:root{--topbar-h: 44px}body{margin:0;padding-top:var(--topbar-h);font-family:Inter,sans-serif;font-weight:700;font-feature-settings:"liga" 1,"calt" 1;background:#0f1320;color:#e6edf3}.container{max-width:960px;margin:6vh auto;padding:24px}.actions{margin-top:12px;display:flex;gap:12px}a{color:#4f8cff;text-decoration:none}a:hover{text-decoration:underline}.card,.card:hover,.card:focus,.card:focus-visible,.card .card-body h3,.card:hover .card-body h3{text-decoration:none}.btn{display:inline-flex;align-items:center;justify-content:center;height:32px;padding:0 12px;border-radius:8px;border:0;background:#833e33;color:#fff;font-weight:600;font-size:.9rem;line-height:1;cursor:pointer;text-decoration:none}.btn.secondary{background:#2b2f36}.btn:hover{text-decoration:none}.grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px}@media (max-width: 1100px){.grid{grid-template-columns:repeat(3,minmax(0,1fr))}}@media (max-width: 800px){.grid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media (max-width: 520px){.grid{grid-template-columns:1fr}}.grid{gap:40px}.card{position:relative;display:block;border-radius:30px;overflow:hidden;background:#f3e0c2;border:2px solid #354268a1;box-shadow:0 2px 6px #2018101f,0 1px 2px #2018101a;transition:transform .18s ease,box-shadow .18s ease,border-color .18s ease;text-decoration:none;color:inherit}.card:hover{transform:translateY(-2px);box-shadow:0 12px 28px #20181038,0 6px 12px #20181024;border-color:#203b4f2e}.card:focus-visible{outline:3px solid #203B4F;outline-offset:2px}.card .thumb{width:100%;padding-top:100%;background-size:cover;background-position:center;transition:none}.card-gradient{position:absolute;left:0;right:0;bottom:0;height:56%;background:linear-gradient(to top,#00000080,#0000);pointer-events:none}.card-title{position:absolute;left:14px;right:14px;bottom:12px;margin:0;color:#833e33;font-weight:100;font-size:.5rem;line-height:1.2;text-shadow:0 1px 2px rgba(172,9,9,.35);word-break:break-word;border:10px solid #833e33}.card-body{padding:20px}.card-body h3{margin:0;font-family:Georgia,Times New Roman,Times,serif;font-weight:800;font-size:1.2rem;color:#833e33;text-align:center}.topbar{position:fixed;top:0;left:0;right:0;z-index:1000;display:flex;align-items:center;gap:10px;padding:6px 12px;min-height:var(--topbar-h);background:#0f1320;border-bottom:1px solid rgba(255,255,255,.08)}.topbar .brand{font-weight:700;color:#e6edf3;text-decoration:none;font-size:.95rem}.topbar .spacer{flex:1}.topbar .btn{margin-left:8px}.topbar .contact{color:#e6edf3;margin-right:8px;white-space:nowrap;font-size:.9rem;opacity:.95}@media (max-width: 420px){.topbar .contact{display:none}}.topic-nav{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:24px}.home-hero{--home-offset: -90px;min-height:calc(100vh - var(--topbar-h));display:grid;place-items:center;padding:24px}.home-hero--light{background:#d3bc95;color:#111827;position:relative;overflow:hidden}.home-hero--light:before{content:"";position:absolute;inset:0;background-image:url(/bg-physics-tile.svg);background-repeat:repeat;background-size:300px 300px;pointer-events:none}.home-card{text-align:center;max-width:520px;transform:translateY(var(--home-offset));transition:transform .2s ease;position:relative;z-index:1}.hero-logo{width:clamp(180px,24vw,270px);height:auto;margin:0 auto 12px;display:block}.wordmark{margin:0;font-weight:800;letter-spacing:.08em;line-height:1.1;text-transform:uppercase;font-size:clamp(28px,4.8vw,44px)}.subtitle{margin:10px 0 22px;font-size:clamp(15px,2.6vw,20px);opacity:.9}.home-panel{background:#f4ebd6;border:2px