Container Width For Whole Site & Individual Sections Of Pages

Hi All,

I’ve noticed that a lot of WordPress websites’ content extends further to the edges of the screen than my own website – and I understand this is something to do with the container width settings?

Are there css settings that allow for:
a) a wider / variable container width setting across the whole site, and
b) a wider / variable container width for a specific section with a specific page (e.g. a Color Section or a Column Layout)?

So far I’ve been able to adjust the container width setting of an entire page using:
.page-id-XXXX .container {
padding: 0px 20px;
}
And also the width of the Header section using:
#header #header_main .container {
width: 90%;
max-width: none;

However, my preference would be to either adjust the whole site or specific page sections.

Many thanks in advance.

Ray