Image logo in header not responsive

I have added an image for the logo in the header – but when I view in iphone – safari browser it does not respond properly it is too big and lays over the header image, drop down nav bar and even the home page title and some of the content.

Is there a specification for the size of a logo that should be used? Do you have a suggestion for fixing this little bug so that the image resizes properly in mobile safari?

Thanks Again – Lavada