Sidebar Width Expansion within WordPress

I am currently building out a custom landing page template using Divi from Elegant Themes. One item I want to do is expand the width of the sidebar that is showing up on the page.

Currently it's appearing at roughly 200px in width and I would like to expand it to closer to around the 300px amount.

I have gone ahead and added in this snippet of code to the style.css file within my child theme, but it doesn't seem to be triggering any difference in width for the sidebar.

.sidebar {
     width: 300px !important;
}

.content-sidebar #content,
.sidebar-content #content {
     width: 780px !important;
}

Perhaps I've just labeled the sidebar wrong within the CSS?

Any thoughts?