:root{--bg:#07070d;--bg-glow-1:#8b5cf624;--bg-glow-2:#22d3ee17;--surface:#0e0e18;--surface-2:#14141f;--surface-hover:#1a1a28;--border:#23233a;--border-strong:#33334f;--text:#e9e9f2;--text-dim:#a2a2b8;--text-faint:#8c8ca3;--accent:#a78bfa;--accent-strong:#7c3aed;--accent-soft:#a78bfa24;--cyan:#22d3ee;--beginner:#4ade80;--intermediate:#38bdf8;--advanced:#c084fc;--danger:#f87171;--paid:#fbbf24;--radius:14px;--radius-sm:9px;--shadow:0 10px 40px #0006;--maxw:1120px;--font:ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;--mono:ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace}[data-theme=light]{--bg:#fbfbfd;--bg-glow-1:#8b5cf61a;--bg-glow-2:#22d3ee14;--surface:#fff;--surface-2:#f4f4f8;--surface-hover:#eeeef4;--border:#e2e2ec;--border-strong:#c9c9d8;--text:#16161f;--text-dim:#56566b;--text-faint:#6c6c80;--accent:#7c3aed;--accent-strong:#6d28d9;--accent-soft:#7c3aed1a;--cyan:#0e7490;--beginner:#087a36;--intermediate:#0369a1;--advanced:#7e22ce;--danger:#b91c1c;--paid:#92400e;--shadow:0 8px 30px #14142d14}*{box-sizing:border-box}html{scroll-behavior:smooth}body{background:var(--bg);color:var(--text);font-family:var(--font);-webkit-font-smoothing:antialiased;min-height:100vh;margin:0;font-size:16px;line-height:1.6}body:before{content:"";pointer-events:none;z-index:0;background:radial-gradient(60rem 40rem at 15% -10%, var(--bg-glow-1), transparent 60%), radial-gradient(50rem 35rem at 90% 0%, var(--bg-glow-2), transparent 60%);position:fixed;inset:0}#root{z-index:1;position:relative}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}h1,h2,h3,h4{letter-spacing:-.02em;margin:0 0 .5em;font-weight:650;line-height:1.2}p{margin:0 0 1em}button{font:inherit;cursor:pointer}:focus-visible{outline:2px solid var(--accent);outline-offset:2px;border-radius:4px}.sr-only{clip:rect(0, 0, 0, 0);white-space:nowrap;border:0;width:1px;height:1px;margin:-1px;padding:0;position:absolute;overflow:hidden}.wrap{max-width:var(--maxw);margin:0 auto;padding:0 20px}.skip-link{background:var(--accent);color:#fff;z-index:100;border-radius:0 0 8px;padding:10px 16px;position:absolute;top:0;left:-9999px}.skip-link:focus{left:0}.nav{z-index:50;-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px);background:color-mix(in srgb, var(--bg) 82%, transparent);border-bottom:1px solid var(--border);position:sticky;top:0}.nav-inner{max-width:var(--maxw);flex-wrap:wrap;align-items:center;gap:8px;margin:0 auto;padding:12px 20px;display:flex}.brand{color:var(--text);letter-spacing:-.02em;align-items:center;gap:10px;margin-right:auto;font-size:1.05rem;font-weight:700;display:flex}.brand:hover{text-decoration:none}.brand-mark{flex:none;width:26px;height:26px}.nav-link{color:var(--text-dim);white-space:nowrap;border-radius:999px;padding:7px 12px;font-size:.9rem;font-weight:500}.nav-link:hover{background:var(--surface-hover);color:var(--text);text-decoration:none}.nav-link.active{background:var(--accent-soft);color:var(--accent)}.theme-toggle{border:1px solid var(--border);color:var(--text-dim);background:0 0;border-radius:999px;flex:none;place-items:center;width:34px;height:34px;font-size:.95rem;display:grid}.theme-toggle:hover{background:var(--surface-hover);color:var(--text)}.hero{text-align:center;padding:72px 0 44px}.hero h1{background:linear-gradient(120deg, var(--text) 30%, var(--accent) 70%, var(--cyan));color:#0000;-webkit-background-clip:text;background-clip:text;margin-bottom:18px;font-size:clamp(2.1rem,5.5vw,3.5rem)}.hero-sub{color:var(--text-dim);max-width:660px;margin:0 auto 30px;font-size:clamp(1rem,2.2vw,1.2rem)}.hero-stats{color:var(--text-faint);flex-wrap:wrap;justify-content:center;gap:26px;margin-top:26px;font-size:.85rem;display:flex}.hero-stats