Improve retrieval of width and height

[Faterou]

Originally reported by: Francis Guérin (Bitbucket: Faterou, GitHub: Faterou)

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We can follow this code to make sure it works with any browser.

var w=window,
d=document,
e=d.documentElement,
g=d.getElementsByTagName('body')[0],
x=w.innerWidth||e.clientWidth||g.clientWidth,
y=w.innerHeight||e.clientHeight||g.clientHeight;

Taken from here

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• Bitbucket: https://bitbucket.org/sylvainhalle/cornipickle/issue/26