fabricjs will convert:
// this DOM structure
<div id="wrapper">
<canvas id="c"></canvas>
</div>
// to this:
<div id="wrapper">
<div class="canvas-container">
<canvas class="upper-canvas"></canvas>
<canvas class="lower-canvas" id="c"></canvas>
</div>
</div>
... see this explanation
Because of the way fabric js wraps a canvas element, how do you keep a canvas horizontally centered.
here is similar question. here is a fiddle test