b{color:var(--text);font-variant-numeric:tabular-nums}.searchbar-wrap{max-width:620px;margin:0 auto;position:relative}.searchbar{background:var(--surface);border:1px solid var(--border-strong);max-width:620px;box-shadow:var(--shadow);border-radius:999px;align-items:center;gap:10px;margin:0 auto;padding:4px 6px 4px 18px;transition:border-color .15s;display:flex}.search-suggestions{z-index:60;background:var(--surface);border:1px solid var(--border-strong);border-radius:var(--radius);box-shadow:var(--shadow);gap:3px;padding:7px;display:grid;position:absolute;top:calc(100% - 10px);left:0;right:0}.search-suggestion{border-radius:var(--radius-sm);width:100%;color:var(--text);text-align:left;background:0 0;border:0;gap:2px;padding:10px 12px;display:grid}.search-suggestion:hover,.search-suggestion.active,.search-suggestion[aria-selected=true]{background:var(--accent-soft)}.search-suggestion>span{font-weight:650}.search-suggestion small{color:var(--text-dim);-webkit-line-clamp:2;line-clamp:2;-webkit-box-orient:vertical;line-height:1.35;display:-webkit-box;overflow:hidden}.searchbar:focus-within{border-color:var(--accent)}.searchbar input{color:var(--text);font:inherit;background:0 0;border:none;flex:1;min-width:0;padding:12px 0}.searchbar input:focus{outline:none}.searchbar input::placeholder{color:var(--text-faint)}.searchbar .go{background:var(--accent-strong);color:#fff;border:none;border-radius:999px;flex:none;padding:11px 20px;font-size:.9rem;font-weight:600}.searchbar .go:hover{filter:brightness(1.12)}.searchbar .clear{color:var(--text-faint);background:0 0;border:none;padding:4px 8px;font-size:1.1rem}.searchbar .clear:hover{color:var(--text)}.example-chips{flex-wrap:wrap;justify-content:center;gap:8px;margin-top:16px;display:flex}.example-chip{background:var(--surface-2);border:1px solid var(--border);color:var(--text-dim);border-radius:999px;padding:6px 13px;font-size:.82rem}.example-chip:hover{border-color:var(--accent);color:var(--accent)}section{padding:44px 0}.section-head{margin-bottom:24px}.section-head h2{margin-bottom:6px;font-size:clamp(1.4rem,3vw,1.9rem)}.section-head p{color:var(--text-dim);max-width:720px;margin:0}.eyebrow{text-transform:uppercase;letter-spacing:.11em;color:var(--accent);margin-bottom:8px;font-size:.75rem;font-weight:700}.level-accent{color:var(--lvl)}[data-level=beginner]{--lvl:var(--beginner)}[data-level=intermediate]{--lvl:var(--intermediate)}[data-level=advanced]{--lvl:var(--advanced)}.level-grid{grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:18px;display:grid}.level-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);color:var(--text);flex-direction:column;padding:24px;transition:transform .18s,border-color .18s;display:flex;position:relative;overflow:hidden}.level-card:hover{border-color:var(--lvl,var(--accent));text-decoration:none;transform:translateY(-3px)}.level-card:before{content:"";background:var(--lvl,var(--accent));height:3px;position:absolute;inset:0 0 auto}.level-card h3{margin-bottom:4px;font-size:1.3rem}.level-card .tagline{color:var(--lvl,var(--accent));margin-bottom:12px;font-size:.86rem;font-weight:600}.level-card p{color:var(--text-dim);flex:1;font-size:.92rem}.level-meta{color:var(--text-faint);border-top:1px solid var(--border);flex-wrap:wrap;gap:14px;margin-top:8px;padding-top:14px;font-size:.78rem;display:flex}.level-dot{background:var(--lvl);border-radius:50%;flex:none;width:9px;height:9px;display:inline-block}.resource-list{gap:12px;display:grid}.resource{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);grid-template-columns:1fr