Changing post navigation align next and previous

Hello,
i try to aline the next and previous link, on post.

i used this code

.post-navigation {
    display: flex;
}

.nav-previous {
    margin-right: auto;
}

.nav-next .next:before {
    display: none;
}

.nav-next .next:after {
    font-family: GeneratePress;
    content: "\f105";
    text-decoration: inherit;
    position: relative;
    margin-left: .6em;
    width: 13px;
    text-align: center;
    display: inline-block;
    -moz-osx-font-smoothing: grayscale;
    -webkit-font-smoothing: antialiased;
    font-style: normal;
    font-variant: normal;
    text-rendering: auto;
    line-height: 1;
    speak: none;
}

from this post here
but it leaves a missing error icon on the right.

any idea?