:root{--bg:#E6E9EC;--panel:#fff;--panel2:#F3F5F7;--ink:#22272D;--muted:#5B636C;--line:#CBD1D7;--accent:#FFC20E;--asphalt:#2B3036;--good:#1B7545;
 box-sizing:border-box;padding-top:env(safe-area-inset-top,0px);padding-bottom:env(safe-area-inset-bottom,0px)}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){--bg:#15181B;--panel:#1E2226;--panel2:#252A2F;--ink:#E9ECEF;--muted:#9BA4AE;--line:#353B42;--asphalt:#0F1214;--good:#4FC98A}}
*,*::before,*::after{box-sizing:inherit}
[hidden]{display:none!important}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.6 Barlow,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;-webkit-font-smoothing:antialiased}
:focus-visible{outline:3px solid var(--accent);outline-offset:2px}
a{color:inherit}
h1,h2,h3{font-family:"Barlow Condensed","Arial Narrow",Barlow,sans-serif;line-height:1.1;margin:0}
.skip{position:absolute;left:12px;top:-60px;background:var(--accent);color:#22272D;padding:10px 14px;border-radius:8px;font-weight:700;z-index:10;text-decoration:none}
.skip:focus{top:12px}
.sr-only{position:absolute!important;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

/* header */
.top{background:var(--asphalt);color:#F1F3F5;border-bottom:6px solid var(--accent)}
.top-in{max-width:860px;margin:0 auto;padding:14px 20px;display:flex;flex-wrap:wrap;gap:10px 16px;align-items:center;justify-content:space-between}
.brand{display:flex;align-items:center;gap:10px;color:#F1F3F5;text-decoration:none}
.brand svg{height:40px;width:auto;flex:none}
.brand b{font-family:"Barlow Condensed",sans-serif;font-size:1.55rem;line-height:1}
.brand span{color:#B9C1C9;font-weight:600;font-size:1rem;border-left:1px solid #57606A;padding-left:10px}
.top nav{display:flex;gap:8px;flex-wrap:wrap}
.top nav a{border:1px solid #57606A;border-radius:8px;padding:7px 12px;color:#F1F3F5;text-decoration:none;font-weight:600;font-size:.95rem;min-height:40px;display:inline-flex;align-items:center}
.top nav a.hi{background:var(--accent);border-color:var(--accent);color:#22272D}
.hero{max-width:860px;margin:0 auto;padding:24px 20px 4px}
.hero h1{font-size:clamp(2rem,6vw,2.9rem)}
.hero p{color:var(--muted);margin:6px 0 0;max-width:60ch}

main{max-width:860px;margin:0 auto;padding:8px 20px 40px}

/* search */
.search{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px;margin:16px 0}
.search label{display:block;font-weight:700;margin-bottom:6px}
.search .row{display:flex;gap:8px}
.search input{flex:1;min-width:0;border:1px solid var(--muted);background:var(--panel2);color:var(--ink);border-radius:8px;padding:10px 12px;min-height:46px;font:inherit}
.search button{border:0;background:var(--accent);color:#22272D;border-radius:8px;padding:0 16px;font:inherit;font-weight:700;cursor:pointer;min-height:46px}
.search .count{margin:8px 0 0;color:var(--muted);font-size:.92rem;min-height:1.4em}
.search.mini{padding:10px 12px;margin:14px 0 0}
.search.mini label{font-size:.92rem;margin-bottom:4px}

/* article cards on the index */
.cards{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:12px}
.cards a{display:flex;flex-direction:column;gap:4px;height:100%;background:var(--panel);border:1px solid var(--line);border-left:5px solid var(--accent);border-radius:12px;padding:14px 16px;text-decoration:none}
.cards a:hover{border-color:var(--muted);border-left-color:var(--accent)}
.cards h2{font-size:1.3rem}
.cards p{margin:0;color:var(--muted);font-size:.95rem}
.none{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:16px}
.none p{margin:0 0 6px}

/* articles */
.crumbs{font-size:.92rem;color:var(--muted);margin:14px 0 0}
.crumbs a{font-weight:600}
article{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:22px;margin-top:12px}
article h1{font-size:clamp(1.9rem,5.5vw,2.5rem);margin-bottom:6px}
article .lead{font-size:1.08rem;color:var(--muted);margin:0 0 6px;max-width:64ch}
article h2{font-size:1.45rem;margin:26px 0 8px;border-bottom:2px solid var(--accent);padding-bottom:3px}
article h3{font-size:1.2rem;margin:18px 0 6px}
article p,article li{max-width:68ch}
article ol,article ul{padding-left:24px;margin:8px 0}
article li{margin:6px 0}
article ol>li::marker{font-weight:700}
.ui{display:inline;background:var(--panel2);border:1px solid var(--line);border-radius:5px;padding:0 5px;font-weight:600;white-space:normal}
.tip{background:color-mix(in srgb,var(--accent) 16%,var(--panel));border-left:5px solid var(--accent);border-radius:0 8px 8px 0;padding:10px 14px;margin:14px 0}
.tip p{margin:0}
.tip p+p{margin-top:6px}
.math{background:var(--asphalt);color:#F1F3F5;border-radius:10px;padding:12px 14px;margin:12px 0;font-variant-numeric:tabular-nums}
.math p{margin:0}.math p+p{margin-top:4px}
.math b{color:var(--accent)}
.scroll{overflow-x:auto;-webkit-overflow-scrolling:touch}
table{border-collapse:collapse;width:100%;font-size:.95rem;margin:10px 0}
th,td{padding:8px 10px;border-bottom:1px solid var(--line);text-align:left;vertical-align:top}
th{background:var(--panel2);color:var(--muted);font-size:.88rem}
.related{margin-top:22px}
.related h2{font-size:1.25rem;border:0;margin:0 0 6px}
.related ul{list-style:none;padding:0;margin:0;display:flex;flex-wrap:wrap;gap:8px}
.related a{display:inline-block;border:1px solid var(--line);border-radius:20px;padding:5px 12px;text-decoration:none;font-weight:600;background:var(--panel2)}
.feedback{margin-top:18px;background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px 16px;display:flex;flex-wrap:wrap;gap:8px 14px;align-items:center}
.feedback p{margin:0;font-weight:700}
.feedback a{display:inline-flex;align-items:center;min-height:40px;border:1px solid var(--line);border-radius:8px;padding:6px 14px;font-weight:600;text-decoration:none;background:var(--panel2)}
.feedback small{flex-basis:100%;color:var(--muted);font-size:.88rem}
.contact{font-size:1.25rem;font-weight:700}

footer{max-width:860px;margin:0 auto;padding:0 20px 40px;color:var(--muted);font-size:.92rem;text-align:center}
footer a{font-weight:600}
@media (max-width:560px){ .brand span{display:none} article{padding:18px 16px} body{font-size:16.5px} }
@media (prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}