@import"https://fonts.googleapis.com/css2?family=Instrument+Serif:ital@0;1&family=Plus+Jakarta+Sans:wght@400;500;600;700&display=swap";:root{font-family:Plus Jakarta Sans,sans-serif;color:#f8fafc;background:#070a12;font-synthesis:none;--bg: #070a12;--surface: #0d1220;--card: #111827;--raised: #172033;--text: #f8fafc;--secondary: #cbd5e1;--muted: #718096;--line: rgba(148, 163, 184, .16);--line-strong: rgba(148, 163, 184, .3);--cyan: #4fc3f7;--violet: #a78bfa;--green: #34d399;--danger: #fb7185;--radius: 18px;--shadow: 0 22px 70px rgba(0, 0, 0, .34)}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;min-width:320px;min-height:100vh;background-color:var(--bg);background-image:linear-gradient(rgba(79,195,247,.035) 1px,transparent 1px),linear-gradient(90deg,rgba(79,195,247,.035) 1px,transparent 1px);background-size:32px 32px;color:var(--text)}button,input{font:inherit}button{color:inherit}button,a{-webkit-tap-highlight-color:transparent}button:focus-visible,a:focus-visible,input:focus-visible{outline:2px solid var(--cyan);outline-offset:3px}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.topbar{position:sticky;top:0;z-index:30;height:68px;display:grid;grid-template-columns:auto auto minmax(220px,430px) auto;align-items:center;gap:clamp(20px,4vw,68px);padding:0 clamp(20px,3vw,46px);background:#070a12e0;border-bottom:1px solid var(--line);-webkit-backdrop-filter:blur(18px);backdrop-filter:blur(18px)}.brand{display:inline-flex;align-items:center;gap:11px;color:var(--text);text-decoration:none;font-size:20px;font-weight:700;letter-spacing:-.04em;white-space:nowrap}.brand svg{width:32px;height:32px;fill:none;stroke:var(--cyan);stroke-width:1.5}.brand b{color:var(--cyan);font-weight:600}.topbar>div{cursor:pointer}.topbar nav{display:flex;gap:30px;height:100%}.topbar nav button{position:relative;border:0;background:none;color:var(--secondary);cursor:pointer;padding:0}.topbar nav button.nav-active{color:var(--text)}.topbar nav button.nav-active:after{content:"";position:absolute;left:0;right:0;bottom:0;height:3px;border-radius:3px 3px 0 0;background:var(--cyan);box-shadow:0 0 18px #4fc3f78c}.searchbox{height:40px;border:1px solid var(--line-strong);border-radius:12px;display:flex;align-items:center;gap:10px;padding:0 14px;color:var(--muted);background:#0d12208c}.searchbox input{width:100%;border:0;outline:0;color:var(--text);background:transparent}.searchbox input::placeholder{color:#64748b}.studyvis-link{display:inline-flex;align-items:center;gap:2px;color:var(--secondary);text-decoration:none;font-size:13px;white-space:nowrap}.library-page{width:min(1320px,calc(100% - 48px));margin:0 auto}.library-intro{min-height:540px;display:grid;grid-template-columns:minmax(0,740px) 1fr;align-items:center;gap:80px;border-bottom:1px solid var(--line)}.chapter-context{display:inline-block;color:var(--cyan);font-size:12px;font-weight:700}.library-intro h1{margin:0 0 24px;max-width:780px;font-size:clamp(54px,7vw,96px);line-height:.92;letter-spacing:-.04em}.library-intro h1 em{font-family:"Instrument Serif",serif;color:var(--cyan);font-weight:400}.library-intro p{max-width:700px;color:var(--secondary);font-size:18px;line-height:1.8}.orbit-diagram{width:min(360px,30vw);aspect-ratio:1;position:relative;border:1px solid rgba(79,195,247,.34);border-radius:50%;animation:orbit 24s linear infinite}.orbit-diagram:before,.orbit-diagram:after{content:"";position:absolute;top:14%;right:14%;bottom:14%;left:14%;border:1px solid rgba(167,139,250,.38);border-radius:50%;transform:rotate(64deg)}.orbit-diagram:after{top:34%;right:34%;bottom:34%;left:34%;border-color:#34d3998c;transform:none}.orbit-diagram span{position:absolute;width:18px;height:18px;border-radius:50%;background:var(--cyan);box-shadow:0 