Searchform doesn't show properly in Safari and Android Browser!

Hi everyone!

I’m having an issue with the native searchform of Pinboard. I’m working with WordPress 4.4.2, and it’s the first time I’m trying to personnalize so far my website by using CSS. I know some basics about CSS but that’s all. I have also a child theme.

I hope someone will understand what’s wrong with my CSS (and the CSS of Pinboard because there is the same problem on the demo version). I have this searchform, that works perfectly fine on Chrome, Firefox, IE, Opera. But it doesn’t show properly on Safari (desktop) and also the android browser of my tablet. Chrome and firefox are ok on the tablet. When I’m using Safari, the searchform, which is supposed to be on the right side of the navigation, is shifting on the left. Moreover, I can see some text inside the “bubble” of the searchbar which is not supposed to be seen.

I learned that maybe the webkit-transition might not work properly, but even with this information there’s nothing I could do to make it work.

My website is http://www.zone-blanche.com.

Thank you and forgive me if it’s not crystal clear, since english is not my native language. I will provide more informations if you need it.