auto;gap:6px 16px;padding:18px 20px;transition:border-color .15s,background .15s;display:grid}.resource:hover{border-color:var(--border-strong);background:var(--surface-2)}.resource.is-done{opacity:.62}.resource-title{color:var(--text);align-items:baseline;gap:7px;font-size:1.02rem;font-weight:620;display:inline-flex}.resource-title:hover{color:var(--accent);text-decoration:none}.resource-title .ext{color:var(--text-faint);flex:none;font-size:.72rem}.resource-provider{color:var(--text-faint);margin-top:1px;font-size:.82rem}.resource-blurb{color:var(--text-dim);grid-column:1/-1;margin:6px 0 10px;font-size:.9rem}.resource-tags{flex-wrap:wrap;grid-column:1/-1;align-items:center;gap:7px;display:flex}.tag{border:1px solid var(--border);color:var(--text-dim);background:var(--surface-2);white-space:nowrap;border-radius:999px;padding:3px 9px;font-size:.72rem}.tag.level{border-color:color-mix(in srgb, var(--lvl) 45%, transparent);color:var(--lvl);background:color-mix(in srgb, var(--lvl) 12%, transparent);font-weight:600}.tag.free{color:var(--beginner);border-color:color-mix(in srgb, var(--beginner) 40%, transparent)}.tag.paid{color:var(--paid);border-color:color-mix(in srgb, var(--paid) 45%, transparent)}.tag.topic{cursor:pointer}.tag.topic:hover{border-color:var(--accent);color:var(--accent);text-decoration:none}.done-btn{border:1px solid var(--border);color:var(--text-faint);white-space:nowrap;background:0 0;border-radius:999px;flex:none;align-self:start;padding:5px 12px;font-size:.75rem}.done-btn:hover{border-color:var(--beginner);color:var(--beginner)}.done-btn.on{background:color-mix(in srgb, var(--beginner) 16%, transparent);border-color:var(--beginner);color:var(--beginner)}.topic-grid{grid-template-columns:repeat(auto-fill,minmax(268px,1fr));gap:12px;display:grid}.topic-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);color:var(--text);flex-direction:column;gap:6px;padding:16px 18px;transition:transform .15s,border-color .15s;display:flex}.topic-card:hover{border-color:var(--lvl,var(--accent));text-decoration:none;transform:translateY(-2px)}.topic-card h3{align-items:center;gap:8px;margin:0;font-size:1rem;display:flex}.topic-card p{color:var(--text-dim);margin:0;font-size:.85rem}.topic-card .count{color:var(--text-faint);margin-top:auto;padding-top:8px;font-size:.75rem}.topic-step{border:1px solid color-mix(in srgb, var(--lvl) 55%, var(--border));width:24px;height:24px;color:var(--lvl);background:color-mix(in srgb, var(--lvl) 10%, transparent);font-family:var(--mono);border-radius:50%;flex:none;place-items:center;font-size:.72rem;font-weight:700;display:inline-grid}.topic-header{border-bottom:1px solid var(--border);margin-bottom:26px;padding-bottom:26px}.topic-header h1{font-size:clamp(1.7rem,4vw,2.5rem)}.topic-oneliner{color:var(--text-dim);max-width:760px;font-size:1.08rem}.callout{background:var(--surface);border:1px solid var(--border);border-left:3px solid var(--accent);border-radius:var(--radius-sm);margin:18px 0;padding:16px 18px}.callout h4,.callout-title{text-transform:uppercase;letter-spacing:.09em;color:var(--accent);margin-bottom:6px;font-size:.75rem;font-weight:650}.callout p:last-child,.callout ul:last-child{margin-bottom:0}.callout ul{color:var(--text-dim);margin:0;padding-left:20px}.callout li{margin-bottom:4px}.two-col{grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:16px;display:grid}.prereq-row{flex-wrap:wrap;align-items:center;gap:8px;margin-bottom:16px;display:flex}.prereq-label{color:var(--text-faint);font-size:.8rem}.filters{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);flex-wrap:wrap;align-items:flex-start;gap:18px;margin-bottom:20px;padding:16px 