@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&family=Manrope:wght@400;500;600;700;800&display=swap');
:root{font-family:'DM Sans',sans-serif;color:#172832;background:#f4f7f9;--blue:#1676a3;--orange:#c35227;--line:#cdd8de}*{box-sizing:border-box}body{margin:0}button,input,a{-webkit-tap-highlight-color:transparent}button,input{font:inherit}button,a{touch-action:manipulation}button{cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #1676a3;outline-offset:4px}a{color:inherit;text-underline-offset:4px}header{height:84px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 4.5%;gap:24px}header a{font-size:14px;text-decoration:none}.brand{font-weight:800;letter-spacing:2px;display:flex;align-items:center;gap:12px}.brand:first-letter{font-size:28px}.edition{font-size:12px;letter-spacing:2px;color:#536776}main{max-width:1600px;margin:auto;padding:0 4.5%}.intro{display:flex;align-items:flex-end;justify-content:space-between;gap:35px;padding:42px 0 30px}.eyebrow{font-size:12px;font-weight:700;letter-spacing:1.7px;margin:0 0 14px;color:#526975}h1,h2,h3{font-family:Manrope,sans-serif}h1{font-size:clamp(38px,4.4vw,64px);line-height:1.07;letter-spacing:-2.8px;margin:0;font-weight:600}.intro>p{max-width:420px;color:#536975;font-size:17px;line-height:1.6;margin:0 0 5px}.lab{display:grid;grid-template-columns:minmax(0,1.7fr) minmax(320px,1fr);border:1px solid var(--line);border-radius:18px;overflow:hidden;background:#fff;box-shadow:0 16px 45px #25455808}.scene-wrap{position:relative;background:#e8eff3;min-width:0;min-height:610px;display:flex;flex-direction:column}.scene-top,.scene-bottom{display:flex;justify-content:space-between;align-items:center;padding:20px;gap:10px;z-index:2}.segmented{padding:4px;background:#d7e2e9;display:flex;border-radius:10px;gap:4px}button{border:1px solid #c8d6de;color:#243e4d;background:#fff;padding:10px 12px;border-radius:7px;font-size:14px}.segmented button{background:transparent;border:0;min-width:96px}.segmented button[aria-pressed=true]{background:#fff;color:var(--orange);box-shadow:0 2px 5px #17334415}.model-tag{font-size:10px;letter-spacing:1.5px;color:#617684}.scene-bottom{margin-top:auto;flex-wrap:wrap}.scene-bottom p{font-size:12px;color:#5b6f7d;margin:0}.view-tools{display:flex;gap:6px}.view-tools button{font-size:12px;padding:9px}button[aria-pressed=true]:not(.segmented button){background:#183e52;color:#fff;border-color:#183e52}#scene{position:absolute;inset:68px 0 64px;touch-action:none}#scene canvas{display:block;width:100%;height:100%;outline:none}#fallback{padding:50px;position:relative;z-index:1}.explanation{padding:28px 28px 23px;min-width:0;border-left:1px solid var(--line)}h2{font-weight:600;font-size:32px;letter-spacing:-1px;line-height:1.18;margin:0 0 16px}.explanation>p:not(.eyebrow):not(.caption){font-size:16px;line-height:1.6;color:#516772;min-height:102px}.balance{display:grid;grid-template-columns:1fr 12px 1fr 12px 1fr;align-items:center;padding:20px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);gap:5px}.balance span{display:block;font-size:12px;color:#587080;min-height:32px}.balance strong{font-size:24px;white-space:nowrap;font-weight:500}.balance small{font-size:13px}.balance .result strong{color:var(--orange)}.caption{font-size:12px;line-height:1.6;color:#5b6e7a}.component-buttons{display:grid;grid-template-columns:1fr 1fr;gap:7px;margin:20px 0 17px}.component-buttons button{text-align:left;font-size:12px;padding:11px 8px}.part-info{border-left:3px solid var(--blue);padding-left:15px}.part-info h3{font-size:16px;margin:0 0 8px}.part-info p{font-size:14px;line-height:1.6;color:#516772;margin:0;min-height:88px}.principle{padding:70px 0;display:grid;grid-template-columns:1fr 