How to change width for main container post and right sidebar responsive.

I have encountered similar cases of this article

https://colorlibsupport.com/t/how-to-change-width-for-main-container-post-container-and-right-sidebar/
I added css to my website

/*Post content*/
#primary {
width: 70%;
max-width: 100%;
}

/*Full container for both primary and secondary*/
.container {
margin: 0 auto;
max-width: 90%;
}

But on the mobile interface is not responsive.Help me

Hi there

Please provide link to your page