Apply a Theme to all sub sites:(works for MOSS 2007 only, not WSS 3.0)
  1. Change the top site to the theme of your choice using the normal method in Site Actions > Site Settings > Site Theme.
  2. Navigate to the top site to see the newly applied theme.
  3. View the HTML source of the SharePoint page using the theme you want.
  4. Look for a link tag containing the .css file for the applied theme.  It will look something like this:
    <link rel="stylesheet" type="text/css" id="onetidThemeCSS" href="/apps/afe/_themes/Belltown/Bell1011-65001.css?rev=12%2E0%2E0%2E4518"/>
  5. Copy the href value to your clipboard or to a text file if you like.  It should look something like:
  6. On your top level site, go to the Site Actions > Site Settings > Master Page screen.
  7. Scroll to the bottom where the Alternate CSS URL section is.  Select the "Specify a CSS file..." option.
  8. Paste the path copied from the href above into the text box.
  9. Check the Reset all sub-sites to inherit this alternate CSS URL option.
  10. Click OK.
  11. Navigate to your sub-sites and verify the theme has been applied.