:root{--navy:#0f2a4a;--navy-dark:#0a1f38;--blue:#1d6fd1;--blue-dark:#155aab;--blue-light:#e8f1fc;--bg:#f4f6f8;--card:#fff;--text:#1a2332;--muted:#5b6b7f;--border:#e3e8ef;--green:#1a7f4b;--green-light:#e3f4ea;--amber:#8a6100;--amber-light:#fdf3d7;--radius:12px}*{box-sizing:border-box}html,body{margin:0;padding:0}body{background:var(--bg);color:var(--text);-webkit-text-size-adjust:100%;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;line-height:1.55}a{color:var(--blue);text-decoration:none}a:hover{text-decoration:underline}button{font:inherit;cursor:pointer}input{font:inherit}h1,h2,h3{color:var(--navy);line-height:1.25}h1{margin:0 0 .5rem;font-size:1.7rem}h2{margin:1.75rem 0 .75rem;font-size:1.3rem}h3{margin:1.25rem 0 .5rem;font-size:1.05rem}p{margin:0 0 .75rem}ul,ol{margin:0 0 .75rem;padding-left:1.4rem}li{margin-bottom:.35rem}.site-header{z-index:10;background:var(--navy);color:#fff;position:sticky;top:0;box-shadow:0 1px 6px #0a1f3859}.header-inner{align-items:center;gap:12px;max-width:1080px;min-height:54px;margin:0 auto;padding:0 16px;display:flex}.brand{color:#fff;white-space:nowrap;font-size:1.15rem;font-weight:800}.brand:hover{text-decoration:none}.header-search{color:#fff;background:#ffffff1f;border:1px solid #ffffff59;border-radius:999px;outline:none;flex:1;min-width:120px;max-width:420px;padding:7px 12px}.header-search::placeholder{color:#ffffffa6}.header-search:focus{background:#fff3;border-color:#fff}.lang-toggle{border:1px solid #fff6;border-radius:999px;flex-shrink:0;display:flex;overflow:hidden}.lang-toggle button{color:#fff;background:0 0;border:0;padding:6px 12px;font-size:.85rem}.lang-toggle button.active{color:var(--navy);background:#fff;font-weight:700}.main-nav{background:var(--navy-dark)}.main-nav .nav-inner{scrollbar-width:none;gap:4px;max-width:1080px;margin:0 auto;padding:0 16px;display:flex;overflow-x:auto}.main-nav a{color:#ffffffd9;white-space:nowrap;border-bottom:2px solid #0000;padding:9px 12px;font-size:.92rem}.main-nav a:hover{color:#fff;text-decoration:none}.main-nav a.active{color:#fff;border-bottom-color:var(--blue);font-weight:600}.page{max-width:1080px;margin:0 auto;padding:20px 16px 48px}.narrow{max-width:780px}.hero{background:var(--navy);color:#fff;border-radius:var(--radius);margin-bottom:24px;padding:28px 24px}.hero h1{color:#fff;font-size:1.9rem}.hero p{color:#ffffffd9;max-width:640px}.stats{flex-wrap:wrap;gap:10px;margin-top:18px;display:flex}.stat{text-align:center;background:#ffffff1a;border:1px solid #fff3;border-radius:10px;padding:8px 14px}.stat b{font-size:1.25rem;display:block}.stat span{color:#ffffffbf;font-size:.8rem}.section-head{justify-content:space-between;align-items:baseline;gap:12px;display:flex}.card-grid{grid-template-columns:1fr;gap:14px;display:grid}.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);color:var(--text);padding:16px;display:block}a.card:hover{border-color:var(--blue);text-decoration:none;box-shadow:0 2px 10px #0f2a4a14}.card h3{margin:0 0 6px;font-size:1.05rem}.card p{color:var(--muted);margin:0;font-size:.92rem}.card-icon{margin-bottom:8px;font-size:1.6rem;line-height:1}.meta{color:var(--muted);flex-wrap:wrap;gap:8px;margin-top:10px;font-size:.8rem;display:flex}.badge{border-radius:999px;padding:2px 9px;font-size:.78rem;font-weight:600;display:inline-block}.badge-beginner{background:var(--green-light);color:var(--green)}.badge-intermediate{background:var(--amber-light);color:var(--amber)}.badge-navy{background:var(--blue-light);color:var(--blue-dark)}.badge-grey{color:var(--muted);background:#eef1f4}.article-meta{color:var(--muted);flex-wrap:wrap;align-items:center;gap:8px;margin:8px 0 16px;font-size:.9rem;display:flex}.lead{color:#2c3a4d;font-size:1.08rem}.callout{background:var(--blue-light);border-left:4px solid var(--blue);border-radius:8px;margin:16px 0;padding:12px 16px}.callout.warn{background:var(--amber-light);border-left-color:var(--amber)}.callout p{margin:0}.source-note{color:var(--muted);border-top:1px solid var(--border);margin-top:24px;padding-top:12px;font-size:.85rem}.quiz-link{background:var(--blue);color:#fff;border-radius:999px;margin-top:16px;padding:10px 18px;font-weight:600;display:inline-block}.quiz-link:hover{background:var(--blue-dark);text-decoration:none}.question{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);margin-bottom:14px;padding:16px}.question