horizontal line and right way to code it in html, css

Question

I need to draw a horizontal line after some block, and I have three ways to do it:

1) Define a class h_line and add css features to it, like

#css
.hline { width:100%; height:1px; background: #fff }

#html
<div class="block_1">Lorem</div> <div class="h_line"></div>

2) Use hr tag

#css
hr { width:100%; height:1px; background: #fff }

#html
<div class="block_1">Lorem</div> <hr />

3) use it like a after pseudoclass

#css
.hline:after { width:100%; height:1px; background: #fff; content:"" }

#html
<div class="block_1 h_line">Lorem</div>

Which way is the most practical?

Answer 1

hr {
    display: block;
    height: 1px;
    border: 0;
    border-top: 1px solid #ccc;
    margin: 1em 0;
    padding: 0;
}

<div>Hello</div>
<hr/>
<div>World</div>

Here is how html5boilerplate does it:

hr {
    display: block;
    height: 1px;
    border: 0;
    border-top: 1px solid #ccc;
    margin: 1em 0;
    padding: 0;
}