how to center the top Menu without messing the toggle …

Hello,
how to center the top Menu without messing the toggle menu @767pix.
I tried so much and cannot figure it out. Would you please help me. I am making theme child, I created style.css .
If I put this code:
.navbar-nav {
background-color: rgb(37, 37, 37);
float: none;
margin-left:auto;
margin-right:auto;
display: table !important; /*made the menu center/*
table-layout: fixed;
height:35px;
}
it would center the menu, but when I look at the drop down menu all the list are center as well and I want them to be on the left.
Would you please help me?
Thank you!