0 30px var(--cyan)}.orbit-diagram span:nth-child(1){top:12%;left:50%}.orbit-diagram span:nth-child(2){bottom:18%;left:14%;background:var(--violet)}.orbit-diagram span:nth-child(3){right:6%;top:58%;background:var(--green)}.orbit-diagram i{position:absolute;top:42%;right:42%;bottom:42%;left:42%;display:grid;place-items:center;border-radius:50%;background:var(--raised);color:var(--text);font-style:normal;font-weight:700}@keyframes orbit{to{transform:rotate(360deg)}}.chapter-library{padding:90px 0 110px}.section-heading{display:flex;justify-content:space-between;align-items:end;margin-bottom:30px}.section-heading h2{margin:0;font-size:38px;letter-spacing:-.04em}.section-heading>span{color:var(--muted);font-size:13px}.chapter-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.chapter-card{position:relative;min-height:390px;overflow:hidden;text-align:left;border:1px solid var(--line);border-radius:22px;background:linear-gradient(150deg,color-mix(in srgb,var(--chapter-accent) 10%,var(--surface)),var(--surface) 44%);padding:28px;cursor:pointer;transition:transform .25s ease,border-color .25s ease,box-shadow .25s ease}.chapter-card:after{content:"";position:absolute;width:210px;height:210px;right:-80px;bottom:-90px;border:1px solid color-mix(in srgb,var(--chapter-accent) 50%,transparent);border-radius:50%;box-shadow:0 0 80px color-mix(in srgb,var(--chapter-accent) 18%,transparent)}.chapter-card:hover{transform:translateY(-7px);border-color:color-mix(in srgb,var(--chapter-accent) 65%,transparent);box-shadow:var(--shadow)}.chapter-number{display:block;color:var(--muted);font:500 12px/1 monospace;letter-spacing:.12em}.chapter-card-icon{display:grid;place-items:center;width:58px;height:58px;margin:54px 0 24px;border-radius:50%;color:var(--chapter-accent);border:1px solid color-mix(in srgb,var(--chapter-accent) 55%,transparent);background:color-mix(in srgb,var(--chapter-accent) 10%,transparent)}.chapter-card-icon svg{width:26px}.chapter-eyebrow{display:block;color:var(--chapter-accent);font-size:11px;text-transform:uppercase;letter-spacing:.12em}.chapter-card strong{display:block;margin-top:9px;font-size:25px;letter-spacing:-.035em}.chapter-summary{display:block;margin-top:12px;color:var(--secondary);font-size:14px;line-height:1.65}.chapter-enter{position:absolute;left:28px;bottom:26px;z-index:1;display:flex;align-items:center;gap:6px;color:var(--chapter-accent);font-size:13px;font-weight:700}.site-footer{display:flex;justify-content:space-between;padding:24px 0 36px;color:var(--muted);border-top:1px solid var(--line);font-size:12px}.chapter-page{width:min(1500px,calc(100% - 40px));margin:0 auto;padding-bottom:70px}.chapter-head{min-height:86px;display:grid;grid-template-columns:auto 1fr minmax(280px,400px) auto;gap:22px;align-items:center;border-bottom:1px solid var(--line)}.back-button,.ghost-button,.icon-button,.text-button{border:0;background:none;cursor:pointer}.back-button{display:flex;align-items:center;gap:7px;color:var(--secondary)}.breadcrumb{color:var(--muted);font-size:13px}.chapter-progress{display:grid;grid-template-columns:auto 1fr auto;gap:10px;align-items:center;color:var(--muted);font-size:11px;text-transform:uppercase;letter-spacing:.08em}.chapter-progress>div,.timeline{overflow:hidden;height:5px;border-radius:10px;background:#253149}.chapter-progress i,.timeline i{display:block;height:100%;border-radius:inherit;background:linear-gradient(90deg,var(--cyan),var(--chapter-accent));transition:width .35s ease}.chapter-progress b{color:var(--text)}.primary-button{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:0;border-radius:11px;min-height:42px;padding:0 