solid rgba(41,65,83,.801);box-shadow:#00000048;border-radius:0;padding:28px 28px 24px;width:clamp(320px,48vw,120px);margin:0 auto;position:relative;z-index:1}.home-panel .hero-logo{margin-bottom:10px}.home-panel .subtitle{margin:8px 0 18px}.page--light{background:#d3bc95;color:#111827;position:relative;overflow:hidden;min-height:calc(100vh - var(--topbar-h));padding-bottom:40vh}.page--light:before{content:"";position:absolute;inset:0;background-image:url(/bg-physics-tile.svg);background-repeat:repeat;background-size:300px 300px;pointer-events:none}.page-content{position:relative;z-index:1}.page--light.page--topic-bg{background:#e8dcc4}.gsi-material-button{-moz-user-select:none;-webkit-user-select:none;-ms-user-select:none;-webkit-appearance:none;user-select:none;appearance:none;background-color:#f2f2f2;background-image:none;border:none;border-radius:9999px;box-sizing:border-box;color:#1f1f1f;cursor:pointer;font-family:Roboto,arial,sans-serif;font-size:14px;height:38px;letter-spacing:.25px;outline:none;overflow:hidden;padding:0 12px;position:relative;text-align:center;transition:background-color .218s,border-color .218s,box-shadow .218s;vertical-align:middle;white-space:nowrap;width:auto;max-width:400px;min-width:min-content}.gsi-material-button .gsi-material-button-icon{height:20px;width:20px;min-width:20px;margin-right:12px}.gsi-material-button .gsi-material-button-content-wrapper{display:flex;align-items:center;flex-direction:row;flex-wrap:nowrap;justify-content:space-between;height:100%;width:100%;position:relative}.gsi-material-button .gsi-material-button-contents{flex-grow:1;font-family:Roboto,arial,sans-serif;font-weight:500;overflow:hidden;text-overflow:ellipsis;vertical-align:top}.gsi-material-button .gsi-material-button-state{transition:opacity .218s;position:absolute;inset:0;opacity:0}.gsi-material-button:disabled{cursor:default;background-color:#ffffff61}.gsi-material-button:disabled .gsi-material-button-state{background-color:#1f1f1f1f}.gsi-material-button:disabled .gsi-material-button-contents,.gsi-material-button:disabled .gsi-material-button-icon{opacity:38%}.gsi-material-button:not(:disabled):active .gsi-material-button-state,.gsi-material-button:not(:disabled):focus .gsi-material-button-state{background-color:#001d35;opacity:12%}.gsi-material-button:not(:disabled):hover{box-shadow:0 1px 2px #3c40434d,0 1px 3px 1px #3c404326}.gsi-material-button:not(:disabled):hover .gsi-material-button-state{background-color:#001d35;opacity:8%}.gsi-frame{--frame-gap: 2px;--frame-offset-x: 0px;--frame-offset-y: 0px;display:inline-flex;align-items:center;justify-content:center;padding:var(--frame-gap);background:#203b4f;border-radius:9999px;line-height:0;overflow:hidden;box-sizing:border-box}.gsi-frame__inner{transform:translate(var(--frame-offset-x),var(--frame-offset-y))}.dashboard-header{display:flex;justify-content:center;align-items:center;margin:8px 0 10px}.page-title{margin:6px 0 16px}.page--light .page-content{padding-top:8px}.dash-subtitle{margin:8px 0 10px;font-size:clamp(15px,2.2vw,18px);opacity:.9;color:#111827;text-align:center}.page-title--center{text-align:center;margin:6px 0 18px}.dashboard-header{display:flex;flex-direction:column;justify-content:center;align-items:center;margin:8px 0 10px}.dash-logo{width:clamp(160px,18vw,240px);height:auto;display:block}.dash-title{margin:8px 0 18px;text-align:center;color:#253555;font-size:clamp(30px,2.8vw,24px);font-weight:500;font-family:Times New Roman,Times,serif;font-feature-settings:"liga" 