:root{--paper:#14171f;--paper-deep:#1b1f29;--grid-line:#d2dcf00d;--grid-line-major:#d2dcf01a;--card:#1c212b;--card-edge:#d2dcf024;--ink:#e7ebf5;--ink-soft:#a8b1c7;--ink-faint:#6c7690;--surface-inv:#101521;--ink-on-bright:#16202e;--accent-1:#5fa0e0;--accent-1-bg:#5fa0e029;--accent-2:#e2776a;--accent-2-bg:#e2776a29;--accent-3:#b79ee0;--accent-3-bg:#b79ee029;--accent-4:#58c79b;--accent-4-bg:#58c79b29;--amber:#e3b94d;--highlight:#f5de7a;--highlight-soft:#4a421e;--mono:ui-monospace, "Cascadia Mono", "SF Mono", Menlo, Consolas, monospace;--sans:-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;--serif:Georgia, "Times New Roman", serif;--sidebar-w:288px;--content-max:840px;--sidebar-bg:var(--surface-inv);--sidebar-scheme:dark;--sidebar-ink:#dce3f0;--sidebar-brand:#8fa3d6;--sidebar-h1:#f4f6fb;--sidebar-sub:#98a4c2;--sidebar-divider:#37436a;--sidebar-link:#c4cce3;--sidebar-link-hover-bg:#232f52;--sidebar-link-hover-ink:#fff;--sidebar-link-active-bg:#2b3a66;--sidebar-link-active-ink:#fff;--sidebar-tag:#7286bc;--sidebar-tag-active:#9fb4ee;--sidebar-progress:#8592b4;--sidebar-scrollbar-thumb:#37436a;--sidebar-scrollbar-thumb-hover:#465388;--sidebar-chip-border:#37436a;--sidebar-toggle-border:#4a5686;--sidebar-toggle-ink:#b7c1e0}:root[data-theme=light]{--paper:#fff;--paper-deep:#f1f3f7;--grid-line:#141e3c0b;--grid-line-major:#141e3c17;--card:#fff;--card-edge:#141e3c29;--ink:#14171f;--ink-soft:#45506b;--ink-faint:#767f94;--accent-1:#1d5ea8;--accent-1-bg:#1d5ea81a;--accent-2:#b23a2c;--accent-2-bg:#b23a2c1a;--accent-3:#6a4fb0;--accent-3-bg:#6a4fb01a;--accent-4:#1f8a63;--accent-4-bg:#1f8a631a;--amber:#8a6710;--highlight:#fce896;--highlight-soft:#fff6d6;--sidebar-bg:#eef1f8;--sidebar-scheme:light;--sidebar-ink:#1b2233;--sidebar-brand:#5a6c94;--sidebar-h1:#1b2233;--sidebar-sub:#5f6a87;--sidebar-divider:#d3d8e6;--sidebar-link:#384158;--sidebar-link-hover-bg:#dce2f2;--sidebar-link-hover-ink:#1b2233;--sidebar-link-active-bg:#cbd5ef;--sidebar-link-active-ink:#16202e;--sidebar-tag:#6b7691;--sidebar-tag-active:#2b6cb0;--sidebar-progress:#6b7691;--sidebar-scrollbar-thumb:#c3cadc;--sidebar-scrollbar-thumb-hover:#a9b3cc;--sidebar-chip-border:#d3d8e6;--sidebar-toggle-border:#c3cadc;--sidebar-toggle-ink:#5f6a87}*{box-sizing:border-box}html{scroll-behavior:smooth}body{font-family:var(--sans);color:var(--ink);background:var(--paper);margin:0;font-size:16px;line-height:1.62}.page{background-image:linear-gradient(var(--grid-line) 1px, transparent 1px), linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);background-size:28px 28px;min-height:100vh}::selection{background:var(--highlight);color:var(--ink-on-bright)}a{color:var(--accent-1)}.shell{align-items:flex-start;display:flex}.sidebar{height:100vh;width:var(--sidebar-w);flex:0 0 var(--sidebar-w);background:var(--sidebar-bg);color:var(--sidebar-ink);border-right:6px solid var(--paper-deep);color-scheme:var(--sidebar-scheme);scrollbar-width:thin;scrollbar-color:var(--sidebar-scrollbar-thumb) var(--sidebar-bg);padding:26px 22px 22px;position:sticky;top:0;overflow-y:auto}.sidebar::-webkit-scrollbar{width:10px}.sidebar::-webkit-scrollbar-track{background:var(--sidebar-bg)}.sidebar::-webkit-scrollbar-thumb{background:var(--sidebar-scrollbar-thumb);border:2px solid var(--sidebar-bg);border-radius:6px}.sidebar::-webkit-scrollbar-thumb:hover{background:var(--sidebar-scrollbar-thumb-hover)}.sidebar .brand{font-family:var(--mono);letter-spacing:.12em;text-transform:uppercase;color:var(--sidebar-brand);margin-bottom:4px;font-size:12.5px}.sidebar