Header image does not stretch across the whole header

I have just created a website with maximum width of 1310 pixels and have adjusted the height of the header to be 190 pixels.

However, when I upload a header image which is exactly 1310 x 190 pixels, it does not stretch across the whole header. There seems to be a margin on either side and below the image. Please see it at:

http://27.121.64.167/~vsjkhxsd/

I had a similar problem a while ago and was told to insert the following into quick CSS. Unfortunately that hasn’t quite fixed the problem

.html_header_top.html_logo_center .logo {left: auto;
-webkit-transform: translate(0, 0);
-moz-transform: translate(0, 0);
-ms-transform: translate(0, 0);
transform: translate(0, 0);
}

Many thanks
Ivana