Mobile version is mobile friendly with and without mobile plugin

Hi,

I have installed the theme and setup for PC but when I saw for mobile it wast mobile friendly so I installed the prebuilt in theme mobile plugin but still the site seems broken on mobile.

https://www.quantifiedstrategies.com/

OK, I have figured out something..

I wanted to change the container width so I make the changes style.css file. here what I did –

.td-container {
width: 1200px;
background-color: white;

}

so as soon I make it 1200px; my site design get ruined. and even after changing the it back to its original number wasnt helping as well. so i copy and paste the code in the additional CSS and thats why the same width is showing on mobile.