Hello Guy's and Girl's i have problems with my website i have a header the size is 900px X 100px and my nav is 900px X 35px but my nav doesnt go to the end of my header i have no idea what i am doing wrong can you please take a look i think its my css code so i will so you my css code

main.css

wrapper{

width: 900px;
margin-left: auto;
margin-right: auto;

}

wrapper #header {

  height: 100px;

}

wrapper #nav {

background-image: url(../images/nav.png);
background-repeat: no-repeat;
height: 35px;

}

wrapper #content{

width: 850px;
margin-left: auto;
margin-right: auto;
min-height: 400px;

}

wrapper #footer {

background-image: url(../images/nav.png);
background-repeat: no-repeat;
height: 35px;

}