Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="cta-btn blue">Button</div>
<div class="cta-btn green">Button</div>
<div class="cta-btn red">Button</div>

SassMeister-input.scss

// ----
// Sass (v3.3.14)
// Compass (v1.0.1)
// ----

$colours: (
  header: #35383c,
  headerDark: #1e2226,
  blue: #0266C8,
  green: #8fc968,
  orange: #E06B1C,
  red: #bd362f
);

@mixin vendor ($property, $value...) {
    -webkit-#{$property}:$value;
    -moz-#{$property}:$value;
    -ms-#{$property}:$value;
    -o-#{$property}:$value;
    #{$property}:$value;
}

@mixin btn($name){
  $color: map-get($colours, $name);
  &.#{$name}{
    background-color: $color;
		border: none;
		color: #fff;
		
		&:hover {
		  background-color: darken($color, 10%);
		}
  }
}

.cta { 
	&-btn {
		background: none;
		border: 1px solid map-get($colours, header);
		@include vendor(border-radius, 4px);
		color: map-get($colours, header);
		display: inline-block;
		font-family: "Open Sans";
		font-weight: 600;
		height: auto;
		margin: 0 0 2px;
		overflow: hidden;
		padding: 6px 10px;
		position: relative;
		width: auto;
		
		@include btn(blue);
		@include btn(green);
		@include btn(red);
	}
}

SassMeister-output.css

.cta-btn {
  background: none;
  border: 1px solid #35383c;
  -webkit-border-radius: 4px;
  -moz-border-radius: 4px;
  -ms-border-radius: 4px;
  -o-border-radius: 4px;
  border-radius: 4px;
  color: #35383c;
  display: inline-block;
  font-family: "Open Sans";
  font-weight: 600;
  height: auto;
  margin: 0 0 2px;
  overflow: hidden;
  padding: 6px 10px;
  position: relative;
  width: auto;
}
.cta-btn.blue {
  background-color: #0266c8;
  border: none;
  color: #fff;
}
.cta-btn.blue:hover {
  background-color: #014c96;
}
.cta-btn.green {
  background-color: #8fc968;
  border: none;
  color: #fff;
}
.cta-btn.green:hover {
  background-color: #73bb43;
}
.cta-btn.red {
  background-color: #bd362f;
  border: none;
  color: #fff;
}
.cta-btn.red:hover {
  background-color: #942a25;
}

SassMeister-rendered.html

<div class="cta-btn blue">Button</div>
<div class="cta-btn green">Button</div>
<div class="cta-btn red">Button</div>