:root{--navy: #0f2144;--navy-soft: #475a7a;--blue: #2f80ed;--blue-dark: #1d63c7;--blue-light: #eaf3ff;--blue-border: #cfe2fb;--bg: #f6faff;--white: #ffffff;--red: #c0392b;--red-bg: #fdecea;--green: #1e7d4f;--green-bg: #e7f6ee;--radius: 16px;--shadow: 0 2px 6px rgba(15, 33, 68, .05), 0 8px 24px rgba(47, 128, 237, .08);--font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif}*,*:before,*:after{box-sizing:border-box}html{-webkit-text-size-adjust:100%}body{margin:0;font-family:var(--font);font-size:1rem;line-height:1.6;color:var(--navy);background:linear-gradient(180deg,#ffffff 0%,var(--bg) 380px) no-repeat,var(--bg);min-height:100vh}#root{min-height:100vh;display:flex;flex-direction:column}h1,h2,h3,h4{line-height:1.25;margin:0 0 .5rem}p{margin:0 0 .9rem}:focus-visible{outline:3px solid var(--blue);outline-offset:2px;border-radius:6px}.skip-link{position:absolute;left:-999px;top:8px;background:var(--navy);color:#fff;padding:8px 14px;border-radius:8px;z-index:100}.skip-link:focus{left:8px}.navbar{position:sticky;top:0;z-index:20;background:#fffffff2;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border-bottom:1px solid var(--blue-border)}.navbar-inner{max-width:1080px;margin:0 auto;padding:10px 16px;display:flex;align-items:center;justify-content:space-between;gap:12px}.brand{display:flex;align-items:center;gap:10px;background:none;border:0;padding:4px;font:inherit;font-weight:800;font-size:1.15rem;color:var(--navy);cursor:pointer}.brand-logo{display:grid;place-items:center;width:36px;height:36px;border-radius:10px;color:#fff;background:linear-gradient(135deg,#5aa2ff,var(--blue-dark))}.nav-desktop{display:none;gap:4px}.nav-link{background:none;border:0;font:inherit;font-weight:600;color:var(--navy-soft);padding:8px 14px;border-radius:10px;cursor:pointer}.nav-link:hover{background:var(--blue-light);color:var(--navy)}.nav-link.active{background:var(--blue-light);color:var(--blue-dark)}.menu-toggle{display:grid;place-items:center;width:44px;height:44px;background:var(--blue-light);border:0;border-radius:12px;color:var(--navy);cursor:pointer}.nav-mobile{display:flex;flex-direction:column;padding:4px 16px 14px;gap:4px;border-top:1px solid var(--blue-border);background:#fff}.nav-mobile .nav-link{text-align:left;padding:12px 14px;font-size:1.05rem}@media(min-width:860px){.nav-desktop{display:flex}.menu-toggle,.nav-mobile{display:none}}.container{width:100%;max-width:1080px;margin:0 auto;padding:24px 16px 48px;flex:1}.footer{text-align:center;color:var(--navy-soft);font-size:.9rem;padding:20px 16px 28px}.footer p{margin:0}.page-title{font-size:1.75rem}.page-sub{color:var(--navy-soft);margin-bottom:1.25rem}.hint{color:var(--navy-soft);font-size:.9rem}.card{background:var(--white);border:1px solid var(--blue-border);border-radius:var(--radius);box-shadow:var(--shadow);padding:20px;margin-bottom:20px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font:inherit;font-weight:700;border-radius:12px;border:1px solid transparent;padding:11px 20px;min-height:44px;cursor:pointer;text-decoration:none}.btn:disabled{opacity:.65;cursor:not-allowed}.btn-primary{background:linear-gradient(135deg,#4a97ff,var(--blue-dark));color:#fff;box-shadow:0 4px 12px #2f80ed4d}.btn-primary:hover:not(:disabled){filter:brightness(1.05)}.btn-secondary{background:#fff;color:var(--blue-dark);border-color:var(--blue)}.btn-secondary:hover:not(:disabled){background:var(--blue-light)}.btn-ghost{background:var(--blue-light);color:var(--navy);padding:8px 14px;min-height:40px}.btn-ghost:hover:not(:disabled){background:#d9eaff}.btn-danger{color:var(--red)}.btn-lg{padding:14px 28px;font-size:1.05rem}.hero{text-align:center;padding:40px 16px 36px;border-radius:24px;margin-bottom:24px;background:linear-gradient(135deg,#eaf3ff,#fff 60%,#dcecff);border:1px solid var(--blue-border)}.eyebrow{font-weight:800;letter-spacing:.18em;color:var(--blue-dark);font-size:.85rem;margin-bottom:10px}.hero h1{font-size:clamp(2rem,7vw,3.25rem);margin-bottom:14px}.hero-sub{max-width:620px;margin:0 auto 