// Helper function for the normalize() mixin.
@function _normalize-include($section, $exclude: null) {
	// Initialize the global variables needed by this function.
	@if not global_variable_exists(_normalize-include) {
		$_normalize-include: () !global;
		$_normalize-exclude: () !global;
	}
	// Since we are given 2 parameters, set the global variables.
	@if $exclude != null {
		$include: $section;
		// Sass doesn't have static variables, so the work-around is to stuff these
		// values into global variables so we can access them in future calls.
		$_normalize-include: if(type-of($include) == 'list', $include, ($include)) !global;
		$_normalize-exclude: if(type-of($exclude) == 'list', $exclude, ($exclude)) !global;
		@return true;
	}

	// Check if $section is in the $include list.
	@if index($_normalize-include, $section) {
		@return true;
	}
	// If $include is set to (all), make sure $section is not in $exclude.
	@else if not index($_normalize-exclude, $section) and index($_normalize-include, all) {
		@return true;
	}
	@return false;
}

@mixin normalize($include: (all), $exclude: ()) {
	// Initialize the helper function by passing it this mixin's parameters.
	$init: _normalize-include($include, $exclude);

	// If we've customized any font variables, we'll need extra properties.
	@if $base-line-height != 24px
		or $base-unit != 'em'
		or $h2-font-size != 1.5  * $base-font-size
		or $h3-font-size != 1.17 * $base-font-size
		or $h4-font-size != 1    * $base-font-size
		or $h5-font-size != 0.83 * $base-font-size
		or $h6-font-size != 0.67 * $base-font-size {
		$normalize-vertical-rhythm: true !global;
	}



	@if _normalize-include(document) {
		/* Document
			 ========================================================================== */

		/**
		 * 1. Correct the line height in all browsers.
		 * 2. Prevent adjustments of font size after orientation changes in
		 *    IE on Windows Phone and in iOS.
		 */

		html {
			@if $base-font-family {
				/* Change the default font family in all browsers (opinionated). */
				font-family: $base-font-family;
			}
			@if $base-font-size != 16px or $normalize-vertical-rhythm {
				// Correct old browser bug that prevented accessible resizing of text
				// when root font-size is set with px or em.
				font-size: ($base-font-size / 16px) * 100%;
			}
			@if $normalize-vertical-rhythm {
				line-height: ($base-line-height / $base-font-size) * 1em; /* 1 */
			}
			@else {
				line-height: 1.15; /* 1 */
			}
			-ms-text-size-adjust: 100%; /* 2 */
			-webkit-text-size-adjust: 100%; /* 2 */
		}
	}

	@if _normalize-include(sections) {
		/* Sections
			 ========================================================================== */

		/**
		 * Remove the margin in all browsers (opinionated).
		 */

		body {
			margin: 0;
		}

		/**
		 * Add the correct display in IE 9-.
		 */

		article,
		aside,
		footer,
		header,
		nav,
		section {
			display: block;
		}

		/**
		 * Correct the font size and margin on `h1` elements within `section` and
		 * `article` contexts in Chrome, Firefox, and Safari.
		 */

		h1 {
			@include normalize-font-size($h1-font-size);
			@if $normalize-vertical-rhythm {
				@include normalize-line-height($h1-font-size);
			}

			@if $normalize-vertical-rhythm {
				/* Set 1 unit of vertical rhythm on the top and bottom margins. */
				@include normalize-margin(1 0, $h1-font-size);
			}
			@else {
				margin: 0.67em 0;
			}
		}

		@if $normalize-vertical-rhythm {
			h2 {
				@include normalize-font-size($h2-font-size);
				@include normalize-line-height($h2-font-size);
				@include normalize-margin(1 0, $h2-font-size);
			}

			h3 {
				@include normalize-font-size($h3-font-size);
				@include normalize-line-height($h3-font-size);
				@include normalize-margin(1 0, $h3-font-size);
			}

			h4 {
				@include normalize-font-size($h4-font-size);
				@include normalize-line-height($h4-font-size);
				@include normalize-margin(1 0, $h4-font-size);
			}

			h5 {
				@include normalize-font-size($h5-font-size);
				@include normalize-line-height($h5-font-size);
				@include normalize-margin(1 0, $h5-font-size);
			}

			h6 {
				@include normalize-font-size($h6-font-size);
				@include normalize-line-height($h6-font-size);
				@include normalize-margin(1 0, $h6-font-size);
			}
		}
	}

	@if _normalize-include(grouping) {
		/* Grouping content
			 ========================================================================== */

