Try using
*{
margin:0;
}
and/or
.nav1 ul {
display: inline;
}
The first code will remove the default browser margin from the webpage, and the second code will display .nav1 ul
as an inline element
Also, it's a good idea to think about removing .nav1{float:left;}
since it doesn't affect anything, and change the .links_container
width to 100% instead of 1000px.