Tiki offers a lot of flexibility for designers to create a website to match their vision. The more familiar the designer is with Tiki, the easier it is to implement the design.
Smarty templates produce the HTML of the page. A theme can have customized versions of the default Smarty templates, to reposition page elements, etc. beyond the ability of CSS to do this, but this is discouraged as it can cause maintainability problems when files are modified in a Tiki version update.
Tiki themes, in principle, are visual skins only, produced with CSS, and don't add or change site functionality.
To implement a page layout design, there are quite a few configuration options that can be set.
Page sections can be turned on or off and the location of certain items such as buttons can be set.
Some page objects that will probably be part of the design are displayed with what are called modules. These include menus, the site logo and /or title, search form, footer links and other content, and so on. So configuring the site modules may be an important part of implementing a design.