Split Screen - Mobile view not working

Hello, 
I recently noticed a few things have changed in my split screen sections even though I haven't changed the code.

1. The text (content-wrapper) on the left would move under the photo in mobile view, it now sits on top.
2. The background colour of the section isn't appearing either.

I hope someone can help me, as It was previously working perfectly.

Thank you!!

[data-section-id="60bda31d40956e03d4135f0f"]{
background-color:#F4F4F4; 
@media(min-width:767px){
 .section-background{
width:50%;
margin-left:50%; 
}
.content-wrapper {
width:50%;
margin-right:50% !important;
}
}
@media(max-width:767px){
display:block;
.section-background, .content-wrapper{
position:relative;
}
.section-background{
height:300px;
}
}

Change class name

.section-background

to

.section-border