Since the sidebar customization is the only thing I see in your Custom CSS, I’d remove whatever you have there now and paste in the following. This is just a block of code that includes the individual snippets I posted above. Hopefully that will fix it:
/* remove the existing sidebar heading text */
.s1 .sidebar-top p:first-child,
.s2 .sidebar-top p:first-child {
display: none;
}
/* new main sidebar heading */
.s1 .sidebar-top:before {
content: "New Heading Left";
}
/* new secondary sidebar heading */
.s2 .sidebar-top:before {
content: "New Heading Right";
}
/* style the new headings */
.s1 .sidebar-top:before,
.s2 .sidebar-top:before {
color: #fff;
font-size: 18px;
font-weight: 600;
padding: 2px 0;
}
/* adjust for secondary sidebar heading height */
.s2 .sidebar-top:before {
padding: 3px 0;
}
/* bring social links up into the sidebar heading */
.s1 .sidebar-top .social-links {
padding-top: 0;
margin-top: -25px;
}
/* adjust new sidebar heading color to match social icons in mobile view */
@media only screen and (max-width: 960px) and (min-width: 479px) {
.s1 .sidebar-top:before {
color: #666;
}
}
@media only screen and (max-width: 1200px) and (min-width: 479px) {
.s2 .sidebar-top:before {
color: #666;
}
}