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3rem;columns:2;column-gap:3rem}.concept-list>li{break-inside:avoid;margin-bottom:1.2rem;padding-left:.3rem;font-size:.9rem}.concept-list p{margin:.4rem 0 0;color:var(--muted)}.ladder-number{display:inline-block;font-family:monospace;color:var(--blue);margin-right:1rem}.project-brief{padding:1.5rem;max-width:85ch}.project-brief p{color:var(--muted);font-size:.9rem}.project-brief pre{max-width:100%;overflow:auto;font-size:.8rem;padding:1rem;border:1px solid var(--line)}.reading-list{counter-reset:paper;list-style:none;padding:0}.reading-list li{position:relative;padding:1.6rem 0 1.6rem 3.5rem;border-bottom:1px solid var(--line)}.reading-list li::before{counter-increment:paper;content:counter(paper,decimal-leading-zero);position:absolute;left:0;top:1.6rem;color:var(--blue);font-family:monospace}.reading-list h3{margin:.6rem 0;font-size:1.2rem}.reading-list p{color:var(--muted);font-size:.9rem;margin-bottom:0;max-width:80ch}.book-breadcrumb{display:flex;gap:.8rem;padding:2rem 0 0;font-size:.8rem;color:var(--muted)}.book-header{max-width:900px;padding:3rem 0}.book-header h1{font-size:clamp(2.6rem,5.4vw,4.6rem)}.book-layout{display:grid;grid-template-columns:250px minmax(0,1fr);gap:3rem;align-items:start}.book-sidebar{position:sticky;top:105px;max-height:calc(100dvh - 125px);overflow:auto;font-size:.8rem;padding-right:1rem}.book-sidebar h2{font-size:1.1rem}.book-sidebar ol{list-style:none;padding:0;margin:0 0 2rem}.book-sidebar li{margin:.7rem 0}.book-sidebar .card-kicker{margin:1.5rem 0 .7rem;line-height:1.6}.book-sidebar>a{display:block;margin-top:1rem}.book-main{min-width:0}.book-part{padding:3rem 0 1rem}.book-part>h2{font-size:1.8rem}.chapter-outline{padding:1.8rem 0;border-bottom:1px solid var(--line);scroll-margin-top:110px}.chapter-heading{display:flex;gap:1rem}.chapter-number{color:var(--blue);font-family:monospace;font-size:1rem;padding-top:.1rem}.chapter-heading h3{font-size:1.4rem;margin-bottom:.6rem}.chapter-heading p{margin-bottom:0}.chapter-sections{list-style:none;padding:0;margin:1.5rem 0}.chapter-sections li{padding:.7rem 0;border-top:1px solid var(--line);color:var(--text);font-size:.95rem}.chapter-sections span{display:inline-block;min-width:4.3rem;font-family:monospace}.chapter-status{font-size:.8rem;color:var(--muted);border-left:2px solid var(--accent);padding-left:1rem;max-width:70ch;margin-bottom:0}.source-card{margin:1rem 0;padding:1.5rem;border:1px solid var(--line);border-radius:12px;background:var(--surface)}.source-card p{color:var(--muted);font-size:.9rem}.source-card h3{margin-top:.7rem}.book-pagination{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(220px,100%),1fr));gap:1rem;padding:3rem 0;margin-top:3rem;border-top:1px solid var(--line)}.book-pagination a{padding:1rem;border:1px solid var(--line);border-radius:10px;text-decoration:none;min-width:0}.book-pagination strong,.book-pagination span{display:block}.book-pagination strong{font-size:.9rem;font-weight:500;margin-top:.7rem}.learning-details summary:hover{color:var(--blue)}
@media(max-width:900px){.learning-hero{gap:2rem}.learning-cover{min-height:370px;padding:1.5rem}.learning-cover strong{font-size:2rem}.book-layout{grid-template-columns:210px minmax(0,1fr);gap:1.5rem}.book-card-body{padding:1.2rem}.learning-stats div{display:block}.learning-stats span{display:block}}
@media(max-width:650px){.learning-hero{grid-template-columns:1fr;padding:3rem 0}.learning-hero h1{max-width:18ch}.learning-cover{display:none}.learning-start,.roadmap-grid,.book-grid,.book-layout{grid-template-columns:1fr}.learning-stats{grid-template-columns:repeat(2,1fr)}.learning-stats strong{font-size:1.7rem}.concept-list{columns:1}.book-sidebar{position:static;max-height:none;border-bottom:1px solid var(--line);padding-bottom:1.5rem}.book-header{padding:2.5rem 0 1.5rem}.book-spine{width:36px}.learning-note{padding:1.3rem}.learning-details summary{padding:1rem}.chapter-heading h3{font-size:1.25rem}}
@media print{.site-header,.site-footer,.learning-jumps,.book-sidebar,.book-pagination,.filter-bar,.learning-cover{display:none}.book-layout,.learning-start,.book-grid,.roadmap-grid{display:block}.book-card,.learning-note,.chapter-outline{break-inside:avoid}.page-shell{padding:0}.learning-hero{display:block;padding:1rem 0}.learning-stats{padding:.5rem 0}.book-part,.section{padding:1rem 0}.book-header{padding:1rem 0}}
/* Authored book reader: all dimensions stay within the existing page shell. */
