Div is not filling up the page

I’ve created two small blocks but i does not start from the screen edges but it takes space from left and right and top too. here is my code

HTML

<body>
  <div id="header"></div>
  <div id="block1"></div>
</body>

CSS

#header {
  background:#1A2328;
  height:150px;
}

#block1 {
  height:600px;
  background:#657;
}

jsFiddle here


solution

You have to reset the default user agent stylesheet.

Here is a basic example.

body {
  margin:0px;
  padding:0px;
}

jsFiddle demo

I suggest looking at a CSS reset , see Eric Meyer’s here.