/* Learn pages (tools/build_seo_pages.py): base look + article layout. Loaded before lab.css. */
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,"Nirmala UI","Noto Sans Devanagari",sans-serif}
header{background:var(--panel);border-bottom:1px solid var(--line);display:flex;align-items:center;gap:16px;flex-wrap:wrap}
nav{display:flex;gap:4px;flex-wrap:wrap}
nav a{color:var(--muted);text-decoration:none;font-size:14px;padding:6px 10px;border-radius:6px}
nav a:hover{color:var(--ink)}
.spacer{flex:1}
.btn{border:1px solid var(--line);background:var(--panel);color:var(--ink);font:inherit;padding:6px 10px;border-radius:8px;cursor:pointer}
main{padding:0 24px 40px}
@media (max-width:600px){main{padding:0 16px 32px}.learn th,.learn td{padding:8px 8px}}
.learn{max-width:980px;margin:0 auto;padding:22px 0 40px}
.learn .crumbs{font-size:13px;color:var(--muted);margin:0 0 10px}.learn .crumbs a{color:var(--muted)}
.learn h1{font:700 clamp(26px,4vw,38px)/1.15 var(--f-head);margin:6px 0 10px;letter-spacing:-.01em}
.learn h2{font:700 20px var(--f-head);margin:26px 0 10px}
.learn p.lead{color:var(--muted);font-size:16px;line-height:1.6;margin:0 0 16px}
.learn .card{padding:18px 20px;margin:14px 0}
.learn table{width:100%;border-collapse:collapse;font-size:15px}
.learn th,.learn td{text-align:left;padding:10px 12px;border-bottom:1px solid var(--line);vertical-align:top}
.learn th{color:var(--muted);font-weight:600;font-size:13px;text-transform:uppercase;letter-spacing:.04em}
.learn tbody tr:nth-child(even){background:var(--soft)}
.learn td.f{font:16px/1.45 "Cambria Math","STIX Two Math",Cambria,Georgia,serif;overflow-wrap:anywhere}
.learn a.solve{white-space:nowrap;font-size:13px;font-weight:600;color:var(--accent);text-decoration:none}
.learn .sketch{display:block;max-width:300px;width:100%;margin:6px auto 0;background:#fff;border-radius:12px;padding:8px}
.learn .links{display:flex;flex-wrap:wrap;gap:8px;margin:8px 0}
.learn .links a{display:inline-block;padding:6px 12px;border:1px solid var(--line);border-radius:999px;text-decoration:none;color:var(--ink);font-size:14px;background:var(--panel)}
.learn .links a:hover{border-color:var(--accent);color:var(--accent)}
.learn .cta{display:inline-block;margin:6px 8px 6px 0;padding:10px 16px;border-radius:10px;font-weight:700;text-decoration:none;color:#fff;background:linear-gradient(120deg,var(--btn-a),var(--btn-b))}
.learn .big{font:700 clamp(22px,3.4vw,30px) var(--f-head);margin:4px 0}
.learn .grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(210px,1fr));gap:10px}
.learn .grid a{display:block;padding:10px 12px;border:1px solid var(--line);border-radius:12px;text-decoration:none;color:var(--ink);background:var(--panel)}
.learn .grid a small{display:block;color:var(--muted);font-size:12px}
.learn .lang-alt{float:right;font-size:14px}
.brand .bt{font:700 20px/1.15 var(--f-head);letter-spacing:-.01em;white-space:nowrap}