.ih{--ih-ink:#163849;--ih-muted:#496575;--ih-paper:#fff;--ih-soft:#f1f6f6;--ih-line:#d5e3e4;--ih-accent:#086769;max-width:1380px;margin:0 auto;padding:26px 28px 48px;color:var(--ih-ink);font-family:Inter,sans-serif;line-height:1.6}.ih *,.ih ::after,.ih ::before{box-sizing:border-box}.ih [hidden]{display:none!important}.ih h1,.ih h2,.ih h3,.ih p{margin:0;color:inherit;font-family:inherit}.ih button,.ih input,.ih select{font:inherit}.ih button,.ih select{min-height:44px}.ih button{cursor:pointer}.ih button:disabled{opacity:.5;cursor:default}.ih :is(button,select,input,summary,a,[tabindex]):focus-visible{outline:3px solid 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var(--ih-line)}.ih-stage-detail h2{font-size:1.7rem;letter-spacing:-.035em;margin:5px 0 14px}.ih-stage-detail>p:not(.ih-eyebrow){font-size:1.04rem;line-height:1.85}.ih-discuss{border-left:3px solid #cb842c;background:var(--ih-soft);border-radius:0 8px 8px 0;padding:18px 22px;margin-top:26px}.ih-discuss>span{color:var(--ih-muted);font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;font-weight:700}.ih-discuss h3{font-size:1.04rem;margin:7px 0 12px}.ih summary{cursor:pointer;color:var(--ih-accent);font-weight:650;min-height:44px;padding:9px 0}.ih details p{margin-top:10px}.ih-section-intro{display:flex;gap:20px;justify-content:space-between;align-items:center;margin-bottom:20px}.ih-section-intro h2{font-size:1.5rem;letter-spacing:-.025em;margin:4px 0}.ih-section-intro p:not(.ih-eyebrow){color:var(--ih-muted);font-size:.88rem}.ih-section-intro>button{flex:none}.ih-answer-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.ih-answer-card{padding:20px;background:var(--ih-paper);border:1px solid var(--ih-line);border-radius:12px}.ih-answer-card label{display:flex;align-items:center;gap:8px;font-size:.85rem;font-weight:650;margin-bottom:12px}.ih-answer-card select{width:100%;font-size:.88rem}.ih-feedback{margin-top:13px!important;font-size:.87rem}.ih-feedback[data-state]{padding:12px;border-radius:6px}.ih-feedback[data-state=correct]{color:#125642;background:#e8f6ee;border-left:3px solid #238164}.ih-feedback[data-state=retry]{color:#74430a;background:#fff3dc;border-left:3px solid #b27215}.ih [aria-invalid=true]{border-color:#a86410}.ih-subheading{font-size:1.05rem;margin:24px 0 14px!important}.ih-check-row{display:flex;align-items:center;gap:20px;margin-top:20px}.ih-check-row p{font-size:.88rem}.ih-question{padding:24px;border:1px solid var(--ih-line);background:var(--ih-paper);border-radius:12px;margin-bottom:16px}.ih-question fieldset{padding:0;margin:0 0 14px;border:0;min-width:0}.ih-question legend{display:block;width:100%;margin-bottom:18px}.ih-question legend>span{display:block}.ih-question-title{font-size:1.13rem;font-weight:700;margin-top:8px}.ih-option{display:flex;align-items:flex-start;gap:12px;border:1px solid var(--ih-line);border-radius:8px;padding:12px 14px;margin-top:8px;cursor:pointer;font-size:.92rem}.ih-option:has(input:checked){border-color:var(--ih-accent);background:var(--ih-soft)}.ih-option input{margin-top:4px;width:18px;height:18px;accent-color:#086769;flex:none}.ih-teacher-note{border-top:1px solid var(--ih-line);margin-top:30px;padding-top:14px;font-size:.85rem;color:var(--ih-muted)}.ih-teacher-note a{color:var(--ih-accent);text-decoration:underline}.ih-tool-status{margin-top:10px!important;font-size:.85rem}.ih-note{padding:14px;background:var(--ih-paper)}.ih-print-only{display:none}.ih:fullscreen{max-width:none;width:100%;height:100%;overflow:auto;background:var(--ih-soft);padding:18px 30px}.ih:fullscreen .ih-heading{margin-bottom:12px}.ih:fullscreen .ih-back,.ih:fullscreen .ih-heading .ih-eyebrow,.ih:fullscreen .ih-lead{display:none}.ih:fullscreen .ih-heading h1{font-size:1.7rem;margin:0}.ih:fullscreen .ih-scene-scroll{max-width:1200px;margin:auto}[data-theme=dark] .ih{--ih-ink:#e0ecee;--ih-muted:#b2c5cd;--ih-paper:#172e38;--ih-soft:#10242d;--ih-line:#3b555e;--ih-accent:#7edbd0}@media screen and (max-width:1000px){.ih-heading{align-items:flex-start;flex-direction:column;gap:16px}.ih-heading-actions{justify-content:flex-start}.ih-discovery-grid{grid-template-columns:280px 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5mm}.ih-print-page-two{break-before:page}.ih-print-question{break-inside:avoid;margin-bottom:7mm}.ih-print-credit{font-size:8pt;margin-top:8mm!important}.ih[data-print-kind=answer] .ih-print-student{display:none!important}.ih:not([data-print-kind=answer]) .ih-print-answer{display:none!important}.ih:not([data-print-kind=answer]) .ih-print-only [data-history-label]{visibility:hidden}.ih[data-print-kind=answer] .ih-print-only [data-history-label]{visibility:visible}.ih .ih-print-only [hidden]{display:initial!important}}.ih .ih-landscape{min-width:0;padding:24px;background:#eef3f8;color:#213b53}.ih-timeline-title{display:flex;flex-direction:column;gap:5px;margin-bottom:20px}.ih-timeline-title span{font-size:.7rem;font-weight:750;letter-spacing:.12em}.ih-timeline-title strong{font-size:1.4rem}.ih .ih-track{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:16px;margin:0;padding:0;list-style:none}.ih-time-card{background:#fff;border:1px solid #cbd8e3;border-top:5px solid #294f74;border-radius:12px;padding:14px;min-width:0}.ih-card-top{display:flex;gap:8px;align-items:center;font-size:.67rem;min-height:38px}.ih .ih-card-date{font-size:1.8rem;line-height:1.2;margin:16px 0;letter-spacing:-.03em}.ih .ih-card-date{font-size:1.5rem}.ih-card-slot{font-size:.93rem;font-weight:650;line-height:1.45;min-height:70px}.ih-timeline-footer{font-size:.76rem;margin-top:20px!important}.ih[data-mode=build] .ih-scene-card [data-history-label]{display:none}.ih[data-mode=build] .ih-scene-card [data-history-placement]{display:flex;align-items:center;padding:8px;border:2px dashed #086769;border-radius:8px;background:#eff8f5}.ih-comparator{padding:22px;margin:20px 0;border:1px solid var(--ih-line);border-radius:14px;background:var(--ih-paper)}.ih-comparator h2{font-size:1.4rem;margin:6px 0 14px}.ih-comparator p{font-size:.87rem}.ih-compare-controls{display:grid;grid-template-columns:1fr 1fr;gap:12px}.ih-compare-controls label{display:flex;flex-direction:column;gap:6px;font-size:.83rem;font-weight:650;min-width:0}#ih-duration{margin:16px 0;font-size:1.05rem;font-weight:750}.ih-time-ruler{display:block;width:100%;margin:10px 0}.ih .ih-scene-scroll::after{display:none}@media screen and (max-width:900px){.ih .ih-track{grid-template-columns:1fr 1fr}}@media screen and (max-width:480px){.ih .ih-track,.ih-compare-controls{grid-template-columns:1fr}.ih .ih-landscape{padding:14px}.ih-card-slot{min-height:44px}}@media print{.ih .ih-print-only .ih-landscape{padding:3mm}.ih .ih-print-only .ih-track{grid-template-columns:repeat(4,minmax(0,1fr));gap:2mm}.ih-print-only .ih-time-card{padding:2mm;border-top-width:1mm;break-inside:avoid}.ih-print-only .ih-card-top{font-size:6.5pt;min-height:8mm;gap:1mm}.ih-print-only .ih-number{width:5mm;height:5mm;font-size:7pt}.ih .ih-print-only .ih-card-date{font-size:17pt;margin:2mm 0}.ih .ih-print-only .ih-card-date{font-size:13pt}.ih-print-only .ih-card-slot{font-size:8pt;min-height:16mm}.ih-print-only .ih-timeline-title{display:none}.ih-print-only .ih-timeline-footer{font-size:7pt}}.ih-innovation{padding:24px;border:1px solid var(--ih-line);border-radius:14px;background:var(--ih-paper)}.ih-innovation h2{font-size:1.45rem;margin:8px 0 18px}.ih-innovation>label{display:block;font-size:.85rem;font-weight:650;margin-bottom:6px}.ih-chain{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:22px;margin:24px 0 16px}.ih-chain>div{position:relative;border:1px solid var(--ih-line);border-top:4px solid var(--ih-accent);border-radius:10px;background:var(--ih-soft);padding:18px}.ih-chain>div+div::before{content:'→';position:absolute;left:-20px;top:45%;color:var(--ih-accent);font-weight:800}.ih-chain span{display:block;color:var(--ih-accent);font-size:.7rem;font-weight:750;letter-spacing:.06em;margin-bottom:12px}.ih-chain p{font-size:.88rem}.ih-chain h3{font-size:1.08rem;margin-bottom:8px}.ih-chain-note{color:var(--ih-muted)!important;font-size:.8rem}@media screen and (max-width:900px){.ih-chain{grid-template-columns:1fr 1fr}.ih-chain>div:nth-child(3)::before{content:none}}@media screen and (max-width:480px){.ih-chain{grid-template-columns:1fr}.ih-chain>div+div::before{content:'↓';top:-26px;left:48%}.ih-innovation{padding:16px}}.ih-object{display:block;width:100%;height:auto;object-fit:contain;margin:6px auto 14px}.ih[data-mode=build] .ih-scene-card .ih-object{visibility:hidden}@media print{.ih-print-only .ih-object{display:none}}.ih-time-ruler{position:relative;height:110px;background:#f1f5fa;border-radius:12px;color:#365767}.ih-ruler-description{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap}.ih-ruler-axis{position:absolute;left:3%;width:94%;top:54px;height:3px;background:#7f91a7}.ih-ruler-tick{position:absolute;top:35px;height:30px;border-left:1.5px solid #7f91a7}.ih-ruler-tick>span{position:absolute;top:-27px;transform:translateX(-50%);font-size:clamp(10px, 1.4vw, 17px)}.ih-ruler-interval{position:absolute;top:51px;height:9px;background:#086769}.ih-ruler-point{position:absolute;top:47px;width:16px;height:16px;transform:translateX(-50%);border-radius:50%;background:#086769}.ih-ruler-boundary{position:absolute;left:3%;bottom:10px;font-size:clamp(11px, 1.4vw, 17px)}.ih-ruler-boundary-end{left:auto;right:3%}