From Legacy Wiki
Example
The 'color' parameter is the background color. The 'border' parameter is the border color. The background color should be a darker shade of the border color. If the background color is not dark, the white text may be difficult to read. In that case, use a black text by setting the 'text' parameter. The first unnamed parameter is the text to appear in the box.
{{Color box|color=#144f1d|border=#2f8f2f|I made a colorful box!}}
{{Color box|color=#205|border=#60b|And this one is purple.}}
{{Color box|color=#c0f|border=#a0f|text=#000|Too light}}