eWriter Help is regular WebHelp packaged in a single file and displayed with special viewer app. Any layout that works in WebHelp should work in eWriter Help. You can use the same skins, or dedicated eWriter skins from the Premium Pack add-on.
There are some WebHelp features you can't use in eWriter, mainly because there is no web server.
•PHP and ASP search
The HTML topic files inside eWriter Help can have either the .htm or .html extension, based on your settings for the topic file extension in your project in Configuration > Publishing Options > WebHelp > HTML Export Options. However, only these two extensions are permitted. If you set a different extension in your project (for example .php or .asp), the standard .htm extension will be used.
It is best to configure the eWriter viewer to open any links to Web pages in the user's default browser instead of in the viewer. There are no browser tabs in the eWriter viewer. If you don't set the default browser option, links to other web pages that are set to open in a new window will replace your WebHelp interface.