All you have to do now is tell your site to use your new theme - This is defined in the **mysite/_config.php** file
:::php
SSViewer::set_theme('mythemename');
Go to yoursite.com/?flush=1 and check it out. You should be using your new theme! Not really that awesome or amazing is
it? Next we need to add some CSS Magic!
See [Templates](/reference/themes) for more information about templates.
### CSS Files
By standard SilverStripe uses 3 CSS Files for your site -
***layout.css** contains the layout and design of the site
***typography.css** contains the styling for the text/fonts/links (used in both front and back ends)
***form.css** styling for forms.
You can add more stylesheets using the template tag `<% require themedCSS(filename) %>`, which will load filename.css from
your css directory.
Note: If you're using a default install of Silverstripe and notice that you're getting layout.css, typography.css and
forms.css included without asking for them, they may be being called on lines 21-23 in mysite/code/Page.php. Remove
these three Requirements::themedCSS lines, and you will be free to add your own styles.
## Dividing your site the correct way!
Most Web page designers 10 years ago used a table-based layout to achieve a consistent look. Now, (Thankfully) there's a
different way to achieve the same look.
Using CSS and tags (including `DIV`s) reduces markup code, speeds up page downloads, separates content from
its visual presentation, and brings your code closer to web standards compliance--all while making your website more
appealing to search engine spiders.
For layout we tend to use `DIV` tags as the `DIV` tag defines a division/section in a document.
Let's have a look at part of a Page.ss for the main layout elements defining a 2 column layout.
:::ss
<divid="Container">
<divid="Header">
<!-- Header -->
</div>
<divid="Navigation">
<!-- The Main Site Nav -->
</div>
<divid="Layout">
<!-- The whole site content has to sit inside here! Anything you want to sub template (eg each page will be different, needs to be contained in $Layout. This calls the file /Layout/Page.ss or anyother sub page template -->
$Layout
</div>
<divid="Footer">
</div>
</div>
As you can see we normally wrap the site in a container. For this we use the ID 'Container'. Then we divide the main
template into sections.
:::ss
<divid="Header"><!-- markup goes here --></div>
We have the Header section which includes things like any banner images/ mastheads/ logos or any stuff that belongs at
the top of the page, This might vary on the design of the page
:::ss
<divid="Navigation"><!-- markup goes here --></div>
Next is a division for the main navigation. This may contain something like:
