Wrap content around right sidebar with CSS

hello all! I’m at a bit of a loss. I’m not sure what to do next to make this work, or if it’s even possible with Hemingway. But I’m trying to get the main content to wrap around the right sidebar in my site.
here’s a page of my site: http://riversidenaturecenter.org/index/about-rnc/

my css looks like this:
.sidebar {
display: inline;
}

.widget-content {
padding: 0;
margin: 0;
width: 60%;
}

.content_left {
padding: 0;
margin: 0 0 0 5px;
width: 100%;
}

.div.wrapper.section-inner {
padding: 0;
width: 120%;
}

I would like to use only css, but I’m not sure if I need HTML or Javascript as well. Thanks!