Catch Responsive Mobile width and Color Footer RSS

Hello from Germany, my english is not so good but i hope i can explaine my question. I use for my website www.landhauskunst.de the free theme catch responsive as a childtheme and made some featuring. i dont know how to change the color of the rss and latest post? i also dont know, why in the mobile view on smartphone, the width of the site is a little bit too wide so i can scroll left an right. Can someone help me please! Thx