How to remove the inner white border 1px on canvas Fabric JS?

I don't see it on a desktop display, but on mobile, it is shown (Only on Android, iPhone is ok).

My canvas parts.
HTML:

<canvas id="c_mobile"></canvas>

CSS:

#c_mobile{
border: 1px solid #cc1118;
padding: 0;margin: 0;}

Screenshot:

Please, help! Thanks for attention!