Question

How should I use CSS declaration?

This way:

div#main_content {
    width: 900px;
    border: 1px solid #CCC;
    margin: 20px 0 20px 0;
    padding: 40px;
    overflow: hidden;
}

or this way:

#main_content {
    width: 900px;
    border: 1px solid #CCC;
    margin: 20px 0 20px 0;
    padding: 40px;
    overflow: hidden;
}

In sublime text 2, sublime linter package suggested me to use without the div – only #main_content, but on some tutorial I saw that it is better to use div#main_content as it is easier to parse.

What do you suggest I should use? (I think result will be the same in this case for the classes)

Answer 1

Better to just use the id. There should only be one element on the page with a given id, so the element type is redundant.

Another reason to miss off the element type is that if you decide to change your HTML (maybe changing the <div> to something more semantic like a <p> or <section>) the CSS selector will still match.