The red and yellow standard colors of xdebug can hurt your eyes after a few hours.
http://www.designified.com/blog/article/76/restyling-xdebug-output describes how to replace the style with javascript requiring jquery.
I was looking for a more straight forward way and finally found one.
The solution is the !important tag, it overrides the existing style values. Use the following css code to avoid eye cancer when using xdebug:
.xdebug-error {
font-size: 12px !important;
width: 95% !important;
margin: 0 auto 10px auto !important;
border-color: #666 !important;
background: #ddd !important;
}
.xdebug-error th, .xdebug-error td {
padding: 2px !important;
}
.xdebug-error th {
background: #ccc !important;
}
.xdebug-error span {
display: none !important;
}
.xdebug-error_description th {
font-size: 1.2em !important;
padding: 20px 4px 20px 100px !important;
background: #ccc no-repeat left top !important;
}
.xdebug-error_callStack th {
background: #666 !important;
color: #ddd !important;
}