I have finally started creating my first web site with ASP.NET MVC. After looking through the nice start examples, I noticed that .css files were manually included in the master page. Let’s have a look at how to use ASP.NET themes instead.
Create a themes
To create a custom theme, simply do the following:
- Right-click on your web project and choose
Add / Add ASP.NET Folder / Theme.
- This will create a folder called
App_Themesin the project root.
- Create a theme-specific folder within App_Themes, e.g. “Default”.
.cssfiles to the folder - they will be included automatically.
The theme can then be applied in two ways:
- As the default theme - add
- As a page-specific theme - add
Pagetag in the themed
The theme will now be automatically applied, which means that skin and style files will be loaded and applied to the page based on the applied theme.
I prefer the default theme approach, and apply themes only to the pages that are to use another theme. This makes it easier to switch the design of an entire app by changing a single config parameter.
Create a theme of the template css files
To convert the template application’s css files to a theme, I created a Default
theme and moved
Content/Site.css to the Default theme folder.
I then modified the web.config file to use the theme and removed the manually applied .css file from the master page.
When I then tried to run the page, it crashed with this info:
Using themed css files requires a header control on the page. (e.g. <head runat="server" />).
It turned out that the
Default.aspx file in the project root was blank and only
used to redirect the user. To make the application use the theme, I simply added
this dummy code to the page:
<html> <head runat="server"></head> </html>
This will never be displayed and doesn’t disturb the app in any way, but makes the default theme work.