18px;display:flex}.filter-group{flex-wrap:wrap;align-items:center;gap:7px;display:flex}.filter-group>span{text-transform:uppercase;letter-spacing:.07em;color:var(--text-faint);margin-right:2px;font-size:.75rem}.chip{background:var(--surface-2);border:1px solid var(--border);color:var(--text-dim);border-radius:999px;padding:5px 12px;font-size:.8rem}.chip:hover{border-color:var(--border-strong);color:var(--text)}.chip.on{background:var(--accent-soft);border-color:var(--accent);color:var(--accent);font-weight:600}.chip.reset{border-style:dashed;margin-left:auto}.result-count{color:var(--text-faint);margin-bottom:14px;font-size:.86rem}.empty{text-align:center;border:1px dashed var(--border-strong);border-radius:var(--radius);color:var(--text-dim);padding:48px 20px}.empty h3{color:var(--text)}.concept{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);margin-bottom:12px;overflow:hidden}.concept-anchor{scroll-margin-top:84px}.concept-head{text-align:left;width:100%;color:var(--text);background:0 0;border:none;align-items:center;gap:14px;padding:18px 20px;display:flex}.concept-head:hover{background:var(--surface-2)}.concept-head h3{flex:1;margin:0;font-size:1.02rem}.concept-head .caret{color:var(--text-faint);flex:none;transition:transform .2s}.concept.open .caret{transform:rotate(90deg)}.concept-body{border-top:1px solid var(--border);padding:18px 20px 20px}.concept-body p{color:var(--text-dim)}.concept-body .lead{color:var(--text)}.myth{grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:12px;margin:16px 0;display:grid}.myth>div{border-radius:var(--radius-sm);border:1px solid;padding:14px 16px;font-size:.9rem}.myth .wrong{background:#f8717112;border-color:#f8717147}.myth .right{background:#4ade8012;border-color:#4ade8047}.myth h5{text-transform:uppercase;letter-spacing:.09em;margin:0 0 6px;font-size:.72rem}.myth .wrong h5{color:var(--danger)}.myth .right h5{color:var(--beginner)}.myth p{color:var(--text-dim);margin:0}.demo{background:var(--surface-2);border:1px solid var(--border);border-radius:var(--radius-sm);margin:18px 0;padding:18px}.demo h5{text-transform:uppercase;letter-spacing:.09em;color:var(--cyan);margin:0 0 4px;font-size:.72rem}.demo-hint{color:var(--text-faint);margin:0 0 14px;font-size:.84rem}.demo input[type=range]{width:100%;accent-color:var(--accent);margin:6px 0 14px}.demo-readout{font-family:var(--mono);grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px;font-size:.86rem;display:grid}.demo-cell{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-sm);padding:10px 12px}.demo-cell .k{color:var(--text-faint);margin-bottom:3px;font-size:.72rem;display:block}.demo-cell .v{color:var(--text);font-variant-numeric:tabular-nums;font-size:1.05rem}.bar{background:var(--surface-hover);border-radius:999px;height:8px;margin-top:8px;overflow:hidden}.bar>i{background:linear-gradient(90deg, var(--accent), var(--cyan));height:100%;transition:width .12s;display:block}.demo-note{color:var(--text-dim);border-top:1px solid var(--border);margin:14px 0 0;padding-top:12px;font-size:.84rem}.quiz{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);max-width:780px;padding:26px}.quiz-progress{color:var(--text-faint);align-items:center;gap:12px;margin-bottom:18px;font-size:.8rem;display:flex}.quiz-progress .track{background:var(--surface-hover);border-radius:999px;flex:1;height:5px;overflow:hidden}.quiz-progress .track>i{background:var(--accent);height:100%;transition:width .25s;display:block}.quiz h3{margin-bottom:18px;font-size:1.2rem}.options{gap:9px;margin-bottom:18px;display:grid}.option{text-align:left;background:var(--surface-2);border:1px