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@media(max-width:640px){.sidebar{display:none;transform:none}.sidebar.open{display:flex;transform:none}}

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/* Keep each LTR equation atomic inside RTL prose. Long equations scroll locally. */
.book-content .math.inline{display:inline-block;direction:ltr;unicode-bidi:isolate;white-space:nowrap;overflow-wrap:normal;word-break:normal;vertical-align:middle;max-width:100%;overflow-x:auto;overflow-y:hidden;line-height:1.6;padding:2px 3px}
.book-content .math.inline .katex{white-space:nowrap;overflow-wrap:normal;word-break:normal}
/* PDF glyph coordinates are LTR, independently of the document's language. */
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/* A quiet, consistent motion language for the reader and experiments. */
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#search-input:focus,#search-input:focus-visible,#search-open:focus,#search-open:focus-visible{outline:0;outline-offset:0;box-shadow:none;border-color:var(--line)}
body,.topbar,.sidebar,.book-box,.lab,.lab-heading,.lab-explain,dialog{transition:background-color .25s ease,color .25s ease,border-color .25s ease}
button,a,summary{transition:background-color .18s ease,color .18s ease,border-color .18s ease,box-shadow .2s ease,transform .2s var(--motion-ease)}
.primary:hover,.secondary:hover,.chapter-downloads a:hover{transform:translateY(-1px);box-shadow:0 5px 14px #173d3b12}
.primary:active,.secondary:active,.icon-btn:active,.lab-select:active{transform:scale(.97)}
.lab-select:hover{border-color:var(--green);transform:translateY(-2px)}
.lab-select.active{box-shadow:0 2px 12px #173d3b08;transform:translateY(0)}
.lab-chart{position:relative;isolation:isolate}
.lab-chart path,.lab-chart rect,.lab-chart circle{transition:fill .24s ease,stroke .24s ease,opacity .24s ease}
.lab-chart svg{transform-origin:center}
input[type=range]::-webkit-slider-thumb{transition:transform .16s ease,box-shadow .16s ease}
input[type=range]:active::-webkit-slider-thumb{transform:scale(1.12)}
.nav-btn.active:after{animation:nav-underline .24s var(--motion-ease);transform-origin:right}
.chapter-exports summary::marker{color:var(--green)}
#search-results{transform-origin:top}
dialog::backdrop{animation:modal-backdrop-in .23s ease-out both}
dialog.is-closing::backdrop{animation:modal-backdrop-out .17s ease-in both}
@keyframes modal-backdrop-in{from{background-color:#142c2900;backdrop-filter:blur(0)}to{background-color:#142c2966;backdrop-filter:blur(4px)}}
@keyframes modal-backdrop-out{from{background-color:#142c2966;backdrop-filter:blur(4px)}to{background-color:#142c2900;backdrop-filter:blur(0)}}
@keyframes nav-underline{from{transform:scaleX(.2);opacity:.3}to{transform:scaleX(1);opacity:1}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}.primary:hover,.secondary:hover,.lab-select:hover,.chapter-downloads a:hover{transform:none}}

#search-results{overflow:hidden}

.lab-table-scroll{overflow-x:auto;margin:14px 0;max-width:100%}.lab-table-scroll table{width:100%;border-collapse:collapse;font-size:.86rem}.lab-table-scroll th,.lab-table-scroll td{padding:8px 12px;border-bottom:1px solid #d9dfd9;text-align:center;min-width:65px}.lab-chart svg{overflow:hidden;display:block;width:100%;height:auto;max-height:420px}.hero-equation{font-size:16px;letter-spacing:.02em}.byline strong{line-height:1.8}.lab-controls select{max-width:100%;min-width:0}.lab-explain{overflow-wrap:anywhere}.book-content .math.display{overflow-x:auto}.lab-question{line-height:2}.lab-stats strong{font-variant-numeric:tabular-nums}

/* Questions remain visible; each explanation opens independently. */
.selftest-list{padding-inline-start:1.65em;margin:24px 0;counter-reset:none}.selftest-list>li{padding:0 8px 18px;margin-bottom:20px;border-bottom:1px solid var(--line)}.selftest-list>li::marker{color:var(--green);font-weight:600}.selftest h3{font-size:1.06em;margin:0 0 10px;color:var(--ink);line-height:1.8}.selftest-question>:first-child{margin-top:0}.selftest-answer{margin-top:14px;border:1px solid var(--line);border-radius:6px;background:var(--paper)}.selftest-answer>summary{cursor:pointer;padding:11px 16px;color:var(--green);font-size:.85em;font-weight:500}.selftest-answer>summary:focus-visible{outline:2px solid var(--gold);outline-offset:3px}.selftest-answer[open]>summary{border-bottom:1px solid var(--line)}.selftest-answer>div{padding:3px 16px 12px;min-width:0}.selftest-answer .math.display{max-width:100%;overflow-x:auto}.selftest-question{overflow-wrap:anywhere}@media print{.selftest-answer>div{display:block!important}.selftest-answer>summary{display:none}}

.lab-guide{margin:12px 0 20px;border:1px solid var(--line);border-radius:5px}.lab-guide summary{cursor:pointer;padding:9px 13px;font-size:12px;color:var(--green)}.lab-guide>div{padding:0 14px}.lab-guide li{padding:5px 0;font-size:12px;line-height:2}.lab-reset{font-size:11px;white-space:nowrap}

.topbar nav{min-width:0;overflow-x:auto;scrollbar-width:none}.topbar nav::-webkit-scrollbar{display:none}.nav-btn{flex-shrink:0;white-space:nowrap}.resource-list{padding:0 40px 45px;display:grid;gap:22px}.resource-card{border:1px solid var(--line);background:var(--paper);border-radius:8px;padding:24px}.resource-heading{display:flex;align-items:center;gap:17px;margin-bottom:20px}.resource-number{width:43px;height:43px;display:grid;place-items:center;background:var(--soft);color:var(--green);border-radius:50%;flex-shrink:0}.resource-heading h2{font-size:21px;line-height:1.7;margin:3px 0}.resource-heading .eyebrow{font-size:10px}.resource-downloads{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px}.resource-downloads a{display:flex;flex-direction:column;gap:8px;border:1px solid var(--line);border-radius:5px;padding:13px;font-size:12px;color:var(--green);transition:background .18s,border-color .18s}.resource-downloads a:hover{background:var(--soft);border-color:var(--green)}.resource-downloads small{color:var(--muted);font-size:10px}.resource-actions{display:flex;flex-wrap:wrap;justify-content:space-between;gap:12px;margin-top:20px;font-size:11px;color:var(--muted)}.resource-actions button{color:var(--green);font-size:11px}@media(max-width:850px){.resource-list{padding:0 25px 30px}.topbar nav{gap:12px}.nav-btn{font-size:11px}}@media(max-width:640px){.topbar{gap:10px}.topbar nav{flex:1;gap:10px}.nav-btn{font-size:10px}.resource-list{padding:0 18px 25px}.resource-card{padding:18px}.resource-heading h2{font-size:18px}.resource-downloads{grid-template-columns:1fr}.resource-actions{flex-direction:column;align-items:flex-start}.resource-downloads a{flex-direction:row;align-items:center;justify-content:space-between;gap:8px}}