var curCSS, iframe,
	// swappable if display is none or starts with table except "table", "table-cell", or "table-caption"
	// see here for display values: https://developer.mozilla.org/en-US/docs/CSS/display
	rdisplayswap = /^(none|table(?!-c[ea]).+)/,
	rmargin = /^margin/,
	rnumsplit = new RegExp( "^(" + core_pnum + ")(.*)$", "i" ),
	rnumnonpx = new RegExp( "^(" + core_pnum + ")(?!px)[a-z%]+$", "i" ),
	rrelNum = new RegExp( "^([+-])=(" + core_pnum + ")", "i" ),
	elemdisplay = { BODY: "block" },

cssShow = { position: "absolute", visibility: "hidden", display: "block" },
	cssNormalTransform = {
		letterSpacing: 0,
		fontWeight: 400
	},

cssExpand = [ "Top", "Right", "Bottom", "Left" ],
	cssPrefixes = [ "Webkit", "O", "Moz", "ms" ];

// return a css property mapped to a potentially vendor prefixed property
function vendorPropName( style, name ) {

// shortcut for names that are not vendor prefixed
	if ( name in style ) {
		return name;
	}

// check for vendor prefixed names
	var capName = name.charAt(0).toUpperCase() + name.slice(1),
		origName = name,
		i = cssPrefixes.length;

while ( i-- ) {
		name = cssPrefixes[ i ] + capName;
		if ( name in style ) {
			return name;
		}
	}

return origName;
}

function isHidden( elem, el ) {
	// isHidden might be called from jQuery#filter function;
	// in that case, element will be second argument
	elem = el || elem;
	return jQuery.css( elem, "display" ) === "none" || !jQuery.contains( elem.ownerDocument, elem );
}

// NOTE: we've included the "window" in window.getComputedStyle
// because jsdom on node.js will break without it.
function getStyles( elem ) {
	return window.getComputedStyle( elem, null );
}

function showHide( elements, show ) {
	var display, elem, hidden,
		values = [],
		index = 0,
		length = elements.length;

for ( ; index < length; index++ ) {
		elem = elements[ index ];
		if ( !elem.style ) {
			continue;
		}

values[ index ] = jQuery._data( elem, "olddisplay" );
		display = elem.style.display;
		if ( show ) {
			// Reset the inline display of this element to learn if it is
			// being hidden by cascaded rules or not
			if ( !values[ index ] && display === "none" ) {
				elem.style.display = "";
			}

// Set elements which have been overridden with display: none
			// in a stylesheet to whatever the default browser style is
			// for such an element
			if ( elem.style.display === "" && isHidden( elem ) ) {
				values[ index ] = jQuery._data( elem, "olddisplay", css_defaultDisplay(elem.nodeName) );
			}
		} else {

if ( !values[ index ] ) {
				hidden = isHidden( elem );

if ( display && display !== "none" || !hidden ) {
					jQuery._data( elem, "olddisplay", hidden ? display : jQuery.css( elem, "display" ) );
				}
			}
		}
	}

// Set the display of most of the elements in a second loop
	// to avoid the constant reflow
	for ( index = 0; index < length; index++ ) {
		elem = elements[ index ];
		if ( !elem.style ) {
			continue;
		}
		if ( !show || elem.style.display === "none" || elem.style.display === "" ) {
			elem.style.display = show ? values[ index ] || "" : "none";
		}
	}

return elements;
}

jQuery.fn.extend({
	css: function( name, value ) {
		return jQuery.access( this, function( elem, name, value ) {
			var styles, len,
				map = {},
				i = 0;

if ( jQuery.isArray( name ) ) {
				styles = getStyles( elem );
				len = name.length;

for ( ; i < len; i++ ) {
					map[ name[ i ] ] = jQuery.css( elem, name[ i ], false, styles );
				}