2fr 2fr;gap:32px;border-bottom:1px solid var(--line);align-items:start}.principle>p:last-child{margin:0;font-size:17px;line-height:1.7;color:#4d6574}.principle h2{font-size:30px}.costs{padding:64px 0}.section-heading{display:flex;justify-content:space-between;gap:40px;margin-bottom:30px;align-items:flex-end}.section-heading h2{font-size:40px;margin:0}.section-heading>p{max-width:450px;color:#536975;line-height:1.6}.calculator{display:grid;grid-template-columns:1fr 1.25fr;background:white;border-radius:18px;overflow:hidden;border:1px solid var(--line)}.inputs{padding:32px}.inputs h3{margin:0 0 25px;font-size:22px}.inputs>label{display:block;font-size:15px;margin:22px 0 10px}.inputs output{float:right;font-weight:700}.inputs input[type=range]{width:100%;accent-color:var(--blue);height:22px}.input-note{font-size:12px;line-height:1.6;color:#637781}.input-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:25px}.input-grid label,#compare-eff-wrap{font-size:14px}input[type=number]{display:block;width:100%;background:#f5f8fa;border:1px solid #c8d6de;border-radius:7px;padding:12px;margin-top:8px;color:#172832;font-size:17px}.text-button{border:0;background:none;padding-left:0;color:#14658c}.results{background:#123b4d;padding:36px;color:#fff}.results .eyebrow{color:#a9c6d5}.big-result{margin:30px 0 42px}.big-result strong{display:block;font-family:Manrope,sans-serif;font-size:clamp(42px,5vw,70px);font-weight:500;letter-spacing:-3px}.big-result>span{color:#c0d4df;font-size:17px}.bar-row{margin:23px 0}.bar-row>div:first-child{display:flex;justify-content:space-between;gap:16px;font-size:15px;margin-bottom:11px}.track{height:12px;background:#ffffff14;border-radius:3px;overflow:hidden}.track>div{height:100%;background:#7ee0d0;transition:width .25s;width:25%}.alternative .track>div{background:#96b3c2;width:100%}.bar-row small{display:block;color:#b4cbd6;margin-top:8px;font-size:12px}.metrics{display:grid;grid-template-columns:1fr 1fr 1fr;gap:15px;border-top:1px solid #446372;margin-top:30px;padding-top:25px}.metrics strong{display:block;font-size:27px;font-weight:500}.metrics span{display:block;font-size:12px;line-height:1.5;color:#b4cbd6;margin-top:8px}.results .caption{color:#aac4d1}.formula{font-size:14px;line-height:1.6;color:#cce0e9;padding:16px 0 3px}.benefits{border-top:1px solid var(--line);padding:50px 0 65px}.benefit-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:0 34px}.benefit-grid article{padding:28px 0 12px;border-top:1px solid var(--line)}.benefit-grid article>span{font-size:12px;color:#17708e}.benefit-grid h3{font-size:20px;line-height:1.4;font-weight:600}.benefit-grid p{font-size:15px;line-height:1.7;color:#536975}footer{border-top:1px solid var(--line);padding:32px 0 40px;display:grid;grid-template-columns:1fr 1fr;gap:18px 50px}footer p{font-size:13px;line-height:1.7;color:#5b707d}footer ol{margin:0;padding-left:20px;font-size:13px;line-height:2.2}footer>.caption{grid-column:1/-1;margin:0}[hidden]{display:none!important}@media(max-width:1100px){.lab{grid-template-columns:1.25fr 1fr}.scene-wrap{min-height:650px}.model-tag{display:none}.explanation{padding:24px 20px}.balance strong{font-size:20px}.principle{grid-template-columns:1fr 1fr}.principle>.eyebrow{grid-column:1/-1;margin-bottom:0}.metrics strong{font-size:22px}}@media(max-width:760px){header{height:68px}.edition{display:none}main{padding:0 5%}.intro{padding-top:28px;display:block}.intro>p{margin-top:22px;font-size:15px}h1{font-size:45px}.lab{display:flex;flex-direction:column}.scene-wrap{height:440px;min-height:440px}.scene-top{padding:14px}.scene-bottom{padding:14px}.scene-bottom p{width:100%}#scene{inset:65px 0 85px}.explanation{border-left:0;border-top:1px