body {
margin: 0;  
}
.topnav {
overflow: hidden;
background-color: #ff0033;
}
.topnav a {
float: left;
display: block;
color: #fff;
text-align: center;
padding: 14px 13px;
text-decoration: none;
font-size: 15px;
font-family: Arial, Helvetica, sans-serif;
}
.topnav a:hover {
background-color: #fff;
color: #000;
}
.active {
background-color: #4CAF50;
color: #fff;
}
.topnav .icon {
display: none;
}

@media screen and (max-width: 600px) {
.topnav a:not(:first-child) {display: none;}
.topnav a.icon {
float: right;
display: block;
}
}

@media screen and (max-width: 600px) {
.topnav.responsive {position: relative;}
.topnav.responsive .icon {
position: absolute;
right: 0;
top: 0;
}
.topnav.responsive a {
float: none;
display: block;
text-align: left;
}
}