Opera

If Opera is to display the page the way the developer meant it to be displayed, you'll need to have the following setup of Tools > Preferences > Advanced > Content, under "Style Options > Presentation Modes":

Author mode                User mode
[v] Page style sheet       [ ] Page style sheet
[v] Page fonts and colors  [ ] Page fonts and colors
[ ] My style sheet         [v] My style sheet
[ ] My fonts and colors    [v] My fonts and colors
[v] My link style          [v] My link style

Also make sure "Author mode" is selected as the default mode.