@cfarquharson What he is asking for is to create a placeholder for the button block as follows:
```scss
%grids-icon-button-padding-left-10-padding-right-10 {
	&.button {
		padding-left: 10px;
		padding-right: 10px;
	}
}
```
Next he is asking that you replace the two button blocks (lines 98 - 101 and 108 - 111) with the following:
```scss
	@extend %grids-icon-button-padding-left-10-padding-right-10;
```
That way SASS can combine them to reduce the resulting CSS size.