Thnx...
It didn't work completely as it should but after some comparison with other CSS files i found the problem.
The problem was that the text area shrunk and the cursor went missing (hiding behind the color).
I changed your version in an extra line and now it is:
#txt {
background-color: #555;
width: 100%;
height: 60px
}
Grey as the color also works but this number fits better.