重要なのは、ブロック要素にposition: relativeを指定し、要素内にposition: absoluteを指定することです。
http://jsfiddle.net/coma/FeVsr/12/
HTML
<div class="news">
<a href="#" class="boxing" style="background-image:url(https://si0.twimg.com/profile_images/3162594037/e232a8ce35fe8ce856e4a52a16141f20.jpeg);">
<div class="summary">...</div>
<div class="content">...</div>
</a>
<a href="#" style="background-image:url(https://si0.twimg.com/profile_images/3162594037/e232a8ce35fe8ce856e4a52a16141f20.jpeg);">
<div class="summary">...</div>
<div class="content">...</div>
</a>
</div>
CSS
body {
font-family: Arial, Helvetica, sans-serif;
}
div.news {
padding: 10px;
background: #eee;
}
div.news:after {
content: "";
display: block;
clear: both;
}
div.news > a {
display: block;
float: left;
width: 200px;
border: 5px solid #fff;
margin: 0 8px 8px 0;
box-shadow: 0 0 3px rgba(0, 0, 0, .5);
position: relative;
background: #009BFF none no-repeat top;
background-size: cover;
font-size: 12px;
text-decoration: none;
color: #fff;
}
div.news > a > div.summary {
position: absolute;
bottom: 0;
left: 0;
right: 0;
height: 50px;
padding: 5px;
overflow: hidden;
background-color: rgba(0, 0, 0, .7);
line-height: 1.4em;
}
div.news > a > div.content {
min-height: 200px;
position: relative;
opacity: 0;
background-color: inherit;
transition: opacity .5s;
padding: 25px 5px 5px 5px;
z-index: 1;
font-size: 13px;
line-height: 1.4em;
}
div.news > a:hover > div.content {
opacity: 1;
}
div.news > a:before {
content: "news";
display: block;
padding: 3px;
background-color: inherit;
position: absolute;
top: 0;
left: 0;
text-transform: uppercase;
z-index: 2;
}
div.news > a.people {
background-color: #9600B4;
}
div.news > a.boxing {
background-color: #EB1E00;
}
div.news > a.business {
background-color: #00A53C;
}
div.news > a.people:before {
content: "people";
}
div.news > a.boxing:before {
content: "boxing";
}
div.news > a.business:before {
content: "business";
}