How can I modify the search bar behavior on Dawn theme?

[Dabou]

Hello, i would like to change how the search field works, so instead of the word Search... getting smaller and moved to the top left, when someone would type just 1 letter, the word would disappear. 
(This change should apply to the header search bar, and the bar in the search page)
Obs: i would like to edit in the main code, instead of adding extra code.


Website: Dazzilia.com

Thank you.

[Dabou]

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