20px;background:var(--cyan);color:#03111b;font-weight:700;cursor:pointer;box-shadow:0 8px 24px #4fc3f72e}.primary-button:disabled{opacity:.45;cursor:not-allowed}.primary-button.full{width:100%}.lens-tabs{width:360px;height:56px;display:grid;grid-template-columns:1fr 1fr;margin:18px auto;padding:5px;border:1px solid var(--line-strong);border-radius:999px;background:var(--surface)}.lens-tabs button{display:flex;align-items:center;justify-content:center;gap:8px;border:0;border-radius:inherit;background:transparent;color:var(--secondary);cursor:pointer}.lens-tabs button[aria-selected=true]{color:#04101b;background:var(--cyan);box-shadow:0 6px 20px #4fc3f73b;font-weight:700}.lesson-bench{display:grid;grid-template-columns:minmax(245px,.78fr) minmax(520px,1.8fr) minmax(235px,.72fr);min-height:665px;border:1px solid var(--line-strong);border-radius:22px;background:#0d1220c2;box-shadow:var(--shadow);overflow:hidden}.narrative-panel,.index-panel{padding:clamp(24px,2.3vw,38px);background:linear-gradient(180deg,#111827f0,#090e1af0)}.narrative-panel{border-right:1px solid var(--line)}.index-panel{border-left:1px solid var(--line)}.narrative-panel h1{margin:10px 0 12px;font-size:clamp(34px,3vw,52px);line-height:.98;letter-spacing:-.04em}.lead{color:var(--secondary);line-height:1.55;font-size:14px}.narrative-steps{position:relative;list-style:none;margin:30px 0 0;padding:0}.narrative-steps:before{content:"";position:absolute;top:19px;bottom:28px;left:15px;width:1px;background:var(--line-strong)}.narrative-steps li button{position:relative;width:100%;display:grid;grid-template-columns:32px 1fr;gap:13px;padding:0 0 23px;border:0;text-align:left;background:none;cursor:pointer}.narrative-steps li button>span{z-index:1;width:31px;height:31px;display:grid;place-items:center;border:1px solid var(--line-strong);border-radius:50%;color:var(--muted);background:var(--surface);font-size:11px}.narrative-steps li.active button>span{color:#04101b;border-color:var(--cyan);background:var(--cyan);box-shadow:0 0 20px #4fc3f759}.narrative-steps li.done button>span{color:var(--green);border-color:var(--green)}.narrative-steps strong{display:block;margin:3px 0 4px;color:var(--secondary);font-size:13px}.narrative-steps li.active strong{color:var(--text)}.narrative-steps p{margin:0;color:var(--muted);font-size:11px;line-height:1.5}.narrative-steps li:not(.active) p{display:none}.stage-panel{min-width:0;display:flex;flex-direction:column;background:#080e18}.stage-panel>header{height:52px;display:flex;align-items:center;justify-content:space-between;padding:0 20px;border-bottom:1px solid var(--line);color:var(--muted);font-size:11px;text-transform:uppercase;letter-spacing:.08em}.stage-panel>header div{display:flex;align-items:center;gap:8px;color:var(--secondary)}.live-dot{width:7px;height:7px;border-radius:50%;background:var(--green);box-shadow:0 0 12px var(--green)}.visual-stack{flex:1;display:flex;flex-direction:column;min-height:0}.model-svg{width:100%;flex:1;min-height:420px;display:block}.model-svg text{font-family:Plus Jakarta Sans,sans-serif}.svg-label{fill:#f8fafc;font-size:15px;font-weight:600}.svg-muted{fill:#94a3b8;font-size:12px}.svg-accent{fill:var(--cyan);font-size:13px;font-weight:600}.svg-violet{fill:var(--violet);font-size:13px;font-weight:600}.ray{fill:none;stroke-width:3;color:#e4f6ff;filter:url(#rayGlow)}.ray.incident{stroke:#d9f3ff}.ray.refracted{stroke:var(--violet);color:var(--violet)}.ray.reflected{stroke:#fb7185;color:#fb7185}.equation-row{min-height:64px;display:flex;align-items:center;justify-content:space-between;gap:20px;padding:0 22px;border-top:1px solid var(--line);color:var(--secondary);font-family:Georgia,serif;font-size:17px}.equation-row