1,"calt" 1}body.topic-topbar-scroll{padding-top:0}body.topic-topbar-scroll .topbar{position:static}@media (max-width: 960px){.topic-layout{grid-template-columns:1fr}}:root{--topic-page-width: 340px;--topic-offset-x: -300px;--topic-offset-y: 0px;--topic-page-min-h: 64vh;--topic-page-padding: 28px 24px}.topic-frame{margin-left:var(--topic-offset-x);margin-top:var(--topic-offset-y)}.topic-align{width:var(--topic-page-width)}.topic-crumb{margin:0 0 8px;padding-bottom:6px;border-bottom:1px solid rgba(32,59,79,.28);color:#253555}.topic-crumb a{color:inherit;text-decoration:none}.topic-crumb a:hover{text-decoration:underline}.topic-heading{margin:10px 0 12px;color:#253555;line-height:1.2}.topic-layout{display:grid;grid-template-columns:var(--topic-page-width) 1fr;gap:24px;align-items:start}.topic-page{background:#f3e0c2;border:2px solid rgba(32,59,79,.28);border-radius:8px;padding:var(--topic-page-padding);min-height:var(--topic-page-min-h)}.topic-title{margin:0 0 8px;color:#253555}.topic-content{color:#111827;line-height:1.6;white-space:normal}.topic-aside{min-height:120px}@media (max-width: 960px){.topic-frame{margin-left:0;margin-top:0}.topic-align{width:100%}.topic-layout{grid-template-columns:1fr}}.topic-controls{display:inline-flex;gap:8px;margin:6px 0 12px}.topic-header{display:flex;align-items:center;justify-content:space-between;gap:12px;margin:10px 0 12px}.topic-actions{display:inline-flex;gap:8px}.ql-container.ql-snow{min-height:260px;border-radius:8px}.ql-toolbar.ql-snow{border-radius:8px}.video-embed{position:relative;width:100%;padding-top:56.25%;border-radius:8px;overflow:hidden;background:#000}.video-embed iframe{position:absolute;inset:0;width:100%;height:100%;border:0}.topic-content .katex{font-size:1.05em}.re-container{border:1px solid rgba(0,0,0,.15);border-radius:8px;background:#203b4f0d}.re-toolbar{display:flex;gap:8px;align-items:center;padding:6px;border-bottom:1px solid rgba(0,0,0,.12)}.re-toolbar .re-group select{padding:4px 6px}.re-editor{min-height:240px;padding:10px;background:#fff;color:#1f1f1f;border-radius:0 0 8px 8px}.re-editor:focus{outline:2px solid rgba(32,59,79,.25)}.re-editor .katex{font-size:1.05em}.topic-layout{display:grid;grid-template-columns:var(--topic-page-width) minmax(240px,1fr);gap:24px;align-items:start}.resizable-img{display:inline-block;resize:both;overflow:auto;padding:4px;max-width:100%}.resizable-img img{max-width:100%;height:auto;display:block}.resizable-img.left{float:left;margin:0 12px 12px 0}.resizable-img.right{float:right;margin:0 0 12px 12px}.resizable-img.center{display:block;margin:0 auto 12px;float:none}:root{--math-shift: -.2em}.ql-formula{display:inline-block}.ql-formula,.ql-formula>.katex{vertical-align:var(--math-shift)!important}.topic-content .katex,.topic-page .katex,.re-editor-page .katex{font-size:1em;line-height:1}.ql-formula,.ql-formula>.katex{display:inline-block;vertical-align:var(--math-shift, -.2em)!important}:root{--math-shift: 0em}.topic-page .katex,.topic-content .katex,.re-editor-page .katex{font-size:1.1em;line-height:1}.ql-formula,.ql-formula>.katex{display:inline-block;vertical-align:var(--math-shift)!important}.topic-content{white-space:normal}.re-editor-page{font-size:16px;line-height:1.6}.re-editor-page .fs-s,.topic-content .fs-s{font-size:12px!important}.re-editor-page .fs-m,.topic-content .fs-m{font-size:27px!important}.re-editor-page .fs-l,.topic-content .fs-l{font-size:30px!important}.page--light.page--topic-bg{background:#d3bc95}.page--light.page--topic-bg:before{content:none}.page--light.page--topic-bg .topic-page{border-color:#203b4f7a}.playlist{--pl-text: #2C1E14;--pl-panel: #F3E0C2;--pl-rail: rgba(48, 34, 25, .55);--pl-dot: #3A2A1F;--pl-pill: #833e33;--pl-pillText: #FFF7F2;--pl-shadow: rgba(0,0,0,.12);padding:0;color:var(--pl-text)}.playlist-title{font-weight:800;font-size:1rem;margin-bottom:10px;color:var(--pl-text)}.pl-panel{background:var(--pl-panel);border:1px solid rgba(80,60,40,.12);border-radius:16px;padding:12px 14px 14px;box-shadow:0 4px 12px var(--pl-shadow);overflow:hidden}.pl-module-head{display:block;font-weight:800;color:var(--pl-text);text-decoration:none;padding:6px 6px 8px;border-radius:8px}.pl-module-head:hover{background:#2c1e140f}.pl-track{position:relative;--tl-center: 20px;--gap: 18px;--dot: 10px;--cap: 20px}.pl-rail{position:absolute;left:var(--tl-center);top:6px;bottom:6px;width:2px;background:var(--pl-rail)}.pl-timeline{margin:4px 0 2px;padding-left:calc(var(--tl-center) + var(--gap));list-style:none!important}.pl-timeline>li{margin:10px 0;list-style:none!important;position:relative}.pl-dot{position:relative;display:block;width:0;height:0}.pl-dot:before{content:"";position:absolute;left:calc(-1 * var(--gap) - var(--dot)/2);top:1.05em;transform:translateY(-50%);width:var(--dot);height:var(--dot);border-radius:50%;background:var(--pl-dot);box-shadow:0 0 0 2px var(--pl-panel) inset}.pl-item{position:relative;display:block;text-decoration:none;color:var(--pl-text);padding:6px 10px;border-radius:10px;line-height:1.38}.pl-item:hover{background:#2c1e140d}.pl-timeline>li.is-active .pl-dot{display:none}.pl-timeline>li.is-active .pl-item:before{content:"";position:absolute;left:calc(-1 * var(--cap));top:0;bottom:0;width:var(--cap);background:var(--pl-pill);border-top-left-radius:14px;border-bottom-left-radius:14px}.pl-explore{margin-top:14px}.pl-explore-title{font-weight:800;font-size:1rem;margin:10px 0 6px;color:var(--pl-text)}.pl-explore-list{list-style:disc;padding-left:20px;margin:0}.pl-explore-link{color:var(--pl-text);text-decoration:none}.pl-explore-link:hover{text-decoration:underline}.playlist .pl-timeline,.playlist .pl-timeline>li{list-style-type:none!important}.playlist .pl-timeline>li::marker{content:""!important}.pl-item{position:relative;display:block;text-decoration:none;color:var(--pl-text);padding:6px 10px;border-radius:10px;line-height:1.38;font-weight:600}.pl-timeline>li.is-active .pl-item{background:var(--pl-pill);color:var(--pl-pillText);font-weight:800;border-radius:0 14px 14px 0;padding:10px 14px;box-shadow:0 3px 8px var(--pl-shadow);z-index:1}.pl-panel{--panel-pad: 14px}.pl-timeline>li.is-active .pl-item{margin-left:calc(-1 * (var(--tl-center, 20px) + var(--gap, 18px) - var(--panel-pad, 14px)));margin-right:calc(-1 * var(--panel-pad, 14px))}.pl-timeline>li.is-active .pl-item:before{--cap: calc(var(--tl-center, 20px) - var(--panel-pad, 14px) + 2px);left:calc(-1 * var(--cap));width:var(--cap)}.pl-explore-list--thumbs{list-style:none;padding-left:0;display:grid;gap:10px}.pl-explore-item{text-align:center}.pl-explore-link{display:block;text-decoration:none;color:var(--pl-text, #2C1E14)}.pl-explore-thumb{width:100%;height:auto;display:block}.pl-explore-name{margin-top:6px;font-weight:600;line-height:1.3}.pl-explore{--thumb-w: 110px}.pl-explore-list--thumbs{list-style:none;padding-left:0;display:grid;gap:8px;justify-items:center}.pl-explore-thumb{width:var(--thumb-w);max-width:100%;height:auto;display:block;margin:0 auto}.pl-explore-name{margin-top:6px;font-weight:600;line-height:1.3;font-size:.95rem}