CSS that I have added is affecting my dashboard…

Added this;

@media (max-width: 1920px) {
.site #content{
border-right:30px solid #ffffff;
border-left:30px solid #ffffff;
}
}

@media (max-width: 1920px) {
.site #footer{
border-right:30px solid #ffffff;
border-left:30px solid #ffffff;
}
}

@media (max-width: 600px) {
.site #content{
border-right:5px solid #ffffff;
border-left:5px solid #ffffff;
}
}

@media (max-width: 600px) {
.site #footer{
border-right:5px solid #ffffff;
border-left:5px solid #ffffff;
}
}

to add a white border on my site, however it is making my dashboard mess up. Can anyone help? Can’t even access theme options