[Theme: Autofocus ] Can't change original size of images

Hello,

i have the following problem: For the Autofocus template, the images that i post to articles, keep their original size. I tried set the size that i want both from css and from article creation. But i didn’t manage to achieve anything. From article creation, for example i set images to have 300×300 size. Althougth it seems to be ok, when i post the article, the images still have their original size.
I know i can set the size of the image before i upload it, but it would be nice if i could scale the image proportionally, in order to be nice viewed from a mobile phone etc.

Does anyone have an idea of what is happening?

Here is an article of my blog to check it:
http://topaiditissolinas.heliohost.org/wp/%CE%BB%CE%AF%CE%BC%CE%BD%CE%B7-%CE%BA%CF%8C%CE%BC%CE%BF/