CSS as tag.

Read : How to define CSS in General HTML & in Blogger.

Removing a dot while defining CSS will help you to use CSS style as tag.
For example :
We defined CSS with a prefixed dot as,

.textborder{border:0.5px solid black}

and used as,

<div class="textborder">Something here</div>

Now, we will define the CSS in the same way, but without a dot as

textborder{border:0.5px solid black}

and use as,

<textborder>Something here</textborder>

The result will be as follows :-
Something here and when your text expands, the border will expand
And, when you come to next line, It will look like this. Border for each line.