h1{font-family:var(--serif);color:var(--sidebar-h1);margin:2px 0 4px;font-size:21px;font-weight:600;line-height:1.3}.navlist{margin:0;padding:0;list-style:none}.navlist li{margin-bottom:2px}.navlist a{color:var(--sidebar-link);border-radius:6px;align-items:baseline;gap:10px;padding:7px 9px;font-size:13.6px;text-decoration:none;transition:background .15s,color .15s;display:flex}.navlist a:hover{background:var(--sidebar-link-hover-bg);color:var(--sidebar-link-hover-ink)}.navlist a.active{background:var(--sidebar-link-active-bg);color:var(--sidebar-link-active-ink)}.navlist .tag{font-family:var(--mono);color:var(--sidebar-tag);min-width:30px;font-size:11px}.navlist a.active .tag{color:var(--sidebar-tag-active)}.sidebar .progress-note{border-top:1px dashed var(--sidebar-divider);color:var(--sidebar-progress);margin-top:22px;padding-top:16px;font-size:12px;line-height:1.55}.theme-toggle{border:1px solid var(--sidebar-toggle-border);border-radius:20px;gap:0;margin-top:16px;display:flex;overflow:hidden}.theme-toggle button{font-family:var(--mono);letter-spacing:.04em;cursor:pointer;color:var(--sidebar-toggle-ink);background:0 0;border:none;flex:1 1 0;padding:7px 0;font-size:11.5px}.theme-toggle button.active{background:var(--highlight);color:var(--ink-on-bright);font-weight:700}.sidebar-collapse-btn,.sidebar-expand-btn{z-index:900;border:1px solid var(--sidebar-chip-border);background:var(--sidebar-bg);width:26px;height:40px;color:var(--sidebar-toggle-ink);cursor:pointer;border-left:none;border-radius:0 8px 8px 0;justify-content:center;align-items:center;font-size:15px;display:flex;position:fixed;top:22px;box-shadow:0 6px 18px #0000004d}.sidebar-collapse-btn:hover,.sidebar-expand-btn:hover{color:var(--sidebar-link-hover-ink)}.sidebar-collapse-btn{left:var(--sidebar-w)}.sidebar-expand-btn{display:none;left:0}:root[data-sidebar=collapsed] .sidebar,:root[data-sidebar=collapsed] .sidebar-collapse-btn{display:none}:root[data-sidebar=collapsed] .sidebar-expand-btn{display:flex}:root[data-chat=off] .chat-fab{display:none}.search-trigger{border:1px solid var(--sidebar-chip-border);background:var(--sidebar-bg);width:100%;color:var(--sidebar-brand);font-family:var(--mono);cursor:pointer;border-radius:8px;justify-content:space-between;align-items:center;margin:16px 0 4px;padding:9px 12px;font-size:12px;transition:border-color .15s,color .15s;display:flex}.search-trigger:hover{border-color:var(--sidebar-toggle-border);color:var(--sidebar-link-hover-ink)}.search-trigger kbd{font-family:var(--mono);border:1px solid var(--sidebar-chip-border);color:var(--sidebar-toggle-ink);border-radius:4px;padding:2px 6px;font-size:10.5px}.search-overlay{z-index:1000;background:#080a108c;padding:12vh 20px 20px;display:none;position:fixed;inset:0}.search-overlay.open{display:block}.search-panel{background:var(--card);border:1px solid var(--card-edge);color-scheme:dark;scrollbar-width:thin;scrollbar-color:var(--ink-faint) transparent;border-radius:12px;flex-direction:column;max-width:560px;max-height:calc(88vh - 40px);margin:0 auto;display:flex;overflow:hidden auto;box-shadow:0 20px 60px #00000073}:root[data-theme=light] .search-panel{color-scheme:light}.search-panel::-webkit-scrollbar{width:8px}.search-panel::-webkit-scrollbar-track{background:0 0}.search-panel::-webkit-scrollbar-thumb{background:var(--ink-faint);border:2px solid var(--card);border-radius:6px}.search-panel::-webkit-scrollbar-thumb:hover{background:var(--ink-soft)}#pagefindSearch{--pagefind-ui-primary:var(--accent-1);--pagefind-ui-text:var(--ink);--pagefind-ui-background:var(--card);--pagefind-ui-border:var(--card-edge);--pagefind-ui-tag:var(--paper-deep);--pagefind-ui-font:var(--sans);padding:14px 