The viewBox attribute defines the position and dimension, in user space, of an SVG viewport.
The value of the viewBox attribute is a list of four numbers separated by whitespace and/or a comma: min-x, min-y, width, and height. min-x and min-y represent the smallest X and Y coordinates that the viewBox may have (the origin coordinates of the viewBox) and the width and height specify the viewBox size. The resulting viewBox is a rectangle in user space mapped to the bounds of the viewport of an SVG element (not the browser viewport). When an SVG contains a viewBox attribute (often in combination with a preserveAspectRatio attribute), a transform stretches or resizes the SVG viewport to fit a particular container element.