How to position my svg image to the center of browser - css

Question

I generated a simple svg image and loaded it to Chrome. Meant to position it to the center of browser(even when the browser resizing), but so far have failed on this.
Have referred to some articles about viewport/viewbox setting, and some Q&As on this site(https://stackoverflow.com/questions/8639383/how-do-i-center-an-svg-in-a-div;https://stackoverflow.com/questions/13373169/align-svg-to-center-of-screen), but haven't got it done. Maybe I missed something, since I am very new to this.
Here is the full code for this svg image:
<svg
xmlns="http://www.w3.org/2000/svg"
xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
width="100%"
height="100%"
viewBox="0 -700 1080 1920"
preserveAspectRatio="xMidYMid meet"
version="1.1"
id="mysvg"
>
<g
id="group" >
<circle
r="500"
style="fill:#ffb721;fill-opacity:1"
cy="0"
cx="0"
id="path" />
<circle
style="fill:#f71c17;fill-opacity:1;"
id="path2"
cx="0"
cy="0"
r="250" />
</g>
</svg>
I expect this image could stay at the center of the browser, even during browser resizing.

Answer 1

I think this is what you want?
The SVG will be position in the center even the browser resized and scroll
ON GLOBAL CSS
CSS:
#container {
top: 50%;
left: 50%;
position: fixed;
transform: translate(-50%, -50%);
}
INSIDE SVG
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 439.29 439.29" width="100%" height="100%">
<g id="group">
<circle cx="219.64" cy="219.64" r="219.64" style="fill: #ffb721" id="path"/>
<circle cx="219.64" cy="219.64" r="108.32" style="fill: #f71c17" id="path2"/>
</g>
</svg>

Answer 2

Your SVG needs a little modification to center it in the ViewBox.
body {
min-height: 100vh;
display: flex;
align-items: center;
justify-content: center;
}
.container {
width: 300px;
height: 300px;
background-color: rgba(red, .3);
}
<div class="container">
<svg
xmlns="http://www.w3.org/2000/svg"
xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
width="100%"
height="100%"
viewBox="-540 -960 1080 1920"
preserveAspectRatio="xMidYMid meet"
version="1.1"
id="mysvg"
>
<g
id="group" >
<circle
r="500"
style="fill:#ffb721;fill-opacity:1"
cy="0"
cx="0"
id="path" />
<circle
style="fill:#f71c17;fill-opacity:1;"
id="path2"
cx="0"
cy="0"
r="250" />
</g>
</svg>
</div>