You'll need 2 nested elements in order to have 4 pseudo-elements, one for each corner. Then, you just have to give pseudo-elements the same background color as the background of your page, and rotate them.

thanks for your help HugoGiraudel & Odd_E ..

is there another method to hide corners without make its like background color ?

because may be i'll set image as background page .. !!

in this case { cut1 & cut2 } will appear !!

http://codepen.io/wolfcry911/pen/remhu