#dodecahedron-lesson{--ink:#293c32;--green:#355846;--muted:#6b7367;--paper:#faf8f0;--line:#d5d5c7;--brass:#977443;max-width:1280px;padding:0 40px 50px;margin:auto;color:var(--ink);background:#fff;font:16px/1.6 Arial,Helvetica,sans-serif;container-type:inline-size;container-name:dd-study}
#dodecahedron-lesson *,#dodecahedron-lesson *::before,#dodecahedron-lesson *::after{box-sizing:border-box}
#dodecahedron-lesson{box-sizing:border-box}
#dodecahedron-lesson .icon-library{position:absolute;width:0;height:0;overflow:hidden}
#dodecahedron-lesson [hidden]{display:none!important}
#dodecahedron-lesson h1,#dodecahedron-lesson h2,#dodecahedron-lesson h3,#dodecahedron-lesson p,#dodecahedron-lesson figure{margin:0}
#dodecahedron-lesson h1,#dodecahedron-lesson h2{font-family:Georgia,'Times New Roman',serif;font-weight:400;line-height:1.16}
#dodecahedron-lesson h1{font-size:clamp(38px,5.4vw,58px);letter-spacing:-1.8px}
#dodecahedron-lesson h2{font-size:32px;letter-spacing:-.5px}
#dodecahedron-lesson button,#dodecahedron-lesson input,#dodecahedron-lesson select{font:inherit;color:inherit;border-radius:0}
#dodecahedron-lesson button{cursor:pointer}
#dodecahedron-lesson button:disabled{cursor:default;opacity:.55}
#dodecahedron-lesson a{color:var(--green);text-underline-offset:4px}
#dodecahedron-lesson button:focus-visible,#dodecahedron-lesson input:focus-visible,#dodecahedron-lesson select:focus-visible,#dodecahedron-lesson a:focus-visible,#dodecahedron-lesson summary:focus-visible,#dodecahedron-lesson .viewport:focus-visible{outline:3px solid var(--brass);outline-offset:3px}
#dodecahedron-lesson section[id]{scroll-margin-top:22px}
#dodecahedron-lesson button svg{width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:1.5;flex:none}
#dodecahedron-lesson .section-label{display:block;font-size:11px;font-weight:600;letter-spacing:1.6px;line-height:1.5;text-transform:uppercase;color:var(--brass);margin-bottom:10px}
#dodecahedron-lesson .intro{display:flex;align-items:flex-end;justify-content:space-between;gap:30px;padding:35px 0 28px}
#dodecahedron-lesson .intro-copy{font-size:14px;line-height:1.8;color:var(--muted);padding-bottom:4px}
#dodecahedron-lesson .site-nav{border-top:1px solid var(--line);border-bottom:1px solid var(--line);margin-bottom:30px}
#dodecahedron-lesson .nav-heading,#dodecahedron-lesson .nav-toggle{display:none}
#dodecahedron-lesson .section-links{display:grid;grid-template-columns:repeat(6,minmax(0,1fr));gap:15px}
#dodecahedron-lesson .section-links a{display:flex;align-items:center;gap:8px;min-height:54px;border-bottom:3px solid transparent;margin-bottom:-1px;font-size:12px;text-decoration:none;line-height:1.4}
#dodecahedron-lesson .index-number{font:11px Georgia,serif;color:var(--brass)}
#dodecahedron-lesson .section-links a[aria-current]{border-bottom-color:var(--green);font-weight:700}
#dodecahedron-lesson .section-links a:hover{color:#17291e;background:var(--paper)}
#dodecahedron-lesson .explorer{display:grid;grid-template-columns:minmax(0,1fr) 260px;column-gap:36px;row-gap:22px}
#dodecahedron-lesson .model-column{grid-column:1;grid-row:1;min-width:0}
#dodecahedron-lesson .model-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;margin:0 0 18px;min-height:65px}
#dodecahedron-lesson .model-heading h2{font-size:27px}
#dodecahedron-lesson .model-heading .section-label{margin-bottom:6px}
#dodecahedron-lesson .fullscreen-toggle{display:flex;align-items:center;gap:7px;min-height:44px;min-width:44px;padding:10px 0 10px 10px;border:0;background:none;white-space:nowrap;font-size:11px}
#dodecahedron-lesson .fullscreen-toggle:hover{color:var(--brass)}
#dodecahedron-lesson .model-drawing{border:1px solid var(--line);background:var(--paper);min-width:0}
#dodecahedron-lesson .stage{position:relative;overflow:hidden;height:540px;min-width:0}
#dodecahedron-lesson .stage-top{position:absolute;top:16px;left:16px;right:16px;z-index:4;pointer-events:none}
#dodecahedron-lesson .view-switch{display:inline-flex;max-width:100%;border:1px solid #babfaf;background:#fff;pointer-events:auto}
#dodecahedron-lesson .view-switch button{border:0;border-right:1px solid var(--line);background:transparent;min-height:38px;padding:7px 12px;font-size:11px;line-height:1.4;white-space:nowrap}
#dodecahedron-lesson .view-switch button:last-child{border-right:0}
#dodecahedron-lesson .view-switch button[aria-pressed=true]{background:var(--green);color:#fff}
#dodecahedron-lesson .view-switch button:hover{background:#e4eadd;color:var(--ink)}
#dodecahedron-lesson .viewport{position:absolute;inset:0;overflow:hidden;touch-action:none}
#dodecahedron-lesson .viewport canvas{position:absolute;inset:0;display:block;width:100%;height:100%;touch-action:none}