		@if $normalize-vertical-rhythm {
			/**
			 * Set 1 unit of vertical rhythm on the top and bottom margin.
			 */

			blockquote {
				@include normalize-margin(1 $indent-amount);
			}

			dl,
			ol,
			ul {
				@include normalize-margin(1 0);
			}

			/**
			 * Turn off margins on nested lists.
			 */

			ol,
			ul {
				ol,
				ul {
					margin: 0;
				}
			}

			dd {
				margin: 0 0 0 $indent-amount;
			}

			ol,
			ul {
				padding: 0 0 0 $indent-amount;
			}
		}

		/**
		 * Add the correct display in IE 9-.
		 */

		figcaption,
		figure {
			display: block;
		}

		/**
		 * Add the correct margin in IE 8.
		 */

		figure {
			@if $normalize-vertical-rhythm {
				@include normalize-margin(1 $indent-amount);
			}
			@else {
				margin: 1em $indent-amount;
			}
		}

		/**
		 * 1. Add the correct box sizing in Firefox.
		 * 2. Show the overflow in Edge and IE.
		 */

		hr {
			box-sizing: content-box; /* 1 */
			height: 0; /* 1 */
			overflow: visible; /* 2 */
		}

		/**
		 * Add the correct display in IE.
		 */

		main {
			display: block;
		}

		@if $normalize-vertical-rhythm {
			/**
			 * Set 1 unit of vertical rhythm on the top and bottom margin.
			 */

			p,
			pre {
				@include normalize-margin(1 0);
			}
		}

		/**
		 * 1. Correct the inheritance and scaling of font size in all browsers.
		 * 2. Correct the odd `em` font sizing in all browsers.
		 */

		pre {
			font-family: monospace, monospace; /* 1 */
			font-size: 1em; /* 2 */
		}
	}

	@if _normalize-include(links) {
		/* Links
			 ========================================================================== */

		/**
		 * 1. Remove the gray background on active links in IE 10.
		 * 2. Remove gaps in links underline in iOS 8+ and Safari 8+.
		 */

		a {
			background-color: transparent; /* 1 */
			-webkit-text-decoration-skip: objects; /* 2 */
		}
	}

	@if _normalize-include(text) {
		/* Text-level semantics
			 ========================================================================== */

		/**
		 * 1. Remove the bottom border in Chrome 57- and Firefox 39-.
		 * 2. Add the correct text decoration in Chrome, Edge, IE, Opera, and Safari.
		 */

		abbr[title] {
			border-bottom: none; /* 1 */
			text-decoration: underline; /* 2 */
			text-decoration: underline dotted; /* 2 */
		}

		/**
		 * Prevent the duplicate application of `bolder` by the next rule in Safari 6.
		 */

		b,
		strong {
			font-weight: inherit;
		}

		/**
		 * Add the correct font weight in Chrome, Edge, and Safari.
		 */

		b,
		strong {
			font-weight: bolder;
		}

		/**
		 * 1. Correct the inheritance and scaling of font size in all browsers.
		 * 2. Correct the odd `em` font sizing in all browsers.
		 */

		code,
		kbd,
		samp {
			font-family: monospace, monospace; /* 1 */
			font-size: 1em; /* 2 */
		}

		/**
		 * Add the correct font style in Android 4.3-.
		 */

		dfn {
			font-style: italic;
		}

		/**
		 * Add the correct background and color in IE 9-.
		 */

		mark {
			background-color: #ff0;
			color: #000;
		}

		/**
		 * Add the correct font size in all browsers.
		 */

		small {
			font-size: 80%;
		}

		/**
		 * Prevent `sub` and `sup` elements from affecting the line height in
		 * all browsers.
		 */

		sub,
		sup {
			font-size: 75%;
			line-height: 0;
			position: relative;
			vertical-align: baseline;
		}

		sub {
			bottom: -0.25em;
		}

		sup {
			top: -0.5em;
		}
	}

	@if _normalize-include(embedded) {
		/* Embedded content
			 ========================================================================== */

		/**
		 * Add the correct display in IE 9-.
		 */

		audio,
		video {
			display: inline-block;
		}

		/**
		 * Add the correct display in iOS 4-7.
		 */

		audio:not([controls]) {
			display: none;
			height: 0;
		}

		/**
		 * Remove the border on images inside links in IE 10-.
		 */

		img {
			border-style: none;
		}

		/**
		 * Hide the overflow in IE.
		 */

		svg:not(:root) {
			overflow: hidden;
		}
	}

	@if _normalize-include(forms) {
		/* Forms
			 ========================================================================== */

		/**
		 * 1. Change the font styles in all browsers (opinionated).
		 * 2. Remove the margin in Firefox and Safari.
		 */

		button,
		input,
		optgroup,
		select,
		textarea {
			font-family: if($base-font-family, $base-font-family, sans-serif); /* 1 */
			font-size: 100%; /* 1 */
			@if $normalize-vertical-rhythm {
				line-height: ($base-line-height / $base-font-size) * 1em; /* 1 */
			}
			@else {
				line-height: 1.15; /* 1 */
			}
			margin: 0; /* 2 */
		}

