How to make my blog posts skinny?

[dfmarketing]

Right now my blog posts look extremely wide and it looks ugly.
Check it out: https://www.techknowledgeyinc.com/it-vendor-management-services/
How can I fix the margins so it looks normal and easier to read?
I want it too look something like this: http://www.bluestarpro.com/5-cybersecurity-tips-for-employees/

Can someone please help me?

[Prasant]

Hello @dfmarketing,

Thanks for writing in!

Please add following CSS under X > Theme Options > CSS:

.entry-featured {
    width: 100%;
    margin-top: 40px;
}

.single-post .x-container {
    width: 70%;
}

1- I have found the proper CSS code selector using the Chrome browser Developer Toolbar: https://www.youtube.com/watch?v=wcFnnxfA70g

2- For the CSS code itself, I suggest that you get started with this tutorial: https://www.youtube.com/watch?v=yfoY53QXEnI

Thanks.