#header #welcome { float: left; font-family: "Ubuntu Condensed"; font-size: 25px; padding-top: 10px; position: relative; width: 40%; }замените на:
#header #welcome { float: left; font-family: "Ubuntu Condensed"; font-size: 25px; padding-top: 10px; position: relative; text-align: center; width: 40%; }