<p dir="auto">It is dangerous to assume a number that has a distance unit omitted from it, should be pixel-based.</p>
<p dir="auto">Working within the <a href="http://www.w3.org/TR/SVG/coords.html#SVGInitialUserCoordinateSystem" rel="nofollow">SVG user space</a>, it is sometimes required that <a href="http://www.w3.org/TR/SVG/coords.html#LengthsInSVG" rel="nofollow">number values are left unitless</a>, so that they're proportionate to the user-defined matrix.</p>
<p dir="auto">The is also the additional overhead in maintaining a property (that accepts a unitless number value) <a href="https://github.com/facebook/react/blob/a8fc3b940dbe20c0c7decd19b028215b236c50a6/src/browser/ui/dom/CSSProperty.js#L24">whitelist</a>, instead of just allowing a pass-through.</p>
<p dir="auto">It's weird that <code class="notranslate">style={{margin: '42'}}</code> gets turned into <code class="notranslate">margin: 42px;</code>. I think we should only add <code class="notranslate">px</code> if the value is an actual number.</p>