Every website needs to look good, no matter what kind of device is used to view it. Twenty Eleven does a good job of responding to different screen sizes.
At a site I'm developing I want to use a logo instead of the blog title and motto in the header. Following some of another thread I was able to get it to look good on my desktop screen by editing the header.php and adding this stanza to style.css:
It also looks good on my 10" tablet in landscape mode, but it portrait it's a disaster, which you can see at this link.
Do you know a solution to this?