#nav-wrapper {
display: block;
}
#navbar {
position: absolute !important;
top: 30px;
left: 50%;
transform: translateX(-50%);
}<body class="main-page-body">
...
</body><body class="inner-page-body">
...
</body>.main-page-body {
background-color: red;
}
.inner-page-body {
background-color: blue;
}