I don\'t understand this:
I have tried to center the text-align of a HTML tag but it did nothing...
With the
Spans are inline, divs are block elements. i.e. spans are only as wide as their respective content. You can align the span inside the surrounding container (if it's a block container), but you can't align the content.
Span is primarily used for formatting purposes. If you want to arrange or position the contents, use div, p or some other block element.