Move Scroll Down Arrow up

Good Afternoon. I was wondering if you could help me. The desktop version of my site is 100s however on Mobile Devices the Scroll Down is too far down on the header image that you don't see it. I would like to move this up, or if there is away to change the size of header image just for Mobile devices only so they can see the scroll down arrow. Secondly I just want to change the colour of my blog post titles and dates etc on the front page only. Thank you in advance :)