CSS Soliloquy styling problems – Gantry Titania Theme

Hi there

I need to change the position and size of my soliloquy but after hours of playing with the child theme I can’t get it right. Main problem is that the slider isn’t centred.

formacionredrock

I’ve reverted to the original theme code which is what shows now but I need the slider to be 850px by 260px (or something similar) and I want a margin of 15px between the header and the slider. When I mess with the code it aligns partially to the left.
Maybe my image sizes are messing it up but the theme as an option to crop correctly.

Many thanks