Specify for posts but not pages

Hello!

I want to hide my sidebar on posts but not pages. I’ve added
.post.single > .fright {display: none; }
It’s removed the sidebar on all pages and posts.

Any idea how I can specify that this is for posts only, not pages? I’m using a Baskerville theme.

Thanks!

https://ww.wp.xz.cn/plugins/simple-custom-css/