16px 4px}#pagefindSearch mark{background:var(--highlight-soft);color:var(--ink)}#pagefindSearch .pagefind-ui__result{padding:12px 0 16px}#pagefindSearch .pagefind-ui__result-excerpt{color:var(--ink-soft)}#pagefindSearch .pagefind-ui__result-thumb{display:none}.search-hintbar{z-index:1;background:var(--card);border-top:1px solid var(--card-edge);font-family:var(--mono);color:var(--ink-faint);gap:16px;margin-top:auto;padding:8px 18px;font-size:11px;display:flex;position:sticky;bottom:0}.search-hintbar kbd{border:1px solid var(--card-edge);font-family:var(--mono);color:var(--ink-soft);border-radius:4px;margin-right:2px;padding:1px 5px}.pagefind-ui__result-link.kbd-active{outline:2px solid var(--accent-1);outline-offset:2px;border-radius:6px}.chat-fab{z-index:900;border:1px solid var(--accent-1);background:var(--accent-1);width:56px;height:56px;color:var(--ink-on-bright);cursor:pointer;border-radius:50%;justify-content:center;align-items:center;transition:transform .15s,box-shadow .15s;display:flex;position:fixed;bottom:24px;right:24px;box-shadow:0 10px 28px #0006}.chat-fab:hover{transform:translateY(-2px);box-shadow:0 14px 34px #00000073}.chat-fab:active{transform:scale(.92)}.chat-fab-hidden{display:none}.brand-row{border-bottom:1px dashed var(--sidebar-divider);justify-content:space-between;align-items:flex-start;gap:4px;margin-bottom:22px;padding-bottom:18px;display:flex}.brand-row .brand-link{flex:auto;min-width:0}.brand-menu-wrap{flex:none;position:relative}.brand-menu-btn{color:var(--sidebar-toggle-ink);cursor:pointer;background:0 0;border:1px solid #0000;border-radius:6px;padding:3px 7px;font-size:16px;line-height:1;transition:border-color .15s,color .15s}.brand-menu-btn:hover{border-color:var(--sidebar-toggle-border);color:var(--sidebar-link-hover-ink)}.brand-menu{background:var(--card);border:1px solid var(--card-edge);z-index:1100;border-radius:8px;min-width:150px;margin-top:4px;display:none;position:absolute;top:100%;right:0;overflow:hidden;box-shadow:0 12px 30px #0006}.brand-menu.open{display:block}.brand-menu-item{text-align:left;width:100%;font-family:var(--sans);color:var(--ink);cursor:pointer;background:0 0;border:none;justify-content:space-between;align-items:center;gap:14px;padding:9px 12px;font-size:13px;display:flex}.brand-menu-item:hover{background:var(--paper-deep)}.brand-menu-item-state{font-family:var(--mono);color:var(--ink-faint);font-size:11px}.brand-menu-item[aria-checked=true] .brand-menu-item-state{color:var(--accent-1);font-weight:700}.keybinds-overlay{z-index:1000;background:#080a108c;padding:14vh 20px 20px;display:none;position:fixed;inset:0}.keybinds-overlay.open{display:block}.keybinds-panel{background:var(--card);border:1px solid var(--card-edge);border-radius:12px;max-width:420px;margin:0 auto;overflow:hidden;box-shadow:0 20px 60px #00000073}.keybinds-list{padding:6px 0}.keybind-row{color:var(--ink);justify-content:space-between;align-items:center;gap:12px;padding:10px 18px;font-size:13.5px;display:flex}.keybind-row kbd{font-family:var(--mono);border:1px solid var(--card-edge);color:var(--ink-soft);background:var(--paper-deep);border-radius:4px;padding:3px 7px;font-size:11px}.chat-overlay{z-index:900;width:380px;max-width:calc(100vw - 32px);display:none;position:fixed;bottom:24px;right:24px}.chat-overlay.open{display:block}.chat-panel{background:var(--card);border:1px solid