strong{color:var(--chapter-accent);font-family:Plus Jakarta Sans,sans-serif;font-size:15px}.particle{fill:#72e6c0;animation:drift 2.2s ease-in-out infinite alternate}.flow-arrow{fill:none;stroke:var(--cyan);stroke-width:3;color:var(--cyan);stroke-dasharray:8 7;animation:dash 1.5s linear infinite}@keyframes drift{to{transform:translate(12px,-7px)}}@keyframes dash{to{stroke-dashoffset:-30}}.trade-route{fill:none;stroke:#c69335;stroke-width:4;stroke-dasharray:7 9;transition:opacity .3s,stroke-width .3s}.trade-route.active{stroke:#f8c866;stroke-width:7;animation:dash 2s linear infinite}.trade-node circle{fill:#402f16;stroke:#9a7433;stroke-width:2}.trade-node text{fill:#cbd5e1;font-size:12px}.trade-node.active circle{fill:#f59e0b;stroke:#ffe4a3}.transport{height:68px;display:grid;grid-template-columns:auto auto 1fr auto;gap:13px;align-items:center;padding:0 18px;border-top:1px solid var(--line);color:var(--muted);font-size:11px}.transport-main,.icon-button{width:38px;height:38px;display:grid;place-items:center;border-radius:50%;border:1px solid var(--line-strong);background:var(--surface);cursor:pointer}.transport-main{color:#04101b;border:0;background:var(--cyan)}.transport svg{width:16px}.index-panel h2{margin:0 0 10px;font-size:24px;letter-spacing:-.035em}.index-panel>p{min-height:66px;margin:0;color:var(--secondary);font-size:13px;line-height:1.65}.objective{margin:24px 0;padding:16px;border:1px solid color-mix(in srgb,var(--chapter-accent) 45%,transparent);border-radius:14px;background:color-mix(in srgb,var(--chapter-accent) 8%,transparent)}.objective span{display:block;margin-bottom:7px;color:var(--chapter-accent);font-size:10px;text-transform:uppercase;letter-spacing:.1em}.objective strong{color:var(--secondary);font-size:12px;line-height:1.5}.index-panel nav{display:grid;gap:3px}.index-panel nav button{display:grid;grid-template-columns:25px 1fr;align-items:center;gap:8px;border:0;background:none;padding:8px 0;color:var(--muted);text-align:left;font-size:11px;cursor:pointer}.index-panel nav button span{width:23px;height:23px;display:grid;place-items:center;border:1px solid var(--line-strong);border-radius:50%;font-size:9px}.index-panel nav button.active{color:var(--text)}.index-panel nav button.active span{color:var(--chapter-accent);border-color:var(--chapter-accent)}.dock-wrap{display:grid;grid-template-rows:0fr;opacity:0;transition:grid-template-rows .42s cubic-bezier(.2,.8,.2,1),opacity .25s}.dock-wrap>*{overflow:hidden}.dock-wrap.open{grid-template-rows:1fr;opacity:1}.parameter-dock{margin-top:14px;padding:24px;border:1px solid var(--line-strong);border-radius:20px;background:#0d1220eb}.dock-title{display:flex;justify-content:space-between;align-items:start;margin-bottom:20px}.dock-title h3{margin:0;font-size:18px}.ghost-button{display:inline-flex;align-items:center;gap:7px;color:var(--secondary);padding:9px 12px;border:1px solid var(--line-strong);border-radius:10px}.control-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}.control{display:block;padding:16px;border:1px solid var(--line);border-radius:14px;background:var(--card)}.control>span{display:flex;justify-content:space-between;gap:12px;font-size:12px}.control output{color:var(--chapter-accent);font-variant-numeric:tabular-nums}.control input{width:100%;margin:18px 0 6px;accent-color:var(--chapter-accent)}.control small{display:flex;justify-content:space-between;color:var(--muted);font-size:9px}.chapter-close{margin-top:72px;display:flex;align-items:end;justify-content:space-between;gap:40px;padding:50px 0 40px;border-top:1px solid var(--line)}.chapter-close h2{max-width:720px;margin:0 0 10px;font-size:clamp(30px,4vw,52px);letter-spacing:-.04em}.chapter-close