Hi there,
you’re missing the CSS styling for the custom post nav which is here, the very last rule is what you can change the Next / Previous colors with:
/* CUSTOM POST NAVIGATION - ENSURE GP NAV IS DISABLED */
#post-nav a,
#post-nav .post-nav-wrap {
-webkit-box-sizing: border-box;
box-sizing: border-box;
}
#post-nav,
#post-nav .post-nav-wrap {
display: -webkit-box;
display: -ms-flexbox;
display: flex;
}
#post-nav a {
-webkit-box-flex: 1;
-ms-flex: 1 0 50%;
flex: 1 0 50%;
box-sizing: border-box;
}
@media (max-width: 768px) {
#post-nav a {
-webkit-box-flex: 1;
-ms-flex: 1 0 100%;
flex: 1 0 100%;
}
}
#post-nav .post-nav-wrap {
background-size: cover !important;
background-position: center center !important;
min-height: 120px;
height: 100%;
padding: calc(6% + 1em) 5%;
-webkit-box-shadow: inset 0 -50px 70px 20px rgba(0, 0, 0, 0.5);
box-shadow: inset 0 -50px 70px 20px rgba(0, 0, 0, 0.5);
-webkit-transition: -webkit-box-shadow 500ms;
transition: -webkit-box-shadow 500ms;
transition: box-shadow 500ms;
transition: box-shadow 500ms, -webkit-box-shadow 500ms;
position: relative;
}
#post-nav .post-nav-wrap:hover {
-webkit-box-shadow: inset 0 -90px 70px 20px rgba(0, 0, 0, 0.5);
box-shadow: inset 0 -90px 70px 20px rgba(0, 0, 0, 0.5);
}
.post-nav-wrap>* {
color: #fff;
}
.post-nav-date {
font-size: 0.9em;
}
.post-nav-title {
margin: 5px 0 !important;
}
.post-nav {
min-width: 60px;
position: absolute;
top: 0;
border-radius: 0 0 2px 0;
}
.post-nav:first-child {
left: 0;
}
.post-nav:last-child {
right: 0;
}
.post-nav {
background-color: #ff3366;
color: #fff !important;
padding: 5px;
}