Cross Browser Compatibility Issues with Menu Bar

Hi Everyone,

i’m using the free responsive theme and it’s great! But i did some css changes, especially in regards to my Menu bar. Now i’m facing Cross Browser Compatibility Issues.
My website is : https://www.silverhounddogwalking.com
When accessing my website through safari, it views great, but all the other browsers .. it just looks awful. And i suppose there is somewhere some code within my css child theme modification.
If you could please point me to the right direction, that’d be great!!

Thanks so much in advance.