Utility mixins for custom elements and responsive helpers

=arrow($color) Creates a CSS-only down arrow. Used for the dropdown select.
=block Defines a margin-bottom of 1.5rem, except when the element is the last child. Used for almost all block elements.
=clearfix Adds a clearfix at the end of the element. Used for the "is-clearfix" helper.
=center($size) Positions an element in the exact center of its parent. Used for the spinner in a loading button.
=delete Creates a CSS-only cross. Used for the delete element in modals, messages, tags...
=fa($size, $dimensions) Sets the style of a Font Awesome icon container.
=hamburger($dimensions) Creates a CSS-only hamburger menu with 3 bars. Used for the "nav-toggle".
=loader Creates a CSS-only loading spinner. Used for the ".loader" element, and for input and button spinners.
=overflow-touch Sets the style of a container so that it keeps momentum when scrolling on iOS devices.
=overlay($offset: 0) Makes the element overlay its parent container, like the transparent modal background.
=placeholder Sets the styles of an input placeholder.
=unselectable Turns the element unselectable. Used for buttons to prevent selection when clicking.

These mixins are already used throughout Bulma, but you can use them as well to extend your own styles.