How CSS makes the content out of HTML appear as ellipses

The text exceeds the need to hide and display the ellipsis this is often used in the work, I think a lot of people have come across it, there are two ways to solve
The first, with the program to open the interception of character length, this is actually possible.
The second is to share the content, using CSS style to do, not much to say, directly on the code bar:
Html:

<class= "Css1">Web Front-end development – focus on website front-end design and Web user experience </Div  ><class= "Css2">Web Front-end development – Focus on website front-end design and Web user experience </div>

Css:

. Css1{Color:#6699ff;Border:1px solid #ff8000;Margin-bottom:20px;width:20em;/*semi-kanji truncation is not allowed*/}. Css2{Overflow:Hidden;/*Automatically hide text*/Text-overflow:ellipsis;/*add ellipses after text is hidden*/White-space:nowrap;/*force no Line break*/width:10em;/*semi-kanji truncation is not allowed*/Color:#6699ff;Border:1px solid Red; }

Ok! Thanks for reading!!!

How CSS makes the content out of HTML appear as ellipses