Shadow DOM

<SvgIn /> renders the sanitized SVG directly into the page (the light DOM), so a page-wide CSS rule that happens to match one of its elements reaches straight in - and its own inline <style>, if it has one, reaches straight out. <SvgInShadow /> renders into a shadow root instead, closing that door in both directions. Both cards below sit inside the same container, with the same leaking page rule applied to it.