Sempre que eu mudo a tag do float, não fica centralizado na forma horizontal, apenas vertical.
Sou iniciante ainda, sorry kkk
<div class="topnav">
<!--<a href="#"><img src="nr-logo.jpg" width="50"></a>-->
<a href="#">Inicio</a>
<a href="#">MENU 1</a>
<a href="#">MENU 2</a>
<a href="#">MENU 3</a>
<a href="#">MENU 4's</a>
<a href="#">MENU 5</a>
<a href="#">MENU 6</a>
</div>
.topnav {
overflow: hidden;
background-color: #fff;
border-style: outset;
border-width: 0.1px;
text-align: justify;
}
.topnav a {
float: left;
display: block;
color: #000;
padding: 15px 30px;
text-decoration: none;
font-weight: normal;
text-align: justify;
}
.topnav a:hover {
background: -webkit-linear-gradient(#21d4fd, #b721ff, #21d4fd, #b721ff);
background: -o-linear-gradient(right, #21d4fd, #b721ff, #21d4fd, #b721ff);
background: -moz-linear-gradient(right, #21d4fd, #b721ff, #21d4fd, #b721ff);
background: linear-gradient(right, #21d4fd, #b721ff, #21d4fd, #b721ff);
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;
color: black;
}