return map;
			}

return value !== undefined ?
				jQuery.style( elem, name, value ) :
				jQuery.css( elem, name );
		}, name, value, arguments.length > 1 );
	},
	show: function() {
		return showHide( this, true );
	},
	hide: function() {
		return showHide( this );
	},
	toggle: function( state ) {
		var bool = typeof state === "boolean";

return this.each(function() {
			if ( bool ? state : isHidden( this ) ) {
				jQuery( this ).show();
			} else {
				jQuery( this ).hide();
			}
		});
	}
});

jQuery.extend({
	// Add in style property hooks for overriding the default
	// behavior of getting and setting a style property
	cssHooks: {
		opacity: {
			get: function( elem, computed ) {
				if ( computed ) {
					// We should always get a number back from opacity
					var ret = curCSS( elem, "opacity" );
					return ret === "" ? "1" : ret;
				}
			}
		}
	},

// Exclude the following css properties to add px
	cssNumber: {
		"columnCount": true,
		"fillOpacity": true,
		"fontWeight": true,
		"lineHeight": true,
		"opacity": true,
		"orphans": true,
		"widows": true,
		"zIndex": true,
		"zoom": true
	},

// Add in properties whose names you wish to fix before
	// setting or getting the value
	cssProps: {
		// normalize float css property
		"float": "cssFloat"
	},

// Get and set the style property on a DOM Node
	style: function( elem, name, value, extra ) {
		// Don't set styles on text and comment nodes
		if ( !elem || elem.nodeType === 3 || elem.nodeType === 8 || !elem.style ) {
			return;
		}

// Make sure that we're working with the right name
		var ret, type, hooks,
			origName = jQuery.camelCase( name ),
			style = elem.style;

name = jQuery.cssProps[ origName ] || ( jQuery.cssProps[ origName ] = vendorPropName( style, origName ) );

// gets hook for the prefixed version
		// followed by the unprefixed version
		hooks = jQuery.cssHooks[ name ] || jQuery.cssHooks[ origName ];

// Check if we're setting a value
		if ( value !== undefined ) {
			type = typeof value;

// convert relative number strings (+= or -=) to relative numbers. #7345
			if ( type === "string" && (ret = rrelNum.exec( value )) ) {
				value = ( ret[1] + 1 ) * ret[2] + parseFloat( jQuery.css( elem, name ) );
				// Fixes bug #9237
				type = "number";
			}

// Make sure that NaN and null values aren't set. See: #7116
			if ( value == null || type === "number" && isNaN( value ) ) {
				return;
			}

// If a number was passed in, add 'px' to the (except for certain CSS properties)
			if ( type === "number" && !jQuery.cssNumber[ origName ] ) {
				value += "px";
			}

// Fixes #8908, it can be done more correctly by specifying setters in cssHooks,
			// but it would mean to define eight (for every problematic property) identical functions
			if ( !jQuery.support.clearCloneStyle && value === "" && name.indexOf("background") === 0 ) {
				style[ name ] = "inherit";
			}

// If a hook was provided, use that value, otherwise just set the specified value
			if ( !hooks || !("set" in hooks) || (value = hooks.set( elem, value, extra )) !== undefined ) {
				style[ name ] = value;
			}

} else {
			// If a hook was provided get the non-computed value from there
			if ( hooks && "get" in hooks && (ret = hooks.get( elem, false, extra )) !== undefined ) {
				return ret;
			}

// Otherwise just get the value from the style object
			return style[ name ];
		}
	},

css: function( elem, name, extra, styles ) {
		var val, num, hooks,
			origName = jQuery.camelCase( name );

// Make sure that we're working with the right name
		name = jQuery.cssProps[ origName ] || ( jQuery.cssProps[ origName ] = vendorPropName( elem.style, origName ) );

// gets hook for the prefixed version
		// followed by the unprefixed version
		hooks = jQuery.cssHooks[ name ] || jQuery.cssHooks[ origName ];

// If a hook was provided get the computed value from there
		if ( hooks && "get" in hooks ) {
			val = hooks.get( elem, true, extra );
		}