#dodecahedron-lesson #dd-annotations{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;z-index:2}
#dodecahedron-lesson #dd-annotations circle{fill:#faf8f0f0;stroke:#899b82;stroke-width:.8}
#dodecahedron-lesson #dd-annotations text{fill:var(--green);text-anchor:middle;font:11px Arial,sans-serif}
#dodecahedron-lesson #dd-annotations .edge-annotation path{fill:none;stroke:#5e765b;stroke-width:1}
#dodecahedron-lesson #dd-annotations .edge-annotation rect{fill:#faf8f0f2;stroke:var(--line);stroke-width:1}
#dodecahedron-lesson #dd-annotations .edge-annotation text{font-size:12px}
#dodecahedron-lesson .stage-bottom{position:absolute;bottom:14px;left:17px;right:15px;display:flex;align-items:center;justify-content:space-between;gap:8px;z-index:4;pointer-events:none}
#dodecahedron-lesson .gesture-hint{font-size:10px;color:var(--muted)}
#dodecahedron-lesson .camera-buttons{display:flex;gap:4px;pointer-events:auto}
#dodecahedron-lesson .camera-buttons button{display:grid;place-items:center;width:34px;height:34px;border:1px solid var(--line);background:#fff}
#dodecahedron-lesson .camera-buttons button:hover{background:#e4eadd}
#dodecahedron-lesson .view-toolbar{display:flex;justify-content:space-between;gap:8px;padding:6px 13px;border-top:1px solid var(--line);background:#f1f2e9}
#dodecahedron-lesson .view-toolbar button{display:flex;align-items:center;gap:6px;min-height:36px;padding:4px;border:0;background:none;font-size:11px;color:var(--muted)}
#dodecahedron-lesson .view-toolbar button[aria-pressed=true]{color:var(--green);font-weight:700}
#dodecahedron-lesson .view-toolbar button[aria-pressed=true] svg{stroke-width:2}
#dodecahedron-lesson .fold-control{position:absolute;z-index:4;bottom:59px;left:50%;transform:translateX(-50%);display:flex;align-items:center;gap:8px;padding:6px 10px;background:#fffffff5;border:1px solid var(--line);font-size:11px;white-space:nowrap}
#dodecahedron-lesson input[type=range]{accent-color:var(--green);cursor:pointer}
#dodecahedron-lesson .fold-control input{width:135px;min-height:30px;margin:0}
#dodecahedron-lesson .figure-caption{font-size:11px;line-height:1.65;color:var(--muted);padding-top:11px}
#dodecahedron-lesson .face-study{grid-column:2;grid-row:1;align-self:start;margin-top:83px;border-top:3px solid var(--brass);padding-top:19px;min-width:0}
#dodecahedron-lesson .face-study h3{font:24px/1.2 Georgia,serif;margin-bottom:12px}
#dodecahedron-lesson .face-study>p:not(.section-label){font-size:12px;line-height:1.75;color:var(--muted)}
#dodecahedron-lesson .face-index{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:7px;margin:18px 0}
#dodecahedron-lesson .face-index button{position:relative;display:grid;place-items:center;min-width:44px;min-height:57px;padding:5px;border:1px solid transparent;background:none}
#dodecahedron-lesson .face-index button svg{width:100%;height:auto;max-width:50px;stroke:none}
#dodecahedron-lesson .face-index button span{position:absolute;inset:0;display:grid;place-items:center;font-size:13px;font-weight:700;color:#fff;padding-top:5px;text-shadow:0 1px 2px #294a3870}
#dodecahedron-lesson .face-index button:hover{background:#eef1e8}
#dodecahedron-lesson .face-index button[aria-pressed=true]{border-color:var(--green);outline:1px solid var(--green);background:#eef1e8}
#dodecahedron-lesson .face-index button[data-opposite]{border:1px dashed var(--green);background:#f5f6ef}
#dodecahedron-lesson .insight{border-top:1px solid var(--line);padding-top:15px}
#dodecahedron-lesson .insight h3{font:700 13px/1.5 Arial,sans-serif;margin-bottom:5px}
#dodecahedron-lesson .insight p{font-size:12px;line-height:1.75;color:var(--muted)}
#dodecahedron-lesson .text-button{padding:6px 0;min-height:36px;border:0;background:none;text-decoration:underline;text-underline-offset:4px;font-size:12px;color:var(--green)}
#dodecahedron-lesson .face-study .atlas-note{font-size:10px!important;margin-top:15px}
#dodecahedron-lesson .dimension-band{grid-column:1/-1;grid-row:2;display:grid;grid-template-columns:minmax(250px,1.25fr) repeat(2,minmax(0,1fr));gap:0 30px;padding:24px 26px 12px;border-top:2px solid var(--green);border-bottom:1px solid var(--line);background:#eef1e8}
#dodecahedron-lesson .size-control{grid-column:1;grid-row:1/3;padding-right:28px;border-right:1px solid #c9d0c0;min-width:0}
#dodecahedron-lesson .size-control h3{font:22px/1.2 Georgia,serif;margin-bottom:14px}
#dodecahedron-lesson .size-fields{display:grid;grid-template-columns:100px minmax(0,1fr);gap:12px}
#dodecahedron-lesson .size-fields label{display:block;font-size:11px;margin-bottom:5px}
