Composition in Color A, 1917, by Piet Mondrian, rendered in SVG

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After circles, rectangles are probably the easiest element to draw in , requiring just one more attribute to complete them. The basic syntax for rectangles requires an x position, y position, width and height:

<svg xmlns="" viewBox="0 0 80 80">
	<rect x="20" y="20" width="40" height="40"/>

There’s a few things to note immediately:

  • unlike circles, rectangles are drawn from their top left corner (the supplied x and y coordinates).
  • like most other elements, rectangles lacking a fill are black by default.
  • the rectangle element is “closed inside itself” with a slash (/)
  • like all other elements, rectangles that appear later in the code will appear on top of previous elements if they overlap.
  • despite the impression this article’s title may have provided, there is no distinct “square” element in SVG: squares are just rectangles with equal values for their width and height.

Borders & Corners

Like all other shapes in SVG, <rect> elements can be provided with a border (referred to as stroke in SVG):

<rect x="20" y="20" width="40" height="40" 
stroke="tomato" stroke-width="5" >


In CSS you can use border-radius to round the visible corners of elements. For SVG rectangles, it’s the attributes rx and ry:

<rect x="20" y="20" width="40" height="40" stroke="tomato" stroke-width="5" rx="5" ry="5" />

Which creates:

However, unlike border-radius, rx and ry always affects all corners of the element simultaneously and equally: there’s no way to put a curve on one corner of an SVG rectangle and not on the rest. You can give the attributes different values for more extreme appearances, to create barrel shapes for example:

…but in most cases both attributes will have the same value, producing perfect quarter-circle corners. To shortcut this, you can provide just the value of rx:

<rect x="20" y="20" width="40" height="40" rx="5"  />

The Biggest Rectangle of Them All: Styling The Viewport

In most editors, the background of an SVG drawing appears to be white. That’s not actually true: it’s transparent, and naturally alpha-masked, meaning that it will look perfect when placed as an image or inline SVG against any on an HTML page.

The natural response to needing a “canvas” of a different color in SVG is to draw an enormous rectangle that covers the entire SVG viewport. But that’s usually a bad idea: not only does it add another element to the page, it also complicates rendering. Instead, simply style the SVG element itself.

svg { background: #fcedd6; }

It’s even possible to place a border-radius on the SVG element, as I did with the Captain America shield example I created for the circle article. This can come in handy if you’re trying to give the impression of the entire SVG having a circular drop shadow, for instance.

The recreation of Piet Mondrian's work was partly inspired by Jenn Schiffer, who has written an excellent series on recreating artworks using web technologies.

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