Google Page Speed Check Error

I am getting error when I check my website for Google page speed ,below is the error ,it’s something about viewport ,I tried various methods but it’s not working like adding media queries to my custom.css

The page content is too wide for the viewport, forcing the user to scroll horizontally. Size the page content to the viewport to provide a better user experience.
The page content is 610 CSS pixels wide, but the viewport is only 320 CSS pixels wide. The following elements fall outside the viewport:
The element <div class=”tp-fullwidth-forcer”> falls outside the viewport.
The element <div class=”custom-bg p01″> falls outside the viewport.
The element <div class=”full-width-bg”>Enterprise We…rking with us.</div> falls outside the viewport.
The element <div class=”full-width-bg…shadow-enabled”>Why customers…23PreviousNext</div> falls outside the viewport.
The element <div class=”custom-bg p02″> falls outside the viewport.
The element <div class=”full-width-bg…-bottom-margin”>Our Clientspreviousnext</div> falls outside the viewport.

I added

I added the below CSS in my custom.css targeting the class but it’s not working out

@media all screen and (max-width: 320px) {
.tp-fullwidth-forcer {
width: 300px;
margin: 0 auto;
}
}