solid var(--border);color:var(--text);border-radius:var(--radius-sm);align-items:flex-start;gap:12px;padding:13px 16px;font-size:.94rem;transition:border-color .12s,background .12s;display:flex}.option:hover:not(:disabled){border-color:var(--accent);background:var(--surface-hover)}.option:disabled{cursor:default}.option .letter{font-family:var(--mono);color:var(--text-faint);flex:none;padding-top:2px;font-size:.82rem}.option.correct{border-color:var(--beginner);background:color-mix(in srgb, var(--beginner) 12%, transparent)}.option.correct .letter{color:var(--beginner)}.option.wrong{background:#f871711a;border-color:#f87171}.option.wrong .letter{color:var(--danger)}.explain{border-left:3px solid var(--accent);background:var(--surface-2);border-radius:var(--radius-sm);color:var(--text-dim);margin-bottom:18px;padding:14px 16px;font-size:.9rem}.explain strong{color:var(--text)}.btn{background:var(--accent-strong);color:#fff;border:none;border-radius:999px;padding:11px 22px;font-size:.92rem;font-weight:600}.btn:hover{filter:brightness(1.12)}.btn.ghost{border:1px solid var(--border-strong);color:var(--text-dim);background:0 0}.btn.ghost:hover{color:var(--text);border-color:var(--accent);filter:none}.btn-row{flex-wrap:wrap;align-items:center;gap:10px;display:flex}.score{text-align:center;padding:20px 0}.score .big{font-variant-numeric:tabular-nums;background:linear-gradient(120deg, var(--accent), var(--cyan));color:#0000;-webkit-background-clip:text;background-clip:text;font-size:3.2rem;font-weight:700}.review-item{border:1px solid var(--border);border-radius:var(--radius-sm);background:var(--surface-2);margin-bottom:10px;padding:14px 16px;font-size:.9rem}.review-item .q{color:var(--text);margin-bottom:6px;font-weight:600}.review-item .verdict{text-transform:uppercase;letter-spacing:.08em;font-size:.75rem;font-weight:700}.review-item.ok .verdict{color:var(--beginner)}.review-item.no .verdict{color:var(--danger)}.progress-banner{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);flex-wrap:wrap;align-items:center;gap:16px;margin-bottom:22px;padding:14px 18px;display:flex}.progress-banner .label{color:var(--text-dim);font-size:.85rem}.progress-banner .track{background:var(--surface-hover);border-radius:999px;flex:1;min-width:140px;height:7px;overflow:hidden}.progress-banner .track>i{background:linear-gradient(90deg, var(--beginner), var(--intermediate), var(--advanced));height:100%;transition:width .3s;display:block}.footer{border-top:1px solid var(--border);color:var(--text-faint);margin-top:50px;padding:34px 0 46px;font-size:.85rem}.footer-grid{grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:26px;margin-bottom:24px;display:grid}.footer h2{color:var(--text);text-transform:uppercase;letter-spacing:.09em;margin-bottom:10px;font-size:.8rem}.footer ul{gap:6px;margin:0;padding:0;list-style:none;display:grid}.footer a{color:var(--text-dim)}.legal-fineprint{color:var(--text-faint);margin:12px 0 0;font-size:.78rem;line-height:1.55}.route-loading{min-height:45vh;color:var(--text-dim);padding-top:64px}.breadcrumb{color:var(--text-faint);margin:26px 0 10px;font-size:.83rem}.breadcrumb a{color:var(--text-dim);text-underline-offset:2px;text-decoration:underline}@media (width<=640px){.hero{padding:48px 0 32px}.searchbar{padding-left:14px}.searchbar .go{padding:11px 15px}.resource{grid-template-columns:1fr}.done-btn{justify-self:start}.filters{flex-direction:column;gap:12px}.chip.reset{margin-left:0}.concept-anchor{scroll-margin-top:156px}}@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}html{scroll-behavior:auto}}