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.3s,box-shadow .3s;overflow:hidden}.card:hover{box-shadow:var(--shadow-md);transform:translateY(-5px)}.card-header{background-color:var(--bg-surface-2);border-bottom:1px solid var(--border-color);padding:15px 20px}.card-header h2{margin:0;font-size:1.3rem}.card-body{padding:20px}.formula-item{border-bottom:1px dashed var(--border-color);margin-bottom:20px;padding-bottom:15px}.formula-item:last-child{border-bottom:none;margin-bottom:0;padding-bottom:0}.formula-name{color:var(--text-secondary);margin-bottom:8px;font-weight:600;display:block}.math-block{color:var(--text-primary);background:var(--bg-surface-2);text-align:center;border-radius:8px;margin:5px 0;padding:10px;font-size:1.1rem;overflow-x:auto}.note{color:var(--text-secondary);margin-top:5px;font-size:.85rem;font-style:italic}.card.first{border-top-color:var(--col-first)}.card.first h2{color:var(--col-first)}.card.second{border-top-color:var(--col-second)}.card.second h2{color:var(--col-second)}.card.entropy{border-top-color:var(--col-entropy)}.card.entropy h2{color:var(--col-entropy)}.card.carnot{border-top-color:var(--col-carnot)}.card.carnot h2{color:var(--col-carnot)}.card.work{border-top-color:var(--col-work)}.card.work h2{color:var(--col-work)}.card.heat{border-top-color:var(--col-heat)}.card.heat h2{color:var(--col-heat)}@media (width<=600px){.page-banner h1{font-size:1.5rem}.math-block{font-size:1rem}}:root{--secondary-color:#e53e3e;--accent-color:#dd6b20;--lecture-accent:#c53030}[data-theme=dark]{--secondary-color:#fc8181;--lecture-accent:#feb2b2}body{font-family:Hind Siliguri,sans-serif}.nav-container{background-color:var(--bg-surface);box-shadow:var(--shadow-md);z-index:900;border-left:5px solid var(--secondary-color);border-radius:12px;width:220px;max-height:80vh;padding:20px;position:fixed;top:55%;right:20px;overflow-y:auto;transform:translateY(-50%)}.nav-title{color:var(--primary-color);border-bottom:2px solid var(--border-color);text-align:center;margin-bottom:15px;padding-bottom:8px;font-size:1.1em;font-weight:700;display:block}.nav-links{margin:0;padding:0;list-style:none}.nav-links li{margin-bottom:8px}.nav-links a{color:var(--text-secondary);border-left:3px solid #0000;border-radius:4px;padding:5px;font-size:.9em;text-decoration:none;transition:all .3s;display:block}.nav-links a:hover{background-color:var(--bg-surface-2);color:var(--secondary-color);border-left-color:var(--secondary-color);padding-left:10px;font-weight:700}.container:has(.nav-container){padding-right:260px}@media (width<=992px){.container:has(.nav-container){padding-right:20px}.nav-container{border-left:none;border-top:5px solid var(--secondary-color);z-index:1100;border-radius:15px 15px 0 0;width:100%;max-height:30vh;padding:10px;position:fixed;inset:auto 0 0;transform:none;box-shadow:0 -2px 10px #0000001a}.nav-title{display:none}.nav-links{flex-wrap:wrap;justify-content:center;gap:5px;display:flex}.nav-links li{margin:0}.nav-links a{background:var(--bg-surface-2);border-left:none;border-radius:15px;padding:5px 10px;font-size:.8em}}.lecture-section{background:var(--bg-surface);box-shadow:var(--shadow-sm);border-top:5px solid var(--secondary-color);border-radius:10px;margin-bottom:40px;padding:30px}.lecture-section h2{color:var(--primary-color);border-bottom:1px solid var(--border-color);margin-top:0;margin-bottom:20px;padding-bottom:10px;font-size:1.6em}.lecture-section h3{color:var(--lecture-accent);margin-top:25px;margin-bottom:10px;font-size:1.25em}.lecture-section p,.lecture-section li{color:var(--text-primary);text-align:justify;font-size:1.05em;line-height:1.8}.lecture-section ul,.lecture-section ol{margin:10px 0;padding-left:20px}.lecture-section li{margin-bottom:6px}.def-box{background:var(--bg-surface-2);border-left:5px solid var(--secondary-color);border-radius:0 8px 8px 0;margin:15px 0;padding:15px 20px}.def-box .def-title{color:var(--secondary-color);margin-bottom:5px;font-size:1.05em;font-weight:700;display:block}.def-box p{margin:0}.key-point{border:1px solid var(--secondary-color);background:linear-gradient(135deg,#e53e3e14 0%,#e53e3e05 100%);border-radius:10px;margin:15px 0;padding:15px 20px;position:relative}.key-point:before{content:"💡";background:var(--bg-surface);padding:0 8px;font-size:1.2em;position:absolute;top:-12px;left:15px}.key-point .kp-title{color:var(--accent-color);margin-bottom:5px;font-weight:700;display:block}.math-display{background:var(--bg-surface-2);text-align:center;border-radius:8px;margin:10px 0;padding:12px;font-size:1.1em;overflow-x:auto}.lecture-table{border-collapse:collapse;width:100%;margin:15px 0;font-size:.95em}.lecture-table th,.lecture-table td{border:1px solid var(--border-color);text-align:left;padding:10px 15px}.lecture-table th{background:var(--bg-surface-2);font-weight:700}.lecture-table td{color:var(--text-primary)}.page-banner{text-align:center;background:linear-gradient(135deg,#1e3a8a 0%,#3b82f6 100%);border-radius:16px;width:100%;margin-bottom:40px;padding:32px 24px;position:relative;overflow:hidden;box-shadow:0 10px 25px #1e3a8a40;color:#fff!important}.page-banner h1,.page-banner h2{letter-spacing:-.01em;margin:0;font-size:2.3rem;font-weight:700;line-height:1.3;color:#fff!important}.page-banner p{opacity:.95;margin:12px 0 0;font-size:1.15rem;line-height:1.5;color:#dbeafe!important}[data-theme=dark] .page-banner{background:linear-gradient(135deg,#1e293b 0%,#1e40af 100%);border:1px solid #ffffff14;box-shadow:0 12px 30px #00000073}[data-theme=dark] .page-banner h1,[data-theme=dark] .page-banner h2{color:#fff!important}[data-theme=dark] .page-banner p{color:#bfdbfe!important}[data-theme=dark]{--col-cat1:#60a5fa!important;--col-cat2:#34d399!important;--col-cat3:#a78bfa!important;--col-cat4:#fb923c!important;--col-cat5:#f87171!important}.questions-grid{grid-template-columns:repeat(auto-fit,minmax(320px,1fr))!important;gap:25px!important;width:100%!important;display:grid!important}.cq-card{width:100%;min-height:100%}.container:not(:has(.nav-container)){padding-right:1.5rem!important}