#dodecahedron-lesson .size-fields input,#dodecahedron-lesson .size-fields select{width:100%;height:40px;border:1px solid #bbc3b3;background:#fff;padding:6px 8px;font-size:13px}
#dodecahedron-lesson .size-fields input[aria-invalid=true]{border-color:#9e4231;outline:1px solid #9e4231}
#dodecahedron-lesson .size-control input[type=range]{width:100%;min-height:35px;margin:5px 0 0}
#dodecahedron-lesson .control-note{font-size:10px;color:var(--muted);line-height:1.6}
#dodecahedron-lesson [data-error]{font-size:11px;color:#913d2c;margin-bottom:8px}
#dodecahedron-lesson .live-measurement{min-width:0;padding-top:2px}
#dodecahedron-lesson .result-label{display:block;font-size:13px;font-weight:700;margin-bottom:14px}
#dodecahedron-lesson .live-value{display:flex;flex-wrap:wrap;align-items:baseline;gap:3px 7px;font:42px/1.1 Georgia,serif;letter-spacing:-1.3px;color:var(--green);margin-bottom:10px;overflow-wrap:anywhere}
#dodecahedron-lesson .live-value output{max-width:100%}
#dodecahedron-lesson .live-value [data-result-unit]{font:12px Arial,sans-serif;letter-spacing:0}
#dodecahedron-lesson .live-value .long-result{font-size:25px;letter-spacing:-.7px}
#dodecahedron-lesson .result-explanation{font-size:11px;color:var(--muted);line-height:1.6;display:block}
#dodecahedron-lesson .all-results-link{grid-column:2/-1;margin-top:18px;border-top:1px solid #c9d0c0;padding:11px 0 0;text-align:right;font-size:11px;text-decoration:none;align-self:end}
#dodecahedron-lesson .all-results-link span{margin-left:8px;font-size:17px}
#dodecahedron-lesson .shape-definition{display:grid;grid-template-columns:minmax(220px,.75fr) 2fr;gap:35px;border-bottom:1px solid var(--line);padding:27px 0 30px}
#dodecahedron-lesson .shape-definition h2{font-size:22px;padding-top:2px}
#dodecahedron-lesson .shape-definition p{font-size:14px;color:var(--muted);line-height:1.85}
#dodecahedron-lesson .shape-definition strong{color:var(--ink);font-weight:600}
#dodecahedron-lesson .pentagon-section{padding:39px 0 40px}
#dodecahedron-lesson .section-heading{margin-bottom:25px}
#dodecahedron-lesson .pentagon-layout{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.12fr);gap:65px;align-items:center}
#dodecahedron-lesson .pentagon-layout figure{background:var(--paper);padding:22px 25px 20px;text-align:center}
#dodecahedron-lesson .pentagon-plate{display:block;width:100%;height:auto;max-height:390px;overflow:visible}
#dodecahedron-lesson .pentagon-plate text{font:15px Georgia,serif;fill:var(--green);text-anchor:middle}
#dodecahedron-lesson .pentagon-layout figcaption{font-size:11px;color:var(--muted);margin-top:22px}
#dodecahedron-lesson .pentagon-copy>h3{font:24px/1.25 Georgia,serif;margin-bottom:10px}
#dodecahedron-lesson .pentagon-copy>p{font-size:14px;color:var(--muted);line-height:1.8}
#dodecahedron-lesson .action-link{display:inline-flex;align-items:center;gap:12px;min-height:44px;padding:9px 0;border:0;background:none;font-size:12px;color:var(--green);text-decoration:underline;text-underline-offset:5px}
#dodecahedron-lesson .action-link span{font-size:18px;text-decoration:none}
#dodecahedron-lesson .counting-proof{margin-top:22px}
#dodecahedron-lesson .counting-proof h3{font-size:11px;line-height:1.5;letter-spacing:.5px;color:var(--muted);margin-bottom:11px}
#dodecahedron-lesson .counting-proof button{width:100%;display:flex;align-items:center;gap:16px;min-height:75px;padding:11px 4px;border:0;border-top:1px solid var(--line);background:none;text-align:left}
#dodecahedron-lesson .counting-proof button:last-child{border-bottom:1px solid var(--line)}
#dodecahedron-lesson .counting-proof button[aria-pressed=true]{background:#f6f7f0}
#dodecahedron-lesson .counting-proof button:hover{background:#eef1e8}
#dodecahedron-lesson .count-number{width:43px;flex:none;font:32px/1 Georgia,serif;color:var(--green)}
#dodecahedron-lesson .counting-proof b{display:block;font-size:13px;font-weight:600}
#dodecahedron-lesson .counting-proof small{display:block;font-size:11px;color:var(--muted);line-height:1.7}
#dodecahedron-lesson .counting-proof button svg{margin-left:auto}
#dodecahedron-lesson .net-lesson{display:grid;grid-template-columns:minmax(0,.7fr) minmax(0,1.6fr);align-items:center;gap:38px;background:#f7f5eb;border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:30px 34px}
#dodecahedron-lesson .net-copy h2{font-size:39px;margin-bottom:18px}
#dodecahedron-lesson .net-copy p{font-size:13px;color:var(--muted);line-height:1.85;margin-bottom:12px}
#dodecahedron-lesson .net-figure{min-width:0}
#dodecahedron-lesson .net-figure img{display:block;width:100%;height:auto}
#dodecahedron-lesson .net-figure figcaption{font-size:10px;color:var(--muted);line-height:1.65;margin-top:8px;text-align:center}
