Why I can't set the width of the template?

I just installed zencart 1.3, and I tried to set the width to 100%, but it seems to me that no matter how I change to value of the width in stylesheet.css, it simply stays - I guess - 750px.

#mainWrapper {
background-color: #ffffff;
text-align: left;
width: 100%;
vertical-align: top;
}

Is there another file that needs to be changed?
Can somebody help me out?

What's your URL?
What template are you working from?

test100:

I just installed zencart 1.3, and I tried to set the width to 100%, but it seems to me that no matter how I change to value of the width in stylesheet.css, it simply stays - I guess - 750px.

#mainWrapper {
background-color: #ffffff;
text-align: left;
width: 100%;
vertical-align: top;
}

Is there another file that needs to be changed?
Can somebody help me out?As you have just installed v1.3 you have probably defaulted to the Classic Template. This has two stylesheets _new and _original and the page width is set in both. Your mainWrapper (which you will be setting to 100% in _new is expanding. But just inside it is a table (centershop) also width 750px set in _original.

This is just a taster of the problems that you will have using the Classic Template. This template is intended primarily for backward compatibility with earlier versions of Zen Cart and has been hacked about somewhat to achieve this making for a rather more complex stylesheet than a new site needs and more tables-based layout than is the case for a completely clean installation based on the template_default.

It would be better to build your own template from scratch based on the functionality in the template_default (which has width 100%). A little more work up front, but much, much easier in the long-term.

If that seems a bit overwhelming, an alternative is to start from the Future Zen template which engages template_default for you and amend that. You can download it from the downloads section of this site and there's a link to the relevant downloads page in my signature below.

Thank you very much, Kuroi.

After making a change in stylesheet_original.css (in includes/templates/classic/css)

.centershop {
padding: 0px;
margin: 0px auto;
/position: relative;/
text-align: left;
width: 100% !important;

now it's set to 100%.

I'll also try future zen template.

I appreciate your help.

Well behaved templates (and future Zen is very well behaved) should not interfer with each other, so you should be able to try several and just switch between then in the Admin until you find a jumping off point you like. I recommend finding one built on the template_default (will have a single stylesheet) with minimal use of tables.