:root{--ink:#172039;--muted:#68758a;--purple:#6366f1;--line:#e1e6ef;--wash:#f2f5fa;--green:#16824b;--amber:#9b4b12}*{box-sizing:border-box}body{margin:0;background:var(--wash);color:var(--ink);font:16px/1.65 'DM Sans',system-ui,sans-serif}button,input,select{font:inherit}button,a,input,select{touch-action:manipulation}button,a{ -webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{opacity:.5;cursor:default}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #b5b5ff;outline-offset:4px}a{color:#4f46e5}.top{background:#10182b;color:white}.top-inner{max-width:1180px;margin:auto;padding:20px 28px;display:flex;justify-content:space-between;gap:18px;align-items:center}.brand{display:flex;align-items:center;gap:12px;color:inherit;text-decoration:none;font-weight:600;font-size:20px}.brand img{width:30px;height:38px}.top nav{display:flex;gap:18px;font-size:13px}.top nav 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/* Equation transposition: pointer-following terms and inverse-operation receipts. */
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