var(--card-edge);border-radius:14px;flex-direction:column;height:min(65vh,560px);display:flex;overflow:hidden;box-shadow:0 20px 60px #00000073}.chat-head{border-bottom:1px solid var(--card-edge);font-family:var(--mono);letter-spacing:.03em;text-transform:uppercase;color:var(--ink-soft);justify-content:space-between;align-items:center;padding:14px 16px;font-size:12.5px;display:flex}.chat-head-actions{align-items:center;gap:4px;display:flex}.chat-clear-btn{color:var(--ink-faint);font-family:var(--mono);letter-spacing:.03em;text-transform:uppercase;cursor:pointer;background:0 0;border:none;padding:4px 6px;font-size:10.5px}.chat-clear-btn:hover{color:var(--ink)}.chat-close{color:var(--ink-faint);cursor:pointer;background:0 0;border:none;padding:2px 6px;font-size:20px;line-height:1}.chat-close:hover{color:var(--ink)}.chat-messages{color-scheme:dark;scrollbar-width:thin;scrollbar-color:var(--ink-faint) transparent;flex-direction:column;flex:auto;gap:10px;padding:16px;display:flex;overflow-y:auto}:root[data-theme=light] .chat-messages{color-scheme:light}.chat-messages::-webkit-scrollbar{width:8px}.chat-messages::-webkit-scrollbar-track{background:0 0}.chat-messages::-webkit-scrollbar-thumb{background:var(--ink-faint);border:2px solid var(--card);border-radius:6px}.chat-messages::-webkit-scrollbar-thumb:hover{background:var(--ink-soft)}.chat-msg{white-space:pre-wrap;max-width:88%;color:var(--ink);border-radius:10px;padding:9px 12px;font-size:14px;line-height:1.5}.chat-msg-user{background:var(--accent-1-bg);border:1px solid var(--accent-1);align-self:flex-end}.chat-msg-model{background:var(--paper-deep);border:1px solid var(--card-edge);align-self:flex-start}.chat-msg-error{background:var(--accent-2-bg);border:1px solid var(--accent-2);color:var(--accent-2);align-self:flex-start}.chat-input-row{border-top:1px solid var(--card-edge);align-items:flex-end;gap:8px;padding:12px;display:flex}.chat-input-row textarea{resize:none;max-height:160px;font-size:14px;font-family:var(--sans);border:1px solid var(--card-edge);background:var(--paper);color:var(--ink);box-sizing:border-box;color-scheme:dark;scrollbar-width:thin;scrollbar-color:var(--ink-faint) transparent;border-radius:8px;outline:none;flex:auto;padding:9px 12px;line-height:1.4;overflow-y:auto}:root[data-theme=light] .chat-input-row textarea{color-scheme:light}.chat-input-row textarea::-webkit-scrollbar{width:8px}.chat-input-row textarea::-webkit-scrollbar-track{background:0 0}.chat-input-row textarea::-webkit-scrollbar-thumb{background:var(--ink-faint);border:2px solid var(--paper);border-radius:6px}.chat-input-row textarea::-webkit-scrollbar-thumb:hover{background:var(--ink-soft)}.chat-input-row textarea:focus{border-color:var(--accent-1)}.chat-input-row button{font-size:13.5px;font-weight:700;font-family:var(--sans);border:1px solid var(--accent-1);background:var(--accent-1-bg);color:var(--accent-1);cursor:pointer;border-radius:8px;flex:none;padding:9px 16px}.chat-input-row button:hover{background:var(--accent-1);color:var(--ink-on-bright)}.chat-foot{font-family:var(--mono);color:var(--ink-faint);text-align:center;padding:8px 16px 12px;font-size:10.5px}main{flex:auto;min-width:0;padding:56px 40px 120px}.wrap{max-width:var(--content-max);margin:0 auto}section.chapter{margin-bottom:96px;scroll-margin-top:26px}.chapter-head{border-bottom:3px solid var(--ink);align-items:center;gap:18px;margin-bottom:8px;padding-bottom:14px;display:flex}.chapter-num{font-family:var(--mono);background:var(--surface-inv);color:var(--highlight);letter-spacing:.03em;border-radius:6px;padding:8px 