Why sometimes the css page does not work properly, like this case?


As you can see in the image and in this fiddle http://jsfiddle.net/W5Yu4/ I have written the css style and the class in the HTML part but it does not work correctly, like it is not recognize the css class.

.model-landing-page .explore-wrapper {
width: 930px;
margin-bottom: 20px;
float: left;
border: solid 5px #96172e;
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;
padding-bottom: 10px;

What am I doing wrong here?

Your styles are looking for an element with class .explore-wrapper wrapped in an element with class .model-landing-page. I do not see .model-landing-page in your HTML, try adding this class to your body.