24px;color:var(--navy-soft);font-size:1.1rem}.hero-buttons{display:flex;flex-wrap:wrap;gap:12px;justify-content:center}.feature-grid{display:grid;grid-template-columns:1fr;gap:16px;margin-bottom:24px}.feature{display:flex;flex-direction:column;align-items:flex-start;gap:8px;text-align:left;font:inherit;color:inherit;cursor:pointer;margin-bottom:0}.feature:hover{border-color:var(--blue);transform:translateY(-2px);transition:transform .15s}.feature-icon{display:grid;place-items:center;width:46px;height:46px;border-radius:12px;background:var(--blue-light);color:var(--blue-dark)}.feature-title{font-weight:800;font-size:1.1rem}.feature-text{color:var(--navy-soft)}.built h2{font-size:1.3rem}.built p{margin:0;color:var(--navy-soft)}@media(min-width:600px){.feature-grid{grid-template-columns:repeat(2,1fr)}}@media(min-width:960px){.feature-grid{grid-template-columns:repeat(4,1fr)}}.field{display:flex;flex-direction:column;gap:6px;margin-bottom:16px;flex:1;min-width:0}.field label{font-weight:700}input[type=text],input[type=number],input[type=date],select,textarea{width:100%;font:inherit;color:var(--navy);background:#fff;border:1.5px solid #b9cbe6;border-radius:12px;padding:11px 14px;min-height:46px}textarea{resize:vertical}input:focus,select:focus,textarea:focus{border-color:var(--blue);outline:3px solid rgba(47,128,237,.25);outline-offset:0}.row{display:flex;flex-direction:column;gap:0 16px}@media(min-width:700px){.row{flex-direction:row}}.alert{border-radius:12px;padding:12px 14px;margin-bottom:16px;font-weight:600}.alert-error{background:var(--red-bg);color:var(--red);border:1px solid #f3c1bb}.alert-info{background:var(--blue-light);color:var(--navy);border:1px solid var(--blue-border)}.alert-success{background:var(--green-bg);color:var(--green);border:1px solid #b8e3cc}.result-head,.note-head{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:12px;margin-bottom:12px}.result-head h2,.note-head h2{margin:0;font-size:1.25rem;overflow-wrap:anywhere}.result-actions{display:flex;flex-wrap:wrap;gap:8px}.note-meta{color:var(--navy-soft);font-size:.9rem;margin:2px 0 0}.empty{text-align:center;color:var(--navy-soft)}.empty p{margin:0}.markdown{overflow-wrap:anywhere}.markdown h3{font-size:1.2rem;margin-top:1.2rem;color:var(--blue-dark)}.markdown h4{font-size:1.05rem;margin-top:1rem}.markdown h3:first-child,.markdown h4:first-child{margin-top:0}.markdown ul,.markdown ol{margin:0 0 .9rem;padding-left:1.4rem}.markdown li{margin-bottom:.35rem}.markdown code{background:var(--blue-light);padding:1px 6px;border-radius:6px;font-size:.95em}.markdown pre{background:#0f2144;color:#eaf3ff;padding:14px;border-radius:12px;overflow-x:auto;margin:0 0 .9rem}.markdown pre code{background:none;padding:0;color:inherit}.question{margin:0 0 16px;min-width:0}.question legend{font-weight:700;padding:0 6px;margin-bottom:4px}.qnum{display:inline-grid;place-items:center;width:28px;height:28px;border-radius:50%;background:var(--blue);color:#fff;font-size:.9rem;margin-right:6px}.question.right{border-color:#8fd3b0}.question.wrong{border-color:#f0b3ab}.option{display:flex;align-items:center;gap:10px;padding:12px 14px;margin-top:10px;cursor:pointer;border:1.5px solid var(--blue-border);border-radius:12px;background:#fff}.option:hover{background:var(--blue-light)}.option input{width:18px;height:18px;accent-color:var(--blue);flex:none}.option .letter{font-weight:800;color:var(--blue-dark);flex:none}.option-correct{background:var(--green-bg);border-color:#6cc597}.option-wrong{background:var(--red-bg);border-color:#e8a49b}.explain{margin-top:14px;padding:12px 14px;border-radius:12px;background:var(--blue-light)}.quiz-footer{display:flex;flex-wrap:wrap;align-items:center;gap:12px}.score{text-align:center}.score-big{font-size:2.6rem;font-weight:800;margin:0 0 8px;color:var(--blue-dark)}.score-big span{font-size:1.2rem;color:var(--navy-soft)}.score-stats,.score-actions{display:flex;flex-wrap:wrap;justify-content:center;gap:10px;margin-bottom:14px}.pill{display:inline-flex;align-items:center;gap:6px;padding:6px 14px;border-radius:999px;font-weight:700}.pill-good{background:var(--green-bg);color:var(--green)}.pill-bad{background:var(--red-bg);color:var(--red)}.fatal{max-width:480px;margin:20vh auto 0;text-align:center;padding:0 16px}@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}