#dodecahedron-lesson .measurements{display:grid;grid-template-columns:minmax(0,.72fr) minmax(0,2fr);gap:40px;margin-top:44px}
#dodecahedron-lesson .measurements .section-heading>p{font-size:12px;color:var(--muted);line-height:1.85;margin-top:18px}
#dodecahedron-lesson .text-link{display:inline-block;font-size:11px;min-height:44px;padding:12px 0}
#dodecahedron-lesson .formula-ledger{border-top:2px solid var(--green);min-width:0}
#dodecahedron-lesson .measurement{display:grid;grid-template-columns:130px minmax(0,1fr) minmax(105px,.7fr);align-items:center;gap:15px;padding:20px 0;border-bottom:1px solid var(--line)}
#dodecahedron-lesson .measurement-name h3{font-size:13px;line-height:1.5}
#dodecahedron-lesson .measurement-name p{font-size:10px;line-height:1.65;color:var(--muted);margin-top:4px}
#dodecahedron-lesson .formula{font:14px/1.6 Georgia,serif}
#dodecahedron-lesson .substitution{font-size:10px;color:var(--muted);margin-top:6px;overflow-wrap:anywhere}
#dodecahedron-lesson .measurement-value{font:27px/1.25 Georgia,serif;text-align:right;color:var(--green);overflow-wrap:anywhere;min-width:0}
#dodecahedron-lesson .measurement-value output{display:block}
#dodecahedron-lesson .measurement-value [data-result-unit]{font:10px Arial,sans-serif}
#dodecahedron-lesson .measurement-value .long-result{font-size:19px}
#dodecahedron-lesson .rounding-note{font-size:10px;line-height:1.7;color:var(--muted);padding-top:12px}
#dodecahedron-lesson .reference-diagram{border-top:1px solid var(--line);margin-top:40px;padding-top:39px}
#dodecahedron-lesson .reference-diagram img{display:block;width:100%;height:auto;border:1px solid var(--line)}
#dodecahedron-lesson .reference-diagram figcaption{font-size:11px;line-height:1.7;color:var(--muted);padding-top:11px}
#dodecahedron-lesson .properties{display:grid;grid-template-columns:minmax(0,.72fr) minmax(0,2fr);gap:40px;margin-top:31px;border-top:1px solid var(--line);padding-top:35px}
#dodecahedron-lesson .geometry-facts{margin:0}
#dodecahedron-lesson .geometry-facts>div{display:grid;grid-template-columns:150px minmax(0,1fr);gap:22px;border-bottom:1px solid var(--line);padding:0 0 16px;margin-bottom:16px;font-size:13px}
#dodecahedron-lesson .geometry-facts dt{font-weight:600}
#dodecahedron-lesson .geometry-facts dd{margin:0;color:var(--muted);line-height:1.8}
#dodecahedron-lesson .faq{margin-top:24px}
#dodecahedron-lesson .faq details{padding:14px 0;border-bottom:1px solid var(--line)}
#dodecahedron-lesson .faq summary{cursor:pointer;font-size:13px;font-weight:600;line-height:1.65;color:var(--green)}
#dodecahedron-lesson .faq p{font-size:13px;line-height:1.8;color:var(--muted);margin-top:12px}
#dodecahedron-lesson .reference-source{font-size:11px;line-height:1.8;color:var(--muted);margin-top:24px}
#dodecahedron-lesson .static-preview{position:absolute;inset:65px 20px 55px;display:flex;flex-direction:column;align-items:center;justify-content:center}
#dodecahedron-lesson .static-preview img{display:block;width:100%;height:calc(100% - 30px);max-height:400px;object-fit:contain}
#dodecahedron-lesson .static-preview span{font-size:12px;line-height:1.6;text-align:center}
#dodecahedron-lesson .sr-only{position:absolute;width:1px;height:1px;padding:0;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
#dodecahedron-lesson .no-script-note{font-size:12px;color:var(--muted);border-top:1px solid var(--line);padding:20px 0}
#dodecahedron-lesson .model-dialog{position:fixed;inset:0;width:100vw;height:100dvh;max-width:none;max-height:none;margin:0;padding:20px;border:0;background:#fff;overflow:auto;color:var(--ink)}
#dodecahedron-lesson .model-dialog::backdrop{background:#fff}
#dodecahedron-lesson .model-dialog .explorer{grid-template-columns:minmax(0,1fr) 230px;gap:16px 24px;min-height:100%;background:#fff}
#dodecahedron-lesson .explorer:fullscreen{width:100vw;height:100dvh;padding:20px;overflow:auto;background:#fff}
#dodecahedron-lesson .model-dialog .model-column{display:flex;flex-direction:column;min-height:400px}
#dodecahedron-lesson .model-dialog .model-drawing{display:flex;flex-direction:column;flex:1}
#dodecahedron-lesson .model-dialog .stage{height:auto;min-height:350px;flex:1}
#dodecahedron-lesson .model-dialog .dimension-band{align-self:end}
@container dd-study (max-width:1000px){
  #dodecahedron-lesson .explorer{grid-template-columns:minmax(0,1fr) 225px;column-gap:25px}
  #dodecahedron-lesson .stage{height:500px}
  #dodecahedron-lesson .fullscreen-toggle span{display:none}
  #dodecahedron-lesson .section-links{gap:8px}
  #dodecahedron-lesson .section-links a{font-size:11px;gap:6px}
  #dodecahedron-lesson .pentagon-layout{gap:35px}
