/* One stylesheet for every lesson page. Brand: navy #0B2C3C, teal #0B5263, blue #0A84FF, orange #F75F1A, cream #FBF8F4. */
:root{--navy:#0B2C3C;--teal:#0B5263;--orange:#F75F1A;--cream:#FBF8F4;--blue:#0A84FF;--line:#e3ddd3;--muted:#5b6b75;--good:#1a8f5a;--bad:#c2410c}
*{box-sizing:border-box}
body{margin:0;background:var(--cream);color:#1d2a33;font:17px/1.6 Nunito,system-ui,sans-serif}
a{color:var(--blue)}
.wrap{max-width:860px;margin:0 auto;padding:0 16px}
header.top{background:var(--navy);color:#fff}
header.top .wrap{display:flex;justify-content:space-between;align-items:center;padding:14px 16px;gap:12px}
.brand{color:#fff;text-decoration:none;font-weight:800;font-size:20px;white-space:nowrap} .brand b{color:var(--orange)}
.brand span{font-weight:600}
.top-links{display:flex;gap:10px;align-items:center}
.top-links a{color:#fff;font-weight:700;text-decoration:none;font-size:14px}
.top-links a.pill{border:1px solid #ffffff55;padding:6px 12px;border-radius:999px}
.crumbs{font-size:14px;color:var(--muted);margin:18px 0 4px} .crumbs a{color:var(--muted)}
h1{font-size:34px;line-height:1.15;color:var(--navy);margin:4px 0 10px}
h2{font-size:25px;color:var(--navy);margin:38px 0 10px}
h3{font-size:18px;color:var(--teal);margin:0 0 6px}
.tags span{display:inline-block;font-size:13px;font-weight:700;padding:4px 10px;border-radius:999px;background:#fff;border:1px solid var(--line);margin:0 6px 6px 0}
.tags .code{background:var(--navy);color:#fff;font-family:"Space Mono",monospace;border-color:var(--navy)}
.mono{font-family:"Space Mono",monospace}
.lead{font-size:19px}
.card{background:#fff;border:1px solid var(--line);border-radius:14px;padding:18px 20px;margin:14px 0}
.hero{display:grid;grid-template-columns:1fr 300px;gap:18px;align-items:center}
.path{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.path ul{margin:0;padding-left:18px} .path .soon{color:var(--muted)}
.big{border-left:6px solid var(--orange)} .big p{margin:6px 0}
svg.fig{width:100%;max-width:300px;height:auto;display:block}
dl.vocab{display:grid;grid-template-columns:max-content 1fr;gap:6px 16px;margin:0}
dl.vocab dt{font-weight:800;color:var(--teal)} dl.vocab dd{margin:0}
table.grid{border-collapse:collapse;width:100%;font-size:16px}
table.grid th,table.grid td{border-bottom:1px solid var(--line);padding:8px 6px;text-align:left;vertical-align:top}
table.grid th{color:var(--teal);font-size:14px;text-transform:uppercase;letter-spacing:.04em}
.ex-grid{display:grid;grid-template-columns:1fr 260px;gap:16px;align-items:start}
.ex-grid.nofig{grid-template-columns:1fr}
.steps li{margin:4px 0}
.mistake{border-left:6px solid var(--bad)} .mistake p{margin:6px 0}
ol.qs{padding-left:22px}
.q{background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:10px 0}
.prompt{font-weight:700}
.qfig svg.fig{max-width:240px;margin-top:6px}
svg.fig.wide{max-width:420px}.qfig svg.fig.wide{max-width:400px}
.wtag{font-size:12px;font-weight:800;color:var(--teal);background:#e7f2f2;border-radius:999px;padding:2px 8px;white-space:nowrap}
.rel{margin:6px 0}
table.xy{border-collapse:collapse;font-family:"Space Mono",monospace;margin:8px 0}
table.xy td,table.xy th{border:1px solid var(--line);padding:3px 12px;text-align:center} table.xy th{background:#f3efe8}
svg.map{width:240px;max-width:100%}
ul.opts{list-style:none;padding:0;margin:6px 0}
.showbtn{font:inherit;font-weight:800;background:var(--orange);color:#fff;border:0;border-radius:999px;padding:10px 18px;cursor:pointer}
ol.ans li{margin:8px 0} ol.ans b{color:var(--good)}
h3.tier{margin:26px 0 4px;color:var(--navy);font-size:19px} h3.tier .tnum{display:inline-block;background:var(--navy);color:#fff;border-radius:999px;padding:1px 10px;font-size:13px;margin-right:6px;vertical-align:2px}
h3.tier .tsub{display:block;font-size:14px;font-weight:600;color:var(--muted)}
.wtag.stretch{color:#9a3412;background:#fdebe2}
.cta{background:var(--navy);color:#fff;border-radius:16px;padding:22px;margin:38px 0}
.cta h2{color:#fff;margin-top:0}
.cta a{display:inline-block;text-decoration:none;font-weight:800;padding:10px 16px;border-radius:999px;margin:4px 8px 0 0}
.cta .primary{background:var(--orange);color:#fff} .cta .secondary{background:#fff;color:var(--navy)}
footer{color:var(--muted);font-size:14px;padding:12px 0 40px}
/* ---- navigation (search, home browse, unit strip, previous/next) ---- */
