Nginx offers to download SVG instead of showing it

I fixed it. I added to /etc/nginx/mime.types

image/svg+xml svg svgz;

Then I checked that server responses correctly

wget -O - -S http://proximax.ru/media/content/final/avW30U.svg > /dev/null
..
Content-Type: image/svg+xml
..

Also I turned off other virtual spaces for be clear.

The of your image is noted as application/octet-stream which a browser can only offer to download as it does not know how to interpret it.

From your index.html file it is clear that you were playing around with variations of the MIME-type, and it is unclear whether the standard requires image/svg or image/svg+xml (or standards being what they are, something else entirely).