  #dodecahedron-lesson .dimension-band{grid-template-columns:minmax(230px,1.2fr) repeat(2,minmax(0,1fr));column-gap:20px;padding-left:20px;padding-right:20px}
  #dodecahedron-lesson .size-control{padding-right:20px}
  #dodecahedron-lesson .live-value{font-size:36px}
  #dodecahedron-lesson .measurements{display:block}
  #dodecahedron-lesson .measurement{grid-template-columns:150px minmax(0,1fr) minmax(120px,.6fr)}
  #dodecahedron-lesson .properties{grid-template-columns:minmax(0,.7fr) minmax(0,2fr);gap:30px}
  #dodecahedron-lesson .geometry-facts>div{grid-template-columns:120px minmax(0,1fr);gap:15px}
}
@container dd-study (max-width:760px){
  #dodecahedron-lesson .intro{display:block;padding-top:28px}
  #dodecahedron-lesson .intro-copy{margin-top:16px;font-size:13px}
  #dodecahedron-lesson .site-nav{padding:12px 0 0}
  #dodecahedron-lesson .nav-heading{display:flex;align-items:center;justify-content:space-between;min-height:32px;margin-bottom:9px}
  #dodecahedron-lesson .nav-heading strong{font-size:12px;letter-spacing:.3px}
  #dodecahedron-lesson .nav-toggle{display:flex;align-items:center;gap:7px;min-height:36px;padding:5px 0 5px 12px;border:0;background:none;font-size:11px;color:var(--muted)}
  #dodecahedron-lesson .nav-toggle[aria-expanded=true] svg{transform:rotate(180deg)}
  #dodecahedron-lesson .section-links{grid-template-columns:repeat(3,minmax(0,1fr));gap:0 15px}
  #dodecahedron-lesson .section-links a{min-height:48px;font-size:12px}
  #dodecahedron-lesson .explorer{grid-template-columns:minmax(0,1fr);gap:22px}
  #dodecahedron-lesson .model-column{grid-column:1;grid-row:1}
  #dodecahedron-lesson .model-heading h2{font-size:25px}
  #dodecahedron-lesson .dimension-band{grid-column:1;grid-row:2;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px 25px;padding:23px 23px 12px}
  #dodecahedron-lesson .size-control{grid-column:1/-1;grid-row:1;border-right:0;border-bottom:1px solid #c9d0c0;padding:0 0 17px}
  #dodecahedron-lesson .size-fields{grid-template-columns:minmax(100px,1fr) minmax(0,1fr)}
  #dodecahedron-lesson .live-measurement{grid-row:2}
  #dodecahedron-lesson .live-value{font-size:40px}
  #dodecahedron-lesson .all-results-link{grid-column:1/-1;grid-row:3;margin-top:0}
  #dodecahedron-lesson .face-study{grid-column:1;grid-row:3;margin-top:0;display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:0 25px;padding-top:18px}
  #dodecahedron-lesson .face-study>.section-label,#dodecahedron-lesson .face-study>h3,#dodecahedron-lesson .face-study>p:not(.atlas-note){grid-column:1}
  #dodecahedron-lesson .face-index{grid-column:2;grid-row:1/5;margin:0;align-content:start;grid-template-columns:repeat(4,minmax(0,1fr));gap:5px}
  #dodecahedron-lesson .face-index button{min-height:50px}
  #dodecahedron-lesson .insight{grid-column:1/-1;margin-top:18px}
  #dodecahedron-lesson .face-study .atlas-note{grid-column:1/-1;margin-top:8px}
  #dodecahedron-lesson .shape-definition{display:block;margin-top:4px}
  #dodecahedron-lesson .shape-definition h2{margin-bottom:11px}
  #dodecahedron-lesson .pentagon-layout{grid-template-columns:minmax(0,1fr);gap:28px}
  #dodecahedron-lesson .pentagon-layout figure{max-width:100%;padding-top:16px}
  #dodecahedron-lesson .pentagon-plate{max-height:330px}
  #dodecahedron-lesson .net-lesson{display:block;padding:28px}
  #dodecahedron-lesson .net-copy h2 br{display:none}
  #dodecahedron-lesson .net-copy h2{font-size:32px}
  #dodecahedron-lesson .net-figure{margin-top:16px}
  #dodecahedron-lesson .properties{display:block}
  #dodecahedron-lesson .geometry-facts>div{grid-template-columns:150px minmax(0,1fr)}
}
@container dd-study (max-width:520px){
  #dodecahedron-lesson .section-links{grid-template-columns:repeat(2,minmax(0,1fr));gap:0 15px}
  #dodecahedron-lesson .section-links a{font-size:11px}
  #dodecahedron-lesson h2{font-size:28px}
  #dodecahedron-lesson .model-heading h2{font-size:24px;max-width:280px}
  #dodecahedron-lesson .model-heading .section-label{font-size:10px}
  #dodecahedron-lesson .stage{height:420px}
  #dodecahedron-lesson .stage-top{top:12px;left:10px;right:10px}
  #dodecahedron-lesson .view-switch{display:flex;width:100%}
  #dodecahedron-lesson .view-switch button{flex:1;padding:8px 5px;font-size:10px}
  #dodecahedron-lesson .stage-bottom{left:11px;right:10px}
  #dodecahedron-lesson .gesture-hint{font-size:9px;max-width:145px}
  #dodecahedron-lesson .camera-buttons{gap:3px}
  #dodecahedron-lesson .camera-buttons button{width:32px;height:34px}
  #dodecahedron-lesson .view-toolbar{padding:5px 8px;gap:4px}
  #dodecahedron-lesson .view-toolbar button{font-size:10px;gap:4px}
  #dodecahedron-lesson .view-toolbar svg{width:14px;height:14px}
  #dodecahedron-lesson .fold-control{font-size:10px;gap:6px;padding:5px 8px;bottom:57px}