solid var(--line)}.explanation>p:not(.eyebrow):not(.caption){min-height:0}.part-info p{min-height:0}.balance strong{font-size:25px}.principle{display:block;padding:40px 0}.principle h2{margin-top:18px}.calculator{grid-template-columns:1fr}.inputs,.results{padding:25px}.section-heading{display:block}.section-heading h2{font-size:33px}.costs{padding:42px 0}.section-heading>p{font-size:15px}.benefit-grid{grid-template-columns:1fr 1fr;gap:20px}.benefit-grid h3{font-size:18px}.benefit-grid p{font-size:14px}footer{grid-template-columns:1fr}.metrics strong{font-size:24px}}@media(max-width:400px){header{gap:10px}.brand{font-size:12px;letter-spacing:1px}.benefit-grid{grid-template-columns:1fr}.metrics{gap:9px}.metrics strong{font-size:21px}.input-grid{gap:12px}.component-buttons{grid-template-columns:1fr 1fr}}@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition:none!important}}

/* 3D stage: studio backdrop, labels with leader lines, air legend, clearer season switch */
.scene-wrap{background:#e6e5e2}
#scene{z-index:1}
.scene-top,.scene-bottom{position:relative;z-index:3}
.segmented{padding:5px;gap:5px;background:#d9dcdd;border-radius:12px}
.segmented button{min-width:118px;padding:11px 16px;font-size:15px;font-weight:600;border-radius:9px;color:#38505d}
.segmented button#heating[aria-pressed=true]{background:#c35227;color:#fff;box-shadow:0 3px 10px rgba(195,82,39,.35)}
.segmented button#cooling[aria-pressed=true]{background:#1676a3;color:#fff;box-shadow:0 3px 10px rgba(22,118,163,.35)}
.scene-labels{position:absolute;inset:0;pointer-events:none;overflow:hidden}
.scene-labels svg{position:absolute;inset:0;width:100%;height:100%}
.scene-labels path{fill:none;stroke:#1f3a45;stroke-width:1.2;opacity:.7}
.scene-labels circle{fill:#fff;stroke:#1f3a45;stroke-width:1.6}
.scene-label{position:absolute;left:0;top:0;display:block;text-align:left;font:600 12.5px/1.25 'DM Sans',sans-serif;color:#16303a;background:rgba(255,255,255,.95);border:1px solid #c8d4d9;border-radius:7px;padding:6px 9px;max-width:205px;white-space:normal;pointer-events:none;box-shadow:0 2px 10px rgba(20,40,50,.1)}
.scene-label b{display:block;font-weight:700}
.scene-label small{display:block;font-weight:500;font-size:11.5px;color:#4f6774;margin-top:2px}
button.scene-label{pointer-events:auto;cursor:pointer}
button.scene-label:hover{border-color:#183e52}
.scene-label.active{border-color:#183e52;box-shadow:0 0 0 2px #183e52 inset,0 2px 10px rgba(20,40,50,.12)}
.scene-label.region{background:none;border:0;box-shadow:none;padding:0;font-size:11px;letter-spacing:2px;color:#4f6774}
.scene-label.region b{font-weight:700}
.air-legend{position:absolute;left:20px;bottom:70px;z-index:3;display:flex;gap:14px;flex-wrap:wrap;padding:7px 12px;border-radius:8px;background:rgba(255,255,255,.93);border:1px solid #d0dbdf;font:500 12px/1.3 'DM Sans',sans-serif;color:#1d3843;box-shadow:0 2px 10px rgba(20,40,50,.08);pointer-events:none}
.air-legend span{display:inline-flex;align-items:center;gap:6px}
.air-legend i{display:inline-block;width:18px;height:5px;border-radius:3px}
.air-legend .warm{background:#e8622f}.air-legend .cool{background:#2e8fd6}.air-legend .room{background:#9ba3a8}
.language-switch{margin-left:16px}
@media(max-width:760px){.scene-wrap{height:540px;min-height:540px}.segmented button{min-width:0;flex:1;padding:10px 12px;font-size:14px}.segmented{flex:1}.air-legend{left:8px;right:8px;top:66px;bottom:auto;justify-content:center;gap:9px;padding:4px 8px;font-size:10.5px;border-radius:6px}.air-legend i{width:12px}.scene-label{font-size:11px;padding:4px 7px;max-width:150px}.scene-label small{font-size:10.5px}.scene-label:not(.active) small{display:none}.model-tag{display:none}}