14px;font-size:32px;font-weight:600;line-height:1}.chapter-head h2{font-family:var(--serif);color:var(--ink);margin:0;font-size:30px;font-weight:600}.chapter-kicker{font-family:var(--mono);text-transform:uppercase;letter-spacing:.1em;color:var(--ink-faint);margin:14px 0 22px;font-size:12.5px}h3{font-family:var(--serif);color:var(--ink);border-left:4px solid var(--accent-3);margin:38px 0 12px;padding-left:12px;font-size:21px;font-weight:600}h4{font-family:var(--sans);color:var(--ink);text-transform:uppercase;letter-spacing:.04em;margin:22px 0 8px;font-size:15.5px;font-weight:700}p{color:var(--ink);margin:0 0 14px}p.lead{color:var(--ink-soft);font-size:17.5px}strong{color:var(--ink)}ul,ol{margin:0 0 16px;padding-left:22px}li{margin-bottom:6px}.katex{font-size:1.04em}.note{background:var(--card);border:1px solid var(--card-edge);border-left:5px solid var(--accent-3);border-radius:3px 10px 10px 3px;margin:20px 0;padding:16px 20px 16px 22px;position:relative;box-shadow:2px 3px #1b2a4a0d}.note .note-label{font-family:var(--mono);text-transform:uppercase;letter-spacing:.08em;color:var(--accent-3);align-items:center;gap:6px;margin-bottom:6px;font-size:11.5px;font-weight:600;display:flex}.note p:last-child{margin-bottom:0}.note.blue{border-left-color:var(--accent-1)}.note.blue .note-label{color:var(--accent-1)}.note.red{border-left-color:var(--accent-2)}.note.red .note-label{color:var(--accent-2)}.note.green{border-left-color:var(--accent-4)}.note.green .note-label{color:var(--accent-4)}.note.amber{border-left-color:var(--amber)}.note.amber .note-label{color:var(--amber)}.formula-box{background:linear-gradient(180deg, var(--highlight-soft), var(--paper-deep));border:1.5px solid var(--highlight);text-align:center;border-radius:8px;margin:22px 0;padding:18px 22px}.formula-box .cap{font-family:var(--mono);text-transform:uppercase;letter-spacing:.1em;color:var(--amber);text-align:left;margin-bottom:8px;font-size:11px}.formula-box .katex-display{margin:4px 0}.steps{background:var(--card);border:1px solid var(--card-edge);border-radius:10px;margin:18px 0;padding:6px 24px}.steps .step{border-bottom:1px dashed var(--card-edge);grid-template-columns:26px 1fr;gap:10px;padding:14px 0;display:grid}.steps .step:last-child{border-bottom:none}.steps .step .n{font-family:var(--mono);color:#fff;background:var(--surface-inv);border-radius:50%;justify-content:center;align-items:center;width:24px;height:24px;margin-top:2px;font-size:12px;font-weight:700;display:flex}.steps .step .body p{margin-bottom:6px}.steps .step .why{color:var(--ink-soft);font-size:13.5px;font-style:italic}.diagram{background:var(--card);border:1px solid var(--card-edge);border-radius:10px;flex-direction:column;align-items:center;gap:10px;margin:18px 0;padding:20px;display:flex}.diagram svg{max-width:100%;height:auto}.diagram .cap-txt{font-family:var(--mono);color:var(--ink-faint);text-align:center;font-size:12px}.diagram-row{flex-wrap:wrap;justify-content:center;gap:16px;display:flex}.diagram-row .diagram{flex:260px}svg .wire,svg .comp{stroke:var(--ink);stroke-width:2.6px;fill:none;stroke-linecap:round;stroke-linejoin:round}svg .comp-cap{stroke:var(--accent-1);stroke-width:3px;fill:none;stroke-linecap:round}svg 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20px}.check .check-label{font-family:var(--mono);text-transform:uppercase;letter-spacing:.08em;color:var(--accent-2);margin-bottom:8px;font-size:11.5px;font-weight:700}.check .opts{flex-direction:column;gap:6px;margin:10px 0;display:flex}.check