discurso is a theme by codematurgy, responsive to a smaller screen size and featuring a good chunk of options:

show or hide your header on the mobile version(not available for desktop version!)

choose if you’d rather upload your own sidebar image, use your header(which makes you load less images) or use no sidebar image at all

choose if you’d like to show your avatar on desktop(it will always show on mobile version)

pick between three margin sizes

pick between three sidebar widths

pick between three font sizes

hide or show captions on index

hide or show tags on index

hide or show search bar

pick between light or dark background posts

pick between light or dark font for links over accent colors

insert post size(maximum size is 700)

credits go to:

photosets by PixelUnion

captions and other tumblr variables by bychloethemes

customised like button by mikedidthis on Stack Overflow