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.js-only{display:none} html.js .js-only{display:flex} html.js .nojs{display:none}
header.top .wrap{flex-wrap:wrap}
.top-search{flex:1 1 220px;max-width:380px}
.search{position:relative}
.search input{width:100%;font:inherit;font-size:16px;color:var(--navy);background:#fff;border:2px solid #fff;border-radius:12px;padding:9px 14px;min-height:44px}
.search input:focus{outline:3px solid var(--orange);outline-offset:1px}
.results{position:absolute;z-index:20;left:0;right:0;top:calc(100% + 6px);list-style:none;margin:0;padding:0;background:#fff;border:1px solid var(--line);border-radius:12px;box-shadow:0 10px 30px rgba(11,44,60,.15);overflow:hidden;text-align:left}
.results li{border-bottom:1px solid #efe9e0} .results li:last-child{border-bottom:0}
.results a{display:flex;flex-wrap:wrap;align-items:baseline;gap:4px 10px;padding:11px 14px;text-decoration:none;color:var(--navy)}
.results li.on a,.results a:hover{background:#f3efe8}
.results .rt{font-weight:800}
.results .rp{font-size:13px;font-weight:700;color:var(--teal);background:#e3f0f2;border-radius:999px;padding:1px 9px}
.results .ra{font-size:14px;color:var(--muted)}
.results li.none{padding:12px 14px;color:#3e5560}
.results li.none a{display:inline;padding:0;color:var(--blue);text-decoration:underline;font-weight:700}
.wrap.wide{max-width:1080px}
.home-hero{max-width:760px;margin:40px 0 8px}
.home-hero h1{font-size:44px;font-weight:900;margin:0 0 10px}
.big-search{margin-top:14px}
.big-search input{font-size:19px;border:2px solid var(--navy);border-radius:16px;padding:16px 18px;min-height:60px;box-shadow:0 6px 0 rgba(11,44,60,.08)}
.chips{flex-wrap:wrap;align-items:center;gap:8px;margin-top:12px}
.chips span{font-size:14px;font-weight:700;color:var(--muted)}
.chip{font:inherit;font-size:14px;font-weight:700;color:var(--navy);background:#fff;border:1.5px solid #d9d2c7;border-radius:999px;padding:9px 14px;min-height:44px;cursor:pointer}
.chip:hover{border-color:var(--navy)}
.browse-head{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:14px;margin:48px 0 14px}
.browse-head h2{margin:0}
.gtabs{gap:6px;background:#efe9e0;border-radius:999px;padding:5px}
.gtabs button{font:inherit;font-size:15px;font-weight:800;color:var(--navy);background:transparent;border:0;border-radius:999px;padding:9px 18px;min-height:44px;cursor:pointer}
.gtabs button[aria-selected=true]{background:var(--navy);color:#fff}
.scards{flex-wrap:wrap;gap:12px;margin-bottom:14px}
.scard{font:inherit;text-align:left;flex:1 1 180px;display:flex;flex-direction:column;gap:4px;padding:16px 18px;min-height:84px;border-radius:16px;background:#fff;color:var(--navy);border:2px solid #d9d2c7;cursor:pointer}
.scard b{font-size:17px;font-weight:900} .scard span{font-size:14px;font-weight:700;color:var(--teal)}
.scard[aria-pressed=true]{background:var(--navy);color:#fff;border-color:var(--navy)} .scard[aria-pressed=true] span{color:#ffd9c7}
.scard.soon{cursor:default;background:#f7f4ef} .scard.soon span{color:var(--muted)}
.strand-panel{padding:24px} .strand-panel h3{font-size:22px;color:var(--navy);margin:0 0 14px}
.strand-panel h3 span{font-size:15px;font-weight:600;color:var(--muted);margin-left:8px}
.units{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:20px 28px}
.unit h4{display:flex;align-items:center;gap:8px;margin:0 0 6px;font-size:17px;color:var(--navy)}
.unum{font-family:"Space Mono",monospace;font-size:12px;font-weight:700;color:#fff;background:var(--teal);border-radius:6px;padding:2px 8px}
.unit ol{margin:0;padding-left:22px} .unit li{margin:4px 0} .unit a{font-weight:700;text-decoration:none}
.soonbox{color:#3e5560}
.unitstrip{display:flex;flex-wrap:wrap;align-items:center;gap:8px 10px;background:#fff;border:1px solid var(--line);border-radius:14px;padding:10px 14px;margin:8px 0 14px;font-size:15px}
.unitstrip .upos{color:var(--muted);font-size:14px} .unitstrip .ugap{flex:1 1 10px}
.uchip{font-size:14px;font-weight:700;border-radius:999px;padding:6px 12px;text-decoration:none;color:var(--navy);background:#efe9e0}
.uchip.on{background:var(--navy);color:#fff}
.stuck{display:flex;flex-wrap:wrap;align-items:center;gap:8px 10px;background:#fff1ea;border:1.5px solid #f7c3a8;border-radius:14px;padding:12px 16px;margin:16px 0}
.stuck b{color:#8a3200}
