Custom CSS for title area

Hello,

I have a page where I have added a page id to custom css to change the color and background of the title container.

.page-id-2957 .title_container { background: url(http://); }

.page-id-2957 .title_container{
background-color: #ffffff;
}

.page-id-2957 .main-title a { color: #444444!important;}
.page-id-2957 .breadcrumb-trail * { color: #444444!important; }

The above works for that page and was done a while back. However, adding a page today and using the same custom css (albeit with a different page id) has no effect? Can’t figure out why it works on one page and not the other which is virtually identical in structure:

.page-id-3841 .title_container { background: url(http://); }

.page-id-3841 .title_container{
background-color: #fffffft;
}

.page-id-3841 .main-title a { color: #444444!important;}
.page-id-3841 .breadcrumb-trail * { color: #444444!important; }

Any ideas?

Thanks

Andrew