custom padding on images / changing header padding

Site URL: http://www.alexandrawuzyk.com/

Dear wizards of code,

would someone be able to help me with the code to add for the following changes?

- adding a custom (increased) padding to an image on my home screen

(sidenote: is it possible to add changes which apply differently to mobile version, and desktop version? e.g. I may prefer to add a different amount of padding to my image, to avoid it becoming too small)

- decreasing the automatic padding on my header (which pushes the content too far down)

In green is indicated where I desire that circular image to be

Thank you, 

PS.  I am quite new to coding, so being explicit is appreciated

(template is Forte)

Hi. Try adding to Design > Custom CSS

header#header {
    padding-bottom: 0px;
}