The color of the grid lines can be changed in the CSS that is being called by the XSL
In the header of the XSL, you will most likely see a link to the CSS file being used to control the format of much of the content. In the example below, it is calling "theme.css" from the enigineer folder.
<html>
<head>
<link rel="stylesheet" type="text/css" href="{$xslRootDirectory}/_Themes/engineer/theme.css"/>
To change the color of the table grid lines, open this CSS (can be opened in any text editor, or xsl editor) and look for the sections for table, th, td, etc... that deal with the format of the table data, and change the various border color entries to 000000 for black.
Below is an example:
Before:
td
{
border-left-color: #FF00FF;
border-bottom-color: #FF00FF;
border-top-color: #FF00FF;
border-right-color: #FF00FF
}
After:
td
{
border-left-color: 000000;
border-bottom-color: 000000;
border-top-color: 000000;
border-right-color: 000000
}