text-align:center}}
.split{display:flex;height:22px;border-radius:6px;overflow:hidden;margin-top:14px;gap:2px}
.split i{display:block;min-width:3px}
.tbl td:first-child,.tbl th:first-child{text-align:left}
#st-src,#pc-state-note,#rt-limit{margin:0;padding:10px 12px;border:1px dashed var(--line);border-radius:8px}
#pc-state-note:empty,#rt-limit:empty{display:none}
[hidden]{display:none!important}
@media (max-width:600px){.top nav{flex-basis:100%;justify-content:space-between}.top nav a{font-size:14px;padding:6px 8px}}