p{max-width:700px;color:var(--secondary);line-height:1.7}.source-line{display:flex;align-items:center;gap:8px;color:var(--muted);font-size:11px}.quiz-backdrop{position:fixed;top:0;right:0;bottom:0;left:0;z-index:80;display:flex;justify-content:flex-end;background:#01040ab8;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px)}.quiz-sheet{width:min(520px,100%);height:100%;overflow-y:auto;padding:38px;border-left:1px solid var(--line-strong);background:#0b1120;box-shadow:-30px 0 90px #00000080;animation:sheet .35s cubic-bezier(.2,.8,.2,1)}@keyframes sheet{0%{transform:translate(100%)}}.quiz-sheet header{display:flex;justify-content:space-between;gap:20px}.quiz-sheet h2{margin:0;font-size:30px;letter-spacing:-.04em}.quiz-prompt{margin:54px 0 25px;color:var(--text);font-size:18px;line-height:1.65}.quiz-options{display:grid;gap:10px;margin-bottom:22px}.quiz-options button{min-height:60px;display:grid;grid-template-columns:34px 1fr;align-items:center;gap:12px;padding:12px;border:1px solid var(--line);border-radius:13px;background:var(--surface);color:var(--secondary);text-align:left;cursor:pointer}.quiz-options button span{width:32px;height:32px;display:grid;place-items:center;border-radius:9px;background:var(--raised);color:var(--muted);font-size:11px}.quiz-options button.selected{border-color:var(--cyan);color:var(--text)}.quiz-options button.selected span{color:#04101b;background:var(--cyan)}.quiz-result{margin-top:20px;padding:20px;border:1px solid var(--line);border-radius:14px;background:var(--surface)}.quiz-result.correct{border-color:#34d39980}.quiz-result.incorrect{border-color:#fb718580}.result-label{display:flex;align-items:center;gap:10px;color:var(--green)}.quiz-result.incorrect .result-label{color:var(--danger)}.result-label svg{width:20px}.quiz-result p{color:var(--secondary);line-height:1.7}.text-button{display:flex;align-items:center;gap:5px;padding:0;color:var(--cyan)}@media(max-width:1120px){.topbar{grid-template-columns:auto 1fr auto}.topbar nav{display:none}.searchbox{justify-self:end;width:min(390px,100%)}.studyvis-link{display:none}.lesson-bench{grid-template-columns:230px minmax(0,1fr)}.index-panel{grid-column:1 / -1;border-left:0;border-top:1px solid var(--line)}.index-panel nav{grid-template-columns:repeat(5,1fr)}.index-panel>p,.objective{min-height:auto}}@media(max-width:780px){.topbar{height:60px;padding:0 16px;grid-template-columns:1fr auto}.brand{font-size:17px}.brand svg{width:28px}.searchbox{width:42px;padding:0 12px}.searchbox input{display:none}.library-page,.chapter-page{width:min(100% - 24px,720px)}.library-intro{min-height:490px;display:block;padding-top:90px}.library-intro h1{font-size:54px}.library-intro p{font-size:15px}.orbit-diagram{display:none}.chapter-grid{grid-template-columns:1fr}.chapter-card{min-height:330px}.chapter-card-icon{margin-top:32px}.chapter-head{grid-template-columns:1fr auto;padding:12px 0}.breadcrumb,.chapter-progress{display:none}.quiz-trigger{min-width:92px}.lens-tabs{width:100%;margin:12px 0}.lesson-bench{display:flex;flex-direction:column}.narrative-panel{order:2;border:0;border-top:1px solid var(--line)}.stage-panel{order:1}.index-panel{order:3}.model-svg{min-height:330px}.narrative-panel h1{font-size:40px}.narrative-steps li:not(.active):not(.done){display:none}.index-panel nav{grid-template-columns:1fr 1fr}.equation-row{align-items:start;flex-direction:column;justify-content:center;gap:5px}.control-grid{grid-template-columns:1fr}.dock-title{gap:18px}.chapter-close{margin-top:42px;align-items:start;flex-direction:column}.site-footer{flex-direction:column;gap:8px}.quiz-sheet{padding:24px}.quiz-prompt{margin-top:38px}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}