label{cursor:pointer;border-radius:6px;align-items:flex-start;gap:8px;padding:6px 8px;font-size:14.5px;display:flex}.check label:hover{background:var(--paper-deep)}.check .feedback{border-radius:6px;margin-top:10px;padding:10px 14px;font-size:14px;font-weight:600;display:none}.check .feedback.show{display:block}.check .feedback.correct{background:var(--accent-4-bg);color:var(--accent-4)}.check .feedback.wrong{background:var(--accent-2-bg);color:var(--accent-2)}.check button.reveal-btn{font-family:var(--mono);background:var(--surface-inv);color:#fff;cursor:pointer;border:none;border-radius:5px;margin-top:4px;padding:8px 14px;font-size:12px}.check 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.p-title{font-family:var(--mono);color:var(--ink);font-size:14px;font-weight:700}.problem .p-head .p-meta{font-family:var(--mono);color:var(--ink-soft);background:var(--card);border:1px solid var(--card-edge);border-radius:20px;padding:3px 9px;font-size:11px}.problem .p-body{padding:20px 22px}.problem .p-solution{border-top:2px dashed var(--card-edge);margin-top:6px}.problem .solve-toggle{text-align:left;background:var(--surface-inv);color:#fff;width:100%;font-family:var(--mono);letter-spacing:.05em;text-transform:uppercase;cursor:pointer;border:none;justify-content:space-between;align-items:center;padding:12px 22px;font-size:12.5px;display:flex}.problem .solve-toggle:hover{background:#2b3a66}.problem .solve-toggle .arrow{transition:transform .2s}.problem .solve-toggle.open .arrow{transform:rotate(180deg)}.problem .p-solution-body{background:var(--card);padding:20px 22px;display:none}.problem .p-solution-body.show{display:block}.problem 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90px}}footer{text-align:center;font-family:var(--mono);color:var(--ink-faint);padding:40px 20px 60px;font-size:12px}@media print{@page{size:letter;margin:.25in}body.printing-single{background:#fff;font-size:11px;line-height:1.3}body.printing-single .sidebar,body.printing-single .no-print,body.printing-single footer,body.printing-single section.chapter:not(.print-target){display:none!important}body.printing-single .page{background-image:none}body.printing-single main{padding:0}body.printing-single .wrap{max-width:none;margin:0}body.printing-single section.chapter.print-target{margin-bottom:0}body.printing-single .print-target .chapter-head,body.printing-single .print-target .chapter-kicker,body.printing-single .print-target>.lead{display:none!important}body.printing-single .print-target .cheat-print-source{display:block!important}body.printing-single 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.k{color:#444}}.chapter-divider{color:var(--ink-faint);letter-spacing:.04em;text-transform:uppercase;align-items:center;gap:12px;margin:56px 0 32px;font-size:12.5px;display:flex}.chapter-divider:before,.chapter-divider:after{content:"";background:var(--grid-line-major);flex:1;height:1px}.chapter-loading{color:var(--ink-soft);align-items:center;gap:10px;margin:40px 0;font-size:13.5px;display:flex}.chapter-loading-spinner{border:2px solid var(--grid-line-major);border-top-color:var(--accent-1);border-radius:50%;width:14px;height:14px;animation:.7s linear infinite chapter-loading-spin}@keyframes chapter-loading-spin{to{transform:rotate(360deg)}}.brand-link{color:inherit;cursor:pointer;text-decoration:none;transition:opacity .15s;display:block}.brand-link:hover{opacity:.8}.pdf-viewer-toolbar{gap:8px;margin-top:22px;margin-bottom:-14px;display:flex}.pdf-viewer-btn{border:1px solid 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