  #dodecahedron-lesson .fold-control input{width:105px}
  #dodecahedron-lesson .dimension-band{padding:22px 16px 12px;column-gap:16px}
  #dodecahedron-lesson .live-value{font-size:33px;letter-spacing:-1px}
  #dodecahedron-lesson .live-value .long-result{font-size:21px}
  #dodecahedron-lesson .result-label{margin-bottom:10px}
  #dodecahedron-lesson .result-explanation{font-size:10px}
  #dodecahedron-lesson .face-study{grid-template-columns:minmax(0,1fr) minmax(140px,1fr);column-gap:15px}
  #dodecahedron-lesson .face-study h3{font-size:21px}
  #dodecahedron-lesson .face-study>p:not(.section-label){font-size:11px}
  #dodecahedron-lesson .face-index{grid-template-columns:repeat(3,minmax(0,1fr));gap:3px}
  #dodecahedron-lesson .face-index button{min-height:46px;padding:4px;min-width:44px}
  #dodecahedron-lesson .pentagon-layout figure{padding-left:12px;padding-right:12px}
  #dodecahedron-lesson .net-lesson{padding:24px 17px}
  #dodecahedron-lesson .measurement{grid-template-columns:minmax(0,1fr) minmax(100px,.9fr);gap:8px 15px;padding:17px 0}
  #dodecahedron-lesson .measurement-name{grid-column:1;grid-row:1}
  #dodecahedron-lesson .measurement-value{grid-column:2;grid-row:1}
  #dodecahedron-lesson .measurement-calculation{grid-column:1/-1;grid-row:2}
  #dodecahedron-lesson .substitution{margin-top:3px}
  #dodecahedron-lesson .geometry-facts>div{grid-template-columns:minmax(0,1fr);gap:7px}
}
@media(max-width:600px){#dodecahedron-lesson{padding:0 19px 35px}}
@media(max-width:760px){
  #dodecahedron-lesson .model-dialog{padding:10px}
  #dodecahedron-lesson .model-dialog .explorer{grid-template-columns:minmax(0,1fr)}
  #dodecahedron-lesson .explorer:fullscreen{padding:10px}
  #dodecahedron-lesson .model-dialog .model-column{grid-column:1;grid-row:1;height:77dvh;min-height:490px}
  #dodecahedron-lesson .model-dialog .dimension-band{grid-column:1;grid-row:2}
  #dodecahedron-lesson .model-dialog .face-study{grid-column:1;grid-row:3;margin-top:0}
}
@media(prefers-reduced-motion:reduce){#dodecahedron-lesson *,#dodecahedron-lesson *::before,#dodecahedron-lesson *::after{scroll-behavior:auto!important}}

#dodecahedron-lesson .intro{display:block}
#dodecahedron-lesson .intro-copy{margin-top:16px;font-size:16px;max-width:none}

/* Shared reading and navigation behavior; each lesson keeps its composition. */
#dodecahedron-lesson .mobile-contents { display: none; }
#dodecahedron-lesson .mobile-contents summary { list-style: none; }
#dodecahedron-lesson .mobile-contents summary::-webkit-details-marker { display: none; }

@media (max-width: 760px) {
  #dodecahedron-lesson [data-desktop-contents] { display: none !important; }
  #dodecahedron-lesson .mobile-contents { display: block; }
}
@container dd-study (max-width: 760px) {
  #dodecahedron-lesson [data-desktop-contents] { display: none !important; }
  #dodecahedron-lesson .mobile-contents { display: block; }
}
#dodecahedron-lesson .mobile-contents {
  margin: 20px 0 24px;
  padding: 0;
  max-width: none;
  border: 1px solid var(--line, #ccd6dc);
  border-radius: 3px;
  background: #fff;
  color: var(--ink, #294e69);
  font: 15px/1.45 Arial, Helvetica, sans-serif;
}
#dodecahedron-lesson .mobile-contents > summary {
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 56px;
  padding: 12px 16px;
  cursor: pointer;
  background: var(--tint, var(--paper, #f4f7f9));
  color: inherit;
}
#dodecahedron-lesson .mobile-contents .contents-title { font-weight: 700; }
#dodecahedron-lesson .mobile-contents .contents-count {
  margin-left: auto;
  font-size: 12px;
  font-weight: 400;
  color: var(--muted, #617582);
  white-space: nowrap;
}
#dodecahedron-lesson .mobile-contents > summary::after {
  content: '';
  width: 7px;
  height: 7px;
  flex: none;
  margin-left: 3px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: translateY(-2px) rotate(45deg);
}
#dodecahedron-lesson .mobile-contents[open] > summary { border-bottom: 1px solid var(--line, #ccd6dc); }
#dodecahedron-lesson .mobile-contents[open] > summary::after { transform: translateY(2px) rotate(225deg); }
#dodecahedron-lesson .mobile-contents nav { display: block; padding: 0 16px; margin: 0; border: 0; }
#dodecahedron-lesson .mobile-contents ol { list-style: none; padding: 0; margin: 0; }
#dodecahedron-lesson .mobile-contents li { padding: 0; margin: 0; border-bottom: 1px solid var(--line, #dce3e7); }
#dodecahedron-lesson .mobile-contents li:last-child { border-bottom: 0; }
#dodecahedron-lesson .mobile-contents a {
  display: grid;
  grid-template-columns: 22px minmax(0, 1fr) 18px;
  align-items: center;
  gap: 10px;
  min-height: 50px;
  padding: 11px 0;
  color: inherit;