h3{margin-top:0}.option{border:1px solid var(--border);cursor:pointer;background:#fff;border-radius:8px;align-items:flex-start;gap:10px;margin-bottom:8px;padding:10px 12px;display:flex}.option:hover{border-color:var(--blue)}.option input{accent-color:var(--blue);margin-top:3px}.option.selected{border-color:var(--blue);background:var(--blue-light)}.note{background:var(--amber-light);border:1px solid #f0d48a;border-radius:8px;margin:16px 0;padding:12px 16px;font-size:.92rem}details.outcome{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);margin-top:20px;padding:14px 16px}details.outcome summary{cursor:pointer;color:var(--navy);font-weight:700}.search-box{border:1px solid var(--border);background:#fff;border-radius:10px;width:100%;margin-bottom:16px;padding:11px 14px}.term{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);margin-bottom:10px;padding:14px 16px}.term h3{margin:0 0 4px}.term p{color:var(--muted);margin:0}.term .cat{color:var(--blue-dark);font-size:.8rem;font-weight:600}.learn-section{margin-bottom:28px}.learn-row{background:var(--card);border:1px solid var(--border);border-radius:10px;justify-content:space-between;align-items:center;gap:12px;margin-bottom:8px;padding:12px 16px;display:flex}.empty{color:var(--muted)}.site-footer{background:var(--navy);color:#ffffffd9;margin-top:24px}.footer-inner{max-width:1080px;margin:0 auto;padding:28px 16px}.footer-inner h3{color:#fff;margin-top:0}.newsletter{gap:8px;max-width:480px;margin:12px 0 20px;display:flex}.newsletter input{color:#fff;background:#ffffff1f;border:1px solid #ffffff59;border-radius:8px;flex:1;min-width:0;padding:10px 12px}.newsletter input::placeholder{color:#fff9}.newsletter button{color:var(--navy);background:#fff;border:0;border-radius:8px;padding:10px 18px;font-weight:700}.newsletter-msg{color:#bfe3c9;font-size:.9rem}.disclaimer{color:#ffffffa6;font-size:.85rem}.loading,.error-box{text-align:center;color:var(--muted);padding:48px 16px}.error-box button{background:var(--blue);color:#fff;border:0;border-radius:999px;margin-top:12px;padding:9px 18px}.back-link{margin-bottom:12px;font-size:.9rem;display:inline-block}@media (width<=639px){.header-inner{flex-wrap:wrap;row-gap:8px;padding-top:8px;padding-bottom:8px}.header-search{flex-basis:100%;order:3;max-width:none}.brand{font-size:1.05rem}}@media (width>=640px){.card-grid{grid-template-columns:repeat(2,1fr)}h1{font-size:2rem}.hero h1{font-size:2.2rem}}@media (width>=1024px){.card-grid{grid-template-columns:repeat(3,1fr)}.page{padding:28px 24px 64px}}.btn-row{flex-wrap:wrap;gap:8px;margin:12px 0;display:flex}.btn{color:var(--navy);border:1px solid var(--border);background:#fff;border-radius:999px;padding:8px 16px;font-size:.9rem;font-weight:600}.btn:hover{border-color:var(--blue)}.btn:disabled{opacity:.5;cursor:default}.btn-active{background:var(--navy);color:#fff;border-color:var(--navy)}.btn-primary{background:var(--blue);color:#fff;border:1px solid var(--blue);margin-top:12px}.btn-primary:hover{background:var(--blue-dark)}.calc-grid{grid-template-columns:1fr;gap:14px;display:grid}.calc-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:18px}.calc-card h3{margin-top:0}.formula{color:var(--navy);font-weight:600}.calc-note{color:var(--muted);font-size:.88rem}.fields{grid-template-columns:1fr 1fr;gap:10px;margin:12px 0;display:grid}.field{color:var(--muted);font-size:.88rem;display:block}.field input{border:1px solid var(--border);width:100%;color:var(--text);background:#fff;border-radius:8px;margin-top:4px;padding:9px 10px;display:block}.result-box{background:var(--blue-light);color:var(--navy);border-radius:8px;margin:12px 0;padding:12px 14px;font-weight:600}.option-row{flex-wrap:wrap;gap:8px;margin:12px 0;display:flex}.option-row .option{margin-bottom:0}.option-correct{border-color:var(--green);background:var(--green-light)}.option-wrong{background:#fdecea;border-color:#b3261e}.option-feedback{color:var(--muted);margin-top:4px;font-size:.88rem;display:block}.feedback{background:var(--blue-light);border-radius:8px;margin-top:12px;padding:12px 14px}.step-summary{background:var(--card);border:1px solid var(--border);color:var(--muted);border-radius:8px;margin-bottom:8px;padding:8px 14px;font-size:.9rem}@media (width>=640px){.calc-grid{grid-template-columns:repeat(2,1fr)}}