<!-- <h1>This title is 5vw</h1>
<div class="box">
The window is <span class="window"></span> px.
The heading is <span class="heading"></span> px
</div> -->
<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg">
<!--
with relative unit such as percentage, the visual size
of the square looks unchanged regardless of the viewBox
-->
<rect x="0" y="0" width="100%" height="100%"/>
<!--
with a large viewBox the circle looks small
as it is using user units for the r attribute:
4 resolved against 100 as set in the viewBox
-->
<circle cx="50%" cy="50%" r="10px" fill="white"/>
</svg>
<svg viewBox="0 0 1000 1000" xmlns="http://www.w3.org/2000/svg">
<!--
with relative unit such as percentage, the visual size
of the square looks unchanged regardless of the viewBox`
-->
<rect x="0" y="0" width="100%" height="100%"/>
<!--
with a small viewBox the circle looks large
as it is using user units for the r attribute:
4 resolved against 10 as set in the viewBox
-->
<circle cx="50%" cy="50%" r="10px" fill="white"/>
</svg>
<svg viewBox="-5 -5 10 10" xmlns="http://www.w3.org/2000/svg">
<!--
The point of coordinate 0,0 is now in the center of the viewport,
and 100% is still resolve to a width or height of 10 user units so
the rectangle looks shifted to the bottom/right corner of the viewport
-->
<rect x="0" y="0" width="100%" height="100%"/>
<!--
With the point of coordinate 0,0 in the center of the viewport the
value 50% is resolve to 5 which means the center of the circle is
in the bottom/right corner of the viewport.
-->
<circle cx="50%" cy="50%" r="4" fill="white"/>
</svg>