		/**
		 * Show the overflow in IE.
		 */

		button {
			overflow: visible;
		}

		/**
		 * Remove the inheritance of text transform in Edge, Firefox, and IE.
		 * 1. Remove the inheritance of text transform in Firefox.
		 */

		button,
		select { /* 1 */
			text-transform: none;
		}

		/**
		 * 1. Prevent a WebKit bug where (2) destroys native `audio` and `video`
		 *    controls in Android 4.
		 * 2. Correct the inability to style clickable types in iOS and Safari.
		 */

		button,
		html [type="button"], /* 1 */
		[type="reset"],
		[type="submit"] {
			-webkit-appearance: button; /* 2 */
		}

		button,
		[type="button"],
		[type="reset"],
		[type="submit"] {

			/**
			 * Remove the inner border and padding in Firefox.
			 */

			&::-moz-focus-inner {
				border-style: none;
				padding: 0;
			}

			/**
			 * Restore the focus styles unset by the previous rule.
			 */

			&:-moz-focusring {
				outline: 1px dotted ButtonText;
			}
		}

		/**
		 * Show the overflow in Edge.
		 */

		input {
			overflow: visible;
		}

		/**
		 * 1. Add the correct box sizing in IE 10-.
		 * 2. Remove the padding in IE 10-.
		 */

		[type="checkbox"],
		[type="radio"] {
			box-sizing: border-box; /* 1 */
			padding: 0; /* 2 */
		}

		/**
		 * Correct the cursor style of increment and decrement buttons in Chrome.
		 */

		[type="number"]::-webkit-inner-spin-button,
		[type="number"]::-webkit-outer-spin-button {
			height: auto;
		}

		/**
		 * 1. Correct the odd appearance in Chrome and Safari.
		 * 2. Correct the outline style in Safari.
		 */

		[type="search"] {
			-webkit-appearance: textfield; /* 1 */
			outline-offset: -2px; /* 2 */

			/**
			 * Remove the inner padding and cancel buttons in Chrome and Safari on macOS.
			 */

			&::-webkit-search-cancel-button,
			&::-webkit-search-decoration {
				-webkit-appearance: none;
			}
		}

		/**
		 * 1. Correct the inability to style clickable types in iOS and Safari.
		 * 2. Change font properties to `inherit` in Safari.
		 */

		::-webkit-file-upload-button {
			-webkit-appearance: button; /* 1 */
			font: inherit; /* 2 */
		}

		/**
		 * Correct the padding in Firefox.
		 */

		fieldset {
			padding: 0.35em 0.75em 0.625em;
		}

		/**
		 * 1. Correct the text wrapping in Edge and IE.
		 * 2. Correct the color inheritance from `fieldset` elements in IE.
		 * 3. Remove the padding so developers are not caught out when they zero out
		 *    `fieldset` elements in all browsers.
		 */

		legend {
			box-sizing: border-box; /* 1 */
			display: table; /* 1 */
			max-width: 100%; /* 1 */
			padding: 0; /* 3 */
			color: inherit; /* 2 */
			white-space: normal; /* 1 */
		}

		/**
		 * 1. Add the correct display in IE 9-.
		 * 2. Add the correct vertical alignment in Chrome, Firefox, and Opera.
		 */

		progress {
			display: inline-block; /* 1 */
			vertical-align: baseline; /* 2 */
		}

		/**
		 * Remove the default vertical scrollbar in IE.
		 */

		textarea {
			overflow: auto;
		}
	}

	@if _normalize-include(interactive) {
		/* Interactive
			 ========================================================================== */

		/*
		 * Add the correct display in Edge, IE, and Firefox.
		 */

		details {
			display: block;
		}

		/*
		 * Add the correct display in all browsers.
		 */

		summary {
			display: list-item;
		}

		/*
		 * Add the correct display in IE 9-.
		 */

		menu {
			display: block;

			@if $normalize-vertical-rhythm {
				/*
				 * 1. Set 1 unit of vertical rhythm on the top and bottom margin.
				 * 2. Set consistent space for the list style image.
				 */

				@include normalize-margin(1 0); /* 1 */
				padding: 0 0 0 $indent-amount; /* 2 */

				/**
				 * Turn off margins on nested lists.
				 */

				menu &,
				ol &,
				ul & {
					margin: 0;
				}
			}
		}
	}

	@if _normalize-include(scripting) {
		/* Scripting
			 ========================================================================== */

		/**
		 * Add the correct display in IE 9-.
		 */

		canvas {
			display: inline-block;
		}

		/**
		 * Add the correct display in IE.
		 */

		template {
			display: none;
		}
	}

	@if _normalize-include(hidden) {
		/* Hidden
			 ========================================================================== */

		/**
		 * Add the correct display in IE 10-.
		 */

		[hidden] {
			display: none;
		}
	}
}