Add this.
#page {
position: relative;
}
Then change out #text-3 with this.
#text-3 {
height: 48px;
left: 80px;
margin: 0;
position: absolute;
top: 45px;
width: 300px;
z-index: 1000;
}
The above is not perfect as the text starts to move to the left out from under the widget when the browser window is narrowed to the point that the theme starts to narrow, but at the moment that is the best we can do.
The other way to do this would be to replace your image in the text widget (linked to your main page) with the logo image URL and then remove this from your CSS.
#site-title {
background: url("http://fabricaliteraria.files.wordpress.com/2011/10/logo_fl_1_.jpg") no-repeat scroll left bottom transparent;
}
We would then be relying on the text widget alone and the movement would not be an issue.