vinjain on "Sydney Header Image"

Hello Everyone.. Its the first time I've created a website on wordpress. I know this is a responsive theme. My website is almost complete and it looks just fine on Desktop but when open the same on mobile, the images looks too big.
For example - I am using a slider image of size 1170 X 500. It looks good on desktop but too big when open on mobile. The website url is http://www.ilampion.com/