The problem is how 100% height is being calculated. Two ways to deal with this.
Add 20px to the body padding-bottom
body {
padding-bottom: 20px;
}
or add a transparent border to body
body {
border: 1px solid transparent;
}
Both worked for me in firebug
In defense of this answer
Below are some comments regarding the correctness of my answer to this question. These kinds of discussions are exactly why stackoverflow is so great. Many different people have different opinions on how best to solve the problem. I've learned some incredible coding style that I would not have thought of myself. And I've been told that readers have learned something from my style from time to time. Social coding has really encouraged me to be a better programmer.
Social coding can, at times, be disturbing. I hate it when I spend 30 minutes flushing out an answer with a jsfiddle and detailed explanation only to submit and find 10 other answers all saying the same thing in less detail. And the author accepts someone else's answer. How frustrating! I think that this has happend to my fellow contributors–in particular thirtydot.
Thirtydot's answer is completely legit. The p around the script is the culprit in this problem. Remove it and the space goes away. It also is a good answer to this question.
But why? Shouldn't the p tag's height, padding and margin be calculated into the height of the body?
And it is! If you remove the padding-bottom style that I've suggested and then set the body's background to black, you will see that the body's height includes this extra p space accurately (you see the strip at the bottom turn to black). But the gradient fails to include it when finding where to start. This is the real problem.
The two solutions that I've offered are ways to tell the browser to calculate the gradient properly. In fact, the padding-bottom could just be 1px. The value isn't important, but the setting is. It makes the browser take a look at where the body ends. Setting the border will have the same effect.
In my opinion, a padding setting of 20px looks the best for this page and that is why I answered it this way. It is addressing the problem of where the gradient starts.
Now, if I were building this page. I would have avoided wrapping the script in a p tag. But I must assume that author of the page either can't change it or has a good reason for putting it in there. I don't know what that script does. Will it write something that needs a p tag? Again, I would avoid this practice and it is fine to question its presence, but also I accept that there are cases where it must be there.
My hope in writing this "defense" is that the people who marked down this answer might consider that decision. My answer is thought out, purposeful, and relevant. The author thought so. However, in this social environment, I respect that you disagree and have a right to degrade my answer. I just hope that your choice is motivated by disagreement with my answer and not that author chose mine over yours.