/* Dark theme: follow the site's ink and paper tokens */
html[data-theme=dark]{--line:#3a3631;--blue:#58aee0;--orange:#ee8656}
html[data-theme=dark] :root,html[data-theme=dark] body{color:#ece7df}
html[data-theme=dark] .scene-wrap,html[data-theme=dark] .rotary-surface{background:#1d1b18}
html[data-theme=dark] .lab,html[data-theme=dark] .calculator,html[data-theme=dark] .cycle-grid,html[data-theme=dark] .rotary-grid,html[data-theme=dark] .reverse-grid,html[data-theme=dark] .temperature-controls{background:#191714;border-color:var(--line);box-shadow:none}
html[data-theme=dark] .cycle-right{background:#1c1a17}
html[data-theme=dark] button{background:#22201c;color:#ece7df;border-color:#3d3933}
html[data-theme=dark] button[aria-pressed=true]:not(.segmented button),html[data-theme=dark] .language-switch button[aria-pressed=true]{background:#58aee0;color:#10181b;border-color:#58aee0}
html[data-theme=dark] .segmented{background:#2a2723}
html[data-theme=dark] .segmented button{background:transparent;color:#cfc7bc}
html[data-theme=dark] .segmented button#heating[aria-pressed=true]{background:#d4602f;color:#fff}
html[data-theme=dark] .segmented button#cooling[aria-pressed=true]{background:#2384b8;color:#fff}
html[data-theme=dark] .eyebrow,html[data-theme=dark] .model-tag,html[data-theme=dark] .scene-bottom p,html[data-theme=dark] .edition,html[data-theme=dark] .intro>p,html[data-theme=dark] .explanation>p:not(.eyebrow):not(.caption),html[data-theme=dark] .balance span,html[data-theme=dark] .caption,html[data-theme=dark] .part-info p,html[data-theme=dark] .principle>p:last-child,html[data-theme=dark] .section-heading>p,html[data-theme=dark] .input-note,html[data-theme=dark] .benefit-grid p,html[data-theme=dark] footer p,html[data-theme=dark] .process-detail p:not(.eyebrow),html[data-theme=dark] .temperature-lab p,html[data-theme=dark] .physics-notes p,html[data-theme=dark] .rotary-copy>p,html[data-theme=dark] .reverse-copy p,html[data-theme=dark] .coil-role-list span,html[data-theme=dark] .model-details,html[data-theme=dark] .mini-heading>span,html[data-theme=dark] .cycle-metrics span,html[data-theme=dark] .rotary-play-row>span,html[data-theme=dark] .defrost-controls>span,html[data-theme=dark] .state-table thead th,html[data-theme=dark] .state-table th>span{color:#b9b0a4}
html[data-theme=dark] .results .caption{color:#aac4d1}
html[data-theme=dark] .process-detail p.process-equation,html[data-theme=dark] .model-details summary,html[data-theme=dark] .mechanism-tabs button[aria-selected=true]{color:#ece7df;border-bottom-color:#ece7df}
html[data-theme=dark] .mechanism-tabs button{background:transparent;color:#b9b0a4}
html[data-theme=dark] .state-table .active-state{background:#24323a}
html[data-theme=dark] .engineering svg text{fill:#e4ddd3}
html[data-theme=dark] .engineering svg text.node-sub{fill:#b9b0a4}
html[data-theme=dark] .engineering a,html[data-theme=dark] .text-button{color:#7cc2e6}
html[data-theme=dark] input[type=number]{background:#22201c;border-color:#3d3933;color:#ece7df}
html[data-theme=dark] .benefit-grid article>span{color:#7cc2e6}
html[data-theme=dark] .scene-label{background:rgba(30,28,25,.95);color:#ece7df;border-color:#47423b;box-shadow:0 2px 10px rgba(0,0,0,.35)}
html[data-theme=dark] .scene-label small{color:#b9b0a4}
html[data-theme=dark] .scene-label.active{border-color:#58aee0;box-shadow:0 0 0 2px #58aee0 inset}
html[data-theme=dark] .scene-label.region{background:none;color:#b9b0a4}
html[data-theme=dark] .scene-labels path{stroke:#d9d1c6}
html[data-theme=dark] .scene-labels circle{fill:#1d1b18;stroke:#d9d1c6}
html[data-theme=dark] .air-legend{background:rgba(30,28,25,.94);border-color:#47423b;color:#ece7df}