HooThemes

Animated search form with Pure CSS3, replace search form with custom CSS styles.

Search Box

Animated search form with Pure CSS3, replace search form with custom CSS styles.

Apsara Aruna

This is customized your search form to the full screen search box.
How to use it 
*Only you have to do after the installation, add custom link to you menu and type url to ‘#search’. you can put Link text as you wish.
Also see my other plugins 
* <a href="https://wordpress.org/plugins/widget-youtube-subscribtion/" title="Easy Subscribe Button Widget" rel="ugc">Easy Subscribe Button Widget</a> 
* <a href="https://wordpress.org/plugins/embed-page-facebook/" title="Easy Embed Page Widget" rel="ugc">Easy Embed Page Widget</a> 
* <a href="https://wordpress.org/plugins/browser-scroll-bar/" title="Browser Scroll Bar" rel="ugc">Browser Scroll Bar</a>

Easy Full Screen Search

This is customize you search form to full screen search box.

Search Box vs Easy Full Screen Search