</div>
{% endexample %}
-The above example creates three equal-width columns on small, medium, large, and extra large devices using our [predefined grid classes](). Those columns are centered in the page with the parent `.container`.
+The above example creates three equal-width columns on small, medium, large, and extra large devices using our [predefined grid classes](#predefined-classes). Those columns are centered in the page with the parent `.container`.
## Grid options
## Sass mixins
-When using Bootstrap's source Sass files, you have the option of using Sass variables and mixins to create custom, semantic, and responsive page layouts. Our [prebuilt grid classes](#example-stacked-to-horizontal) use these same variables and mixins to provide a whole suite of ready-to-use classes for fast responsive layouts.
+When using Bootstrap's source Sass files, you have the option of using Sass variables and mixins to create custom, semantic, and responsive page layouts. Our [predefined grid classes](#predefined-classes) use these same variables and mixins to provide a whole suite of ready-to-use classes for fast responsive layouts.
### Variables