Responsive Images

I need to make all images of my site responsive,
exist any shortcode or CSS to make images responsive?=
where i must to put in?

the site: www.ceciliavega.cl

thanks!

 

Hello,

Paste this code in Custom CSS
Appearance > Theme Option > Styling Option > Custom CSS

Code:

 div.fullwidth img {
max-width: 100%;
}

Thanks & Regards
Gourav Shrivastava

 

thankyou very much.