You could use the sass `@extend` here.

```scss
.social-base {
  -o-transition:.3s;
  -ms-transition:.3s;
  -moz-transition:.3s;
  -webkit-transition:.3s;
  transition:.3s;
  -webkit-box-shadow: 1px -10px 84px 0px rgba(255,255,255,0.75);
  -moz-box-shadow: 1px -10px 84px 0px rgba(255,255,255,0.75);
  box-shadow: 1px -10px 84px 0px rgba(255,255,255,0.75);
}
.github-social:hover {
  @extend social-base;
  color: #000;
}
.twitter-social:hover {
  @extend social-base;
  color: #00aced;
}
.linkedin-social:hover {
  @extend social-base;
  color: #007bb6;
}
```