Ignore the Finder preview - it just doesn't display SVG nicely. Your original SVG was not wrong, but it had the width and height set explicitly: width="448.8" height="261.2"
Therefore the browser was displaying it correctly, as a 448.8 x 261.2 px image in the top left corner. You can remove the display dimension from SVG using any text editor, or from Illustrator check "Responsive" when you export (not very intuitive, I must say). Without the display dimension info the browser doesn't know the size so it display as large as possible to fill the space available. Hope this makes sense 😁
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