Custom CSS Stylesheets for Calibre's Viewer

body {color:rgb(0,0,0);
background-color:rgb(174,174,174);
text-align:justify;
line-spacing:1.8; 
margin-top:0px;
margin-bottom:4px;
margin-right:50px;
margin-left:50px;
text-indent:3em;}
h1, h2, h3, h4, h5, h6
{color:black;
text-align:center;
font-style:italic;
font-weight:bold;}

You have an error in there. I was testing out a completely different color scheme (harking back to the "good old" MS-DOS days), when I used WHITE on BLUE background for my console (worked better then, with fixed pitch, large fonts :-). In your code above, you need to add a ':' after the body 'color' name. Without it, the body (text) color is ignored. It still works for what you want, because the default color is black. But it doesn't work if you try to set it to anything else. Not necessarily pleasing to use, but as another example, here's my "white on blue" style:

body {
color: rgb(255,255,255);
background-color:rgb(0,0,255);
text-align:justify;
line-spacing:1.8;
margin-top:0px;
margin-bottom:4px;
margin-right:50px;
margin-left:50px;
text-indent:2em;
}
h1, h2, h3, h4, h5, h6 {
color:white;
text-align:center;
font-style:italic;
font-weight:bold;
}