Post and page width

Hi my website is dermprincess.com. I started using customizr theme for the first time today. I have been looking everywhere online and in this forum for help adjusting the width of the text of posts. I find my site to be way too wide on Safari. I want more white space before the start of the sidebars.

I found some code on another thread
body {
margin: 0 auto;
max-width: 800px;
}

But that makes it so that the pictures are still very wide. Does anybody know how I can edit this? I don’t remember the site being so wide in the preview. Thanks for your help!