Indentation of the first line in CSS

Everyone is familiar with the indentation of the first line in CSS. It is nothing more than adding the following content on this page:

<Style>

P {

Font-size: 14px;

Text-indent: 2em;

}

</Style>

Or write it in the externally called CSS:

P {

Font-size: 14px;

Text-indent: 2em;

}

If none of the above works, add the following content to each section:

<P sytle = "text-indent: 2em"> body </P>

When these cannot be indented, text-indent does not work. How is this good? Now many browsers support this CSS function, but why is there no effect? This is a bit uncomfortable. It is because the path of the CSS external call is incorrect. In this case, it should be normal to put the first method in a single page, but there is still no response (ie, FF didn't respond). If the third type is used, it will be troublesome and will not add this to every normal text. It seems that, text-indent does not work.

I don't know why the senior man said so?