How can I use Javascript to implement the changes in CSS

I am new in using Javascript and I want to use Javascript to implement the CSS code below. I need to use javascript since the client want to have this for a specific logic only.

.Skin label.MultipleAnswer, .Skin label#QID2-0-label.SingleAnswer{
background: #E43E3D;
}
.Skin label.MultipleAnswer, .Skin label#QID2-1-label.SingleAnswer{
background: #EA484D;
}
.Skin label.MultipleAnswer, .Skin label#QID2-2-label.SingleAnswer{
background: #EC654E;
}
.Skin label.MultipleAnswer, .Skin label#QID2-3-label.SingleAnswer{
background: #EF874C;
}
.Skin label.MultipleAnswer, .Skin label#QID2-4-label.SingleAnswer{
background: #F3A74C;
}
.Skin label.MultipleAnswer, .Skin label#QID2-5-label.SingleAnswer{
background: #F8C43D;
}
.Skin label.MultipleAnswer, .Skin label#QID2-6-label.SingleAnswer{
background: #E1C63B;
}
.Skin label.MultipleAnswer, .Skin label#QID2-7-label.SingleAnswer{
background: #C1CC36;
}
.Skin label.MultipleAnswer, .Skin label#QID2-8-label.SingleAnswer{
background: #9FCD35;
}
.Skin label.MultipleAnswer, .Skin label#QID2-9-label.SingleAnswer{
background: #7FCD31;
}
.Skin label.MultipleAnswer, .Skin label#QID2-10-label.SingleAnswer{
background: #5AAF2B;
}