Best Practices: CSS or Themes in ASP.NET?

Question

When should I use ASP.NET Themes, and when should I use CSS? What are the advantages or disadvantages of using one over the other?

Answer 1

Well i would recommend using both together, i use the theme to set the css classes on controls and then style them in the css files. Example:

Skin:

Css:

.Validator
{
    color: Red;   
}

.ValidationSummary
{
    font-size: 0.8em;
}

.ValidationSummary > ul
{
    list-style-type: disc;
    padding: 0 0 0 15px; 
    margin: 0;
}

.ValidationSummary > ul > li
{
    padding: 0;
    margin: 0;
    color: Red;
}