hi Miklo, I guess you use Arthemix Bronze?
Icon for your site: This theme does not just give you a standard favicon.ico. Most sites display an icon found in the root of your site. Just place your favicon.ico in your root folder (wp-config.php should be there).
The header.php of Arthemix points to this root folder like this:
<link rel="icon" href="/favicon.ico" type="image/ico" />
<link rel="shortcut icon" href="/favicon.ico" />
Firefox will not update this icon easily, but just loading it once does the trick. Go to your site and add /favicon.ico at the end of your URL to show your icon if there is.
The yellow line dividing the posts is actually just one yellow point in images/brdrdfloat2.gif
To change the color edit this file and just change this yellow dot.
To remove it at all open style.css and look for:
.brdrd{background:#FFF url(images/brdrdfloat2.gif) repeat-y center top;}
change this to:
.brdrd{background:#FFF;}
Did it help? PLEASE BACKUP A COPY FIRST BEFORE CHANGING!!