Certain types of seperator lines from epub files from Archive of Our Own not showing up

[HannahBanana1312]

From AO3 website From Librera

I haven't been able to find a setting that helps with fixing this.

If it helps, the code of this separator when looking at the epub in Sigil is

 {
    color: gray;
    display: block;
    height: 2px;
    margin: 0.5em auto;
    border: currentColor inset 1px
    }