Ouch: Truncated Header

My ‘modified’ header image looks the way it’s supposed to on my montor screen if the resolution is 1024×760 , but at 800×600 the image is truncated (at the right side).

I’m using Theme Nerima Daikon 3c, which didn’t come with a header image. Although the rest of the page(s) adjust automaticlly when I move from one resolution to the the other (sidebars, content text, etc.)the header image doesn’t ‘shrink to fit’ like the other elements do.

Here’s the css style code for the header image:
‘#header {
height: 105px;
margin-top: 10px;
padding: 0px;
color: #ffffff;
background-image:url(‘./images/jjheader-r.png’);
background-repeat:no-repeat
}’

Anything in this code I can change or add, so that the header ‘adjusts’ with the rest of the page on a lower res monitor?

If it helps to see my site, the URL is: https://www.jayjerome.com.