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.intro-film{max-width:400px;margin:1.8rem auto}
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/* Shared chapter outline and reading anchors. */
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/* Native mathematical layout keeps summation limits and indices aligned. A bundled math font
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/* A formula too wide for a phone has a second copy broken after its first term. */
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/* Recorded field snapshots and optional exact world equations. */
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/* Preserve legible matrix labels on narrow screens. */
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.footnote,.figure-note{font-size:.85rem;color:var(--muted)}.footnote{margin-top:-.4rem}.term-note{padding:.2em;font-size:.8em;cursor:help}
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/* Paper framing for the article; keep the reading area full-width on phones. */
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/* Field figures and films: one panel per field on white, designed for the full column. */
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/* Apparatus components: stacked disclosures, each holding its figure. */
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