  font-size: 14px;
  line-height: 1.45;
  text-decoration: none;
  overflow-wrap: break-word;
}
#dodecahedron-lesson .mobile-contents .contents-number { font-size: 11px; color: var(--muted, #617582); font-variant-numeric: tabular-nums; }
#dodecahedron-lesson .mobile-contents .contents-arrow { color: var(--accent, var(--green, #315f81)); }
#dodecahedron-lesson .mobile-contents a:hover { color: var(--accent, var(--green, #315f81)); text-decoration: underline; text-underline-offset: 3px; }
#dodecahedron-lesson .mobile-contents a:focus-visible, #dodecahedron-lesson .mobile-contents summary:focus-visible { outline: 2px solid var(--accent, var(--green, #315f81)); outline-offset: -3px; }

/* Keep the mode labels readable and separate them from the full-screen action. */
@media (max-width: 760px) {
  #dodecahedron-lesson .model-toolbar, #dodecahedron-lesson .viewer-bar { flex-wrap: wrap; gap: 10px; }
  #dodecahedron-lesson .mode-tabs, #dodecahedron-lesson .mode-buttons { flex: 1 0 100%; display: flex; flex-wrap: wrap; gap: 6px; }
  #dodecahedron-lesson .mode-tabs button, #dodecahedron-lesson .mode-buttons button { flex: 1 1 auto; min-height: 44px; padding: 9px 12px; font-size: 13px; white-space: normal; }
  #dodecahedron-lesson .model-toolbar .fullscreen, #dodecahedron-lesson .viewer-bar .fullscreen { margin-left: auto; min-height: 44px; padding: 9px 12px; font-size: 13px; }
  #dodecahedron-lesson .viewer-bar .fullscreen span { display: inline; }
  #dodecahedron-lesson .camera-controls button { min-width: 44px; min-height: 44px; font-size: 13px; }
  #dodecahedron-lesson .stage-top .view-switch { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); width: 100%; gap: 5px; border: 0; background: transparent; }
  #dodecahedron-lesson .stage-top .view-switch button { min-height: 44px; padding: 9px 8px; font-size: 13px; border: 1px solid var(--line, #ccd6dc); background: #fff; white-space: normal; }
  #dodecahedron-lesson .stage-top .view-switch button[aria-pressed=true] { background: var(--green, #315f81); color: #fff; }
  #dodecahedron-lesson .stage > .viewport { top: 112px; }
  #dodecahedron-lesson .stage { min-height: 480px; }
  #dodecahedron-lesson .camera-buttons button, #dodecahedron-lesson .camera-bar button { min-width: 44px; min-height: 44px; }
}
@container dd-study (max-width: 760px) {
  #dodecahedron-lesson .model-toolbar, #dodecahedron-lesson .viewer-bar { flex-wrap: wrap; gap: 10px; }
  #dodecahedron-lesson .mode-tabs, #dodecahedron-lesson .mode-buttons { flex: 1 0 100%; display: flex; flex-wrap: wrap; gap: 6px; }
  #dodecahedron-lesson .mode-tabs button, #dodecahedron-lesson .mode-buttons button { flex: 1 1 auto; min-height: 44px; padding: 9px 12px; font-size: 13px; white-space: normal; }
  #dodecahedron-lesson .model-toolbar .fullscreen, #dodecahedron-lesson .viewer-bar .fullscreen { margin-left: auto; min-height: 44px; padding: 9px 12px; font-size: 13px; }
  #dodecahedron-lesson .viewer-bar .fullscreen span { display: inline; }
  #dodecahedron-lesson .camera-controls button { min-width: 44px; min-height: 44px; font-size: 13px; }
  #dodecahedron-lesson .stage-top .view-switch { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); width: 100%; gap: 5px; border: 0; background: transparent; }
  #dodecahedron-lesson .stage-top .view-switch button { min-height: 44px; padding: 9px 8px; font-size: 13px; border: 1px solid var(--line, #ccd6dc); background: #fff; white-space: normal; }
  #dodecahedron-lesson .stage-top .view-switch button[aria-pressed=true] { background: var(--green, #315f81); color: #fff; }
  #dodecahedron-lesson .stage > .viewport { top: 112px; }
  #dodecahedron-lesson .stage { min-height: 480px; }
  #dodecahedron-lesson .camera-buttons button, #dodecahedron-lesson .camera-bar button { min-width: 44px; min-height: 44px; }
}
#dodecahedron-lesson .featured-pin {
  --pin-ink: #223b48;
  --pin-muted: #536672;
  --pin-rule: #cbd3d4;
  margin-top: 56px;
  color: var(--pin-ink);
  container-type: inline-size;
  container-name: pin-reference;
}
#dodecahedron-lesson .featured-pin * { box-sizing: border-box; }
#dodecahedron-lesson .featured-pin h2 { margin: 0; font: 42px/1.12 Georgia, serif; letter-spacing: -1.1px; color: inherit; }
#dodecahedron-lesson .featured-pin h3 { margin: 0; color: inherit; }
#dodecahedron-lesson .featured-pin p { margin: 0; max-width: none; }
#dodecahedron-lesson .featured-pin .pin-intro { margin: 18px 0 26px; font-size: 15px; line-height: 1.75; color: var(--pin-muted); }
#dodecahedron-lesson .featured-pin .pin-art { width: 100%; max-width: 420px; margin: 0; justify-self: center; min-width: 0; }
