SCSS / SASS dynamic margin and padding classes in rem, using @Mixins. Can be customised as needed.

dynamic-spaces.scss

$spaces: 20;
@mixin margin($size) {
	margin: $size + rem;
}
@mixin margin-top($size) {
	margin-top: $size + rem;
}
@mixin margin-left($size) {
	margin-left: $size + rem;
}
@mixin margin-right($size) {
	margin-right: $size + rem;
}
@mixin margin-bottom($size) {
	margin-bottom: $size + rem;
}
@mixin padding($size) {
	padding: $size + rem;
}
@mixin padding-top($size) {
	padding-top: $size + rem;
}
@mixin padding-left($size) {
	padding-left: $size + rem;
}
@mixin padding-right($size) {
	padding-right: $size + rem;
}
@mixin padding-bottom($size) {
	padding-bottom: $size + rem;
}
@for $i from 1 through $spaces {
	.margin-#{$i} {
		@include margin($i);
	}
	.margin-top-#{$i} {
		@include margin-top($i);
	}
	.margin-left-#{$i} {
		@include margin-left($i);
	}
	.margin-right-#{$i} {
		@include margin-right($i);
	}
	.margin-bottom-#{$i} {
		@include margin-bottom($i);
	}
	.padding-#{$i} {
		@include padding($i);
	}
	.padding-top-#{$i} {
		@include padding-top($i);
	}
	.padding-left-#{$i} {
		@include padding-left($i);
	}
	.padding-right-#{$i} {
		@include padding-right($i);
	}
	.padding-bottom-#{$i} {
		@include padding-bottom($i);
	}
}