.library-volume{grid-template-columns:minmax(230px,.8fr) minmax(0,1.5fr);padding-top:1rem}.library-volume h2{font-size:clamp(2rem,4vw,3.4rem);line-height:1.1}.library-volume h2 a{text-decoration:none}.library-volume .learning-cover{transform:rotate(-2deg);text-decoration:none}.learning-cover img{width:100%;height:auto;margin:1.5rem 0;border-radius:8px}.learning-cover strong{font-size:clamp(1.9rem,3vw,2.8rem)}.book-byline{color:var(--text);font-size:1rem}.book-breadcrumb{flex-wrap:wrap}.reader-prose{max-width:850px}.reader-prose p{line-height:1.85}.reader-prose .book-part>h2{margin-top:2rem;font-size:1.7rem}.reader-prose .book-part>h2:first-child{margin-top:0}.book-figure{margin:1.5rem 0;border:1px solid var(--line);border-radius:14px;overflow:hidden;background:var(--surface)}.book-figure img{display:block;width:100%;height:auto}.book-figure figcaption{font-size:.8rem;line-height:1.6;color:var(--muted);padding:1rem}.lesson-flow svg{width:100%;height:auto;color:var(--blue);display:block}.lesson-flow rect{fill:var(--elevated);stroke:var(--line)}.lesson-flow text{fill:var(--text);font-size:18px;font-family:inherit}.lesson-flow path{stroke:currentColor;fill:none;stroke-width:2}.lesson-flow marker path{fill:currentColor}.book-equation{padding:1.5rem;border-left:3px solid var(--accent);background:var(--surface);font-family:Georgia,serif;font-size:1.35rem;line-height:1.8;overflow-wrap:anywhere}.symbol-table{width:100%;border-collapse:collapse;margin-top:1.5rem;font-size:.9rem}.symbol-table caption{text-align:left;color:var(--muted);padding:.6rem 0}.symbol-table th,.symbol-table td{text-align:left;padding:.8rem;border-bottom:1px solid var(--line);overflow-wrap:anywhere}.symbol-table th{font-weight:600}.symbol-table th:first-child{width:25%}.book-code,.book-output{font-family:monospace;font-size:.85rem;line-height:1.7;padding:1.3rem;border:1px solid var(--line);border-radius:12px;overflow:auto;max-width:100%;background:var(--surface);color:var(--text)}.book-output{border-left:3px solid var(--blue)}.reader-prose .chapter-outline{padding:0;scroll-margin-top:120px}.reader-prose .chapter-sections{padding:0 1.3rem}.toc-chapters{margin-top:1.5rem;font-size:.85rem}.toc-chapters summary{cursor:pointer;color:var(--muted)}.toc-chapters h4{margin-top:1.2rem}.toc-chapters ol{padding-left:1.2rem}.toc-chapters li{margin:.7rem 0}.book-interactive{padding:1.5rem;background:var(--surface);border:1px solid var(--blue);border-radius:14px;margin-top:2rem}.book-interactive svg{display:block;width:100%;height:auto;margin:1rem 0}.book-interactive svg text{fill:var(--text);font-family:inherit;font-size:14px}.lab-controls{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(230px,100%),1fr));gap:1rem}.lab-controls[hidden]{display:none}.lab-controls label{font-size:.85rem}.lab-controls input{display:block;width:100%;margin-top:1rem;accent-color:var(--blue)}.lab-controls output{font-weight:700;color:var(--blue)}.lab-axis{stroke:var(--muted);stroke-width:2;fill:none}.lab-threshold{stroke:var(--accent);stroke-width:1.5;stroke-dasharray:5 5;fill:none}.lab-trace{stroke:var(--blue);stroke-width:2;fill:none}.lab-field,.lab-node circle{fill:var(--elevated);stroke:var(--muted)}.lab-object{fill:var(--blue);opacity:.75}.book-interactive [data-lab-result]{font-size:.9rem;overflow-wrap:anywhere}.reader-prose section{scroll-margin-top:110px}
@media(max-width:650px){.library-volume{grid-template-columns:1fr}.library-volume .learning-cover{display:flex;max-width:330px;margin:0 auto 1.5rem;min-height:0}.library-volume .learning-cover strong{font-size:2rem}.library-volume .learning-cover img{max-height:170px;object-fit:contain}.book-sidebar nav ol{display:flex;flex-wrap:wrap;gap:.3rem 1rem;margin-bottom:1rem}.book-sidebar nav li{margin:.2rem 0}.book-figure{overflow-x:auto}.book-figure img{min-width:520px}.lesson-flow svg{min-width:480px}.book-interactive{padding:1rem}.book-interactive svg{min-height:170px}.book-equation{font-size:1.15rem;padding:1rem}.book-code{font-size:.78rem;padding:1rem}.book-breadcrumb{font-size:.75rem}.book-figure figcaption{position:sticky;left:0;min-width:0}.book-figure::after{content:'Scroll diagram horizontally for detail';display:block;padding:0 1rem .8rem;font-size:.7rem;color:var(--muted)}.book-figure figcaption{max-width:calc(100vw - 4rem)}}
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.lab-viewport{overflow-x:auto;max-width:100%}@media(max-width:650px){.lab-viewport svg{min-width:500px}}
@media(min-width:651px) and (max-width:900px){.book-layout{grid-template-columns:1fr}.book-sidebar{position:static;max-height:none;border-bottom:1px solid var(--line);padding-bottom:1.5rem}.book-sidebar nav ol{display:flex;flex-wrap:wrap;gap:.3rem 1rem;margin-bottom:1rem}.book-sidebar nav li{margin:.2rem 0}}
.book-figure:focus-visible,.lab-viewport:focus-visible{outline:2px solid var(--blue);outline-offset:3px}

.derivation-steps{padding-left:1.5rem}.derivation-steps li{padding-left:.4rem;margin:1rem 0;line-height:1.85}.derivation-steps li::marker{color:var(--blue);font-weight:600}