Changing color of previous post next post bar

Okay, I am using this code to try and change the color of the previous and next bars:

.site-main .post-navigation .nav-next a, .site-main .paging-navigation .nav-next a {
background: #25035a;
color: rgba(255, 255, 255, 0.5);
float: right;
padding: 15px 65px 15px 15px;
position: relative;
text-align: center;
width: 50%;
}

This has worked for the “next post” portion of the bar, but not for the “previous” post. If I am able to change the default color for Pictorico, will this fix it? In other words, is the “previous post” portion of the bar linked to the default color? How would I target that?
Thank you.