#dodecahedron-lesson .featured-pin .pin-preview { display: block; line-height: 0; background: #fff; box-shadow: 0 8px 24px #132e3914; }
#dodecahedron-lesson .featured-pin .pin-preview img { display: block; width: 100%; max-width: 100%; height: auto; aspect-ratio: 2 / 3; border: 1px solid #17344326; }
#dodecahedron-lesson .featured-pin .pin-preview:hover { outline: 2px solid var(--pin-ink); outline-offset: 4px; }
#dodecahedron-lesson .featured-pin figcaption { margin: 14px 0 0; padding: 0; text-align: center; font: 12px/1.5 Arial, sans-serif; color: var(--pin-muted); }
#dodecahedron-lesson .featured-pin .pin-actions { display: flex; flex-wrap: wrap; align-items: stretch; gap: 10px; margin-top: 26px; }
#dodecahedron-lesson .featured-pin .pin-actions :is(a, button) { display: inline-flex; justify-content: center; align-items: center; gap: 10px; min-height: 46px; padding: 10px 18px; font: 600 14px/1.4 Arial, sans-serif; text-decoration: none; border: 1px solid var(--pin-ink); border-radius: 0; cursor: pointer; }
#dodecahedron-lesson .featured-pin .pin-actions .pin-pinterest { flex: 0 0 auto; padding-inline: 14px; background: #bd081b; border-color: #bd081b; color: #fff; }
#dodecahedron-lesson .featured-pin .pin-actions .pin-pinterest:hover { background: #9b0716; border-color: #9b0716; }
#dodecahedron-lesson .featured-pin .pin-save { background: transparent; color: var(--pin-ink); }
#dodecahedron-lesson .featured-pin .pin-enlarge { background: transparent; color: var(--pin-ink); }
#dodecahedron-lesson .featured-pin .pin-actions a:hover { text-decoration: underline; text-underline-offset: 4px; }
#dodecahedron-lesson .featured-pin :is(a, button):focus-visible { outline: 3px solid var(--pin-ink); outline-offset: 4px; }
#dodecahedron-lesson .featured-pin .pin-actions svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.6; }
#dodecahedron-lesson .featured-pin .pin-return { display: inline-flex; align-items: center; gap: 10px; min-height: 44px; margin-top: 16px; font-size: 13px; color: var(--pin-ink); text-underline-offset: 4px; }
#dodecahedron-lesson .featured-pin .pin-sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
@container pin-reference (max-width: 700px) {
  #dodecahedron-lesson .featured-pin h2 { font-size: 34px; letter-spacing: -.7px; }
  #dodecahedron-lesson .featured-pin .pin-art { max-width: 420px; }
  #dodecahedron-lesson .featured-pin .pin-intro { font-size: 15px; margin: 15px 0 22px; }
}
@media (max-width: 600px) {
  #dodecahedron-lesson .featured-pin { margin-top: 36px; }
}

#dodecahedron-lesson .featured-pin { --pin-ink: #2c4e3e; --pin-muted: #607064; --pin-rule: #d1d7c9; }
#dodecahedron-lesson .pentagon-reference { display: grid; grid-template-columns: minmax(0, 1.03fr) minmax(0, 1fr); grid-template-rows: auto 1fr; gap: 0 58px; padding: 38px 28px; border-top: 1px solid #87977f; border-bottom: 1px solid var(--pin-rule); }
#dodecahedron-lesson .pentagon-reference-heading { grid-column: 2; grid-row: 1; padding-top: 12px; }
#dodecahedron-lesson .pentagon-reference .pin-art { grid-column: 1; grid-row: 1 / 3; }
#dodecahedron-lesson .pentagon-reference-notes { grid-column: 2; grid-row: 2; }
#dodecahedron-lesson .pentagon-reference-counts { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); margin: 0 0 25px; padding: 18px 0; border-top: 1px solid var(--pin-rule); border-bottom: 1px solid var(--pin-rule); }
#dodecahedron-lesson .pentagon-reference-counts > div { padding-left: 20px; border-left: 1px solid var(--pin-rule); }
#dodecahedron-lesson .pentagon-reference-counts > div:first-child { padding-left: 0; border-left: 0; }
#dodecahedron-lesson .pentagon-reference-counts dt { font: 40px/1.1 Georgia, serif; }
#dodecahedron-lesson .pentagon-reference-counts dd { margin: 5px 0 0; font-size: 12px; color: var(--pin-muted); }
#dodecahedron-lesson .pentagon-reference-entry { margin-top: 20px; }
#dodecahedron-lesson .pentagon-reference-entry h3 { font: 21px/1.3 Georgia, serif; }
#dodecahedron-lesson .pentagon-reference-entry p { margin-top: 8px; font-size: 14px; line-height: 1.7; color: var(--pin-muted); }
@container pin-reference (max-width: 900px) { #dodecahedron-lesson .pentagon-reference { padding: 30px 0; column-gap: 32px; } #dodecahedron-lesson .pentagon-reference h2 { font-size: 36px; } }
@container pin-reference (max-width: 700px) {
  #dodecahedron-lesson .pentagon-reference { grid-template-columns: minmax(0, 1fr); gap: 0; padding: 28px 0; }
  #dodecahedron-lesson .pentagon-reference-heading { grid-column: 1; grid-row: 1; padding-top: 0; }
  #dodecahedron-lesson .pentagon-reference .pin-art { grid-column: 1; grid-row: 2; margin: 0 0 28px; }
  #dodecahedron-lesson .pentagon-reference-notes { grid-column: 1; grid-row: 3; }
}