.stuck a{font-size:15px;font-weight:700;color:var(--navy);background:#fff;border:1.5px solid #f7c3a8;border-radius:999px;padding:7px 13px;text-decoration:none}
.prevnext{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:12px;margin:34px 0 0}
.pn{display:flex;flex-direction:column;gap:3px;padding:16px 18px;border-radius:16px;text-decoration:none;background:#fff;border:2px solid #d9d2c7;color:var(--navy)}
.pn span{font-size:13px;font-weight:800;color:var(--muted)} .pn b{font-size:17px}
.pn.next{background:var(--navy);border-color:var(--navy);color:#fff;text-align:right;align-items:flex-end} .pn.next span{color:#ffd9c7}
@media (max-width:640px){.home-hero h1{font-size:34px}.top-search{order:3;max-width:none;flex-basis:100%}}
/* transversal explorer */
.explore{display:grid;grid-template-columns:320px 1fr;gap:18px}
.chips{display:flex;flex-wrap:wrap;gap:8px;margin:8px 0}
.chips button{font:inherit;font-size:14px;font-weight:700;border:1px solid var(--line);background:#fff;color:var(--navy);border-radius:999px;padding:6px 12px;cursor:pointer}
.chips button[aria-pressed="true"]{background:var(--navy);color:#fff;border-color:var(--navy)}
input[type=range]{width:100%}
.meas{display:grid;grid-template-columns:repeat(4,1fr);gap:6px;margin-top:10px}
.meas div{background:var(--cream);border-radius:8px;padding:6px;text-align:center;font-family:"Space Mono",monospace;font-size:14px}
.meas div.on{background:var(--orange);color:#fff}
#exNote{font-weight:700;color:var(--navy);min-height:3em}
@media (max-width:680px){
  .hero,.path,.explore,.ex-grid{grid-template-columns:1fr} h1{font-size:28px}
  .card{padding:14px 12px} table.grid{font-size:14px} table.grid th,table.grid td{padding:6px 3px} table.grid th{font-size:12px}
  dl.vocab{grid-template-columns:1fr} dl.vocab dd{margin-bottom:8px}
  .strand ul{columns:1} .top-links a:not(.pill):not(.keep){display:none}
}
/* ---- formulas (/formulas/ and one page per topic) ---- */
.top-links a[aria-current=page]{text-decoration:underline;text-decoration-color:var(--orange);text-decoration-thickness:3px;text-underline-offset:6px}
.ftabs{display:none;flex-wrap:wrap;max-width:100%;margin-bottom:14px;border-radius:24px}
html.js .ftabs{display:flex}
.ftabs button{white-space:nowrap;flex:0 0 auto}
.fpanel h3 span{white-space:nowrap}
.fcard h4{font-family:"Space Mono",monospace;font-size:13px;text-transform:uppercase;letter-spacing:.06em;color:var(--teal)}
.fcard ul{margin:0;padding-left:0;list-style:none} .fcard li{margin:5px 0}
.ftags{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 14px}
.ftag{font-family:"Space Mono",monospace;font-size:12px;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--teal);background:#e3f0f2;border-radius:6px;padding:3px 9px;text-decoration:none}
.fstrip{margin-top:4px}
.fjump{display:flex;flex-wrap:wrap;gap:6px 14px;font-size:15px;margin:6px 0 0}
.fgroup h2{scroll-margin-top:16px}
.frows{background:#fff;border:1px solid var(--line);border-radius:14px}
.frow{display:grid;grid-template-columns:minmax(150px,230px) minmax(0,1fr) auto;gap:6px 18px;align-items:center;padding:14px 18px;border-bottom:1px solid var(--line)}
.frow:last-child{border-bottom:0}
.fname{font-weight:800;color:var(--navy);font-size:16px}
.fmath{font-size:21px;color:#0b1a22;min-width:0;overflow-x:auto;padding:2px 0}
.fmath math{display:inline math;font-family:"STIX Two Math","Cambria Math","Latin Modern Math","Times New Roman",serif}
.fcond{font-family:"Space Mono",monospace;font-size:12px;color:var(--muted);max-width:220px}
@media (max-width:680px){html.js .ftabs{flex-wrap:nowrap;overflow-x:auto;border-radius:999px}.frow{grid-template-columns:minmax(0,1fr);padding:12px 14px}.fcond{max-width:none}.fmath{font-size:19px}}
/* batch I: two-way tables as real tables */
.twoway-wrap{overflow-x:auto;margin-top:6px;max-width:100%}
table.twoway{border-collapse:collapse;font-size:.92rem;min-width:240px;margin:0 0 6px}
table.twoway caption{text-align:left;font-weight:700;padding:2px 0 4px}
table.twoway th,table.twoway td{border:1px solid #d9d2c6;padding:5px 9px;text-align:center}
table.twoway thead th,table.twoway tr:first-child th{background:#0B2C3C;color:#fff;font-weight:700}
table.twoway th[scope=row]{background:#f3eee6;text-align:left}
table.twoway .tot,table.twoway tr.tot td{font-weight:700;background:#faf7f2}