// Otherwise, if a way to get the computed value exists, use that
		if ( val === undefined ) {
			val = curCSS( elem, name, styles );
		}

//convert "normal" to computed value
		if ( val === "normal" && name in cssNormalTransform ) {
			val = cssNormalTransform[ name ];
		}

// Return, converting to number if forced or a qualifier was provided and val looks numeric
		if ( extra === "" || extra ) {
			num = parseFloat( val );
			return extra === true || jQuery.isNumeric( num ) ? num || 0 : val;
		}
		return val;
	},

// A method for quickly swapping in/out CSS properties to get correct calculations
	swap: function( elem, options, callback, args ) {
		var ret, name,
			old = {};

// Remember the old values, and insert the new ones
		for ( name in options ) {
			old[ name ] = elem.style[ name ];
			elem.style[ name ] = options[ name ];
		}

ret = callback.apply( elem, args || [] );

// Revert the old values
		for ( name in options ) {
			elem.style[ name ] = old[ name ];
		}

return ret;
	}
});

curCSS = function( elem, name, _computed ) {
	var width, minWidth, maxWidth,
		computed = _computed || getStyles( elem ),

// Support: IE9
		// getPropertyValue is only needed for .css('filter') in IE9, see #12537
		ret = computed ? computed.getPropertyValue( name ) || computed[ name ] : undefined,
		style = elem.style;

if ( computed ) {

if ( ret === "" && !jQuery.contains( elem.ownerDocument, elem ) ) {
			ret = jQuery.style( elem, name );
		}

// Support: Chrome <17, Safari 5.1
		// A tribute to the "awesome hack by Dean Edwards"
		// Chrome < 17 and Safari 5.0 uses "computed value" instead of "used value" for margin-right
		// Safari 5.1.7 (at least) returns percentage for a larger set of values, but width seems to be reliably pixels
		// this is against the CSSOM draft spec: http://dev.w3.org/csswg/cssom/#resolved-values
		if ( rnumnonpx.test( ret ) && rmargin.test( name ) ) {

// Remember the original values
			width = style.width;
			minWidth = style.minWidth;
			maxWidth = style.maxWidth;

// Put in the new values to get a computed value out
			style.minWidth = style.maxWidth = style.width = ret;
			ret = computed.width;

// Revert the changed values
			style.width = width;
			style.minWidth = minWidth;
			style.maxWidth = maxWidth;
		}
	}

return ret;
};

function setPositiveNumber( elem, value, subtract ) {
	var matches = rnumsplit.exec( value );
	return matches ?
		// Guard against undefined "subtract", e.g., when used as in cssHooks
		Math.max( 0, matches[ 1 ] - ( subtract || 0 ) ) + ( matches[ 2 ] || "px" ) :
		value;
}

function augmentWidthOrHeight( elem, name, extra, isBorderBox, styles ) {
	var i = extra === ( isBorderBox ? "border" : "content" ) ?
		// If we already have the right measurement, avoid augmentation
		4 :
		// Otherwise initialize for horizontal or vertical properties
		name === "width" ? 1 : 0,

val = 0;

for ( ; i < 4; i += 2 ) {
		// both box models exclude margin, so add it if we want it
		if ( extra === "margin" ) {
			val += jQuery.css( elem, extra + cssExpand[ i ], true, styles );
		}

if ( isBorderBox ) {
			// border-box includes padding, so remove it if we want content
			if ( extra === "content" ) {
				val -= jQuery.css( elem, "padding" + cssExpand[ i ], true, styles );
			}

// at this point, extra isn't border nor margin, so remove border
			if ( extra !== "margin" ) {
				val -= jQuery.css( elem, "border" + cssExpand[ i ] + "Width", true, styles );
			}
		} else {
			// at this point, extra isn't content, so add padding
			val += jQuery.css( elem, "padding" + cssExpand[ i ], true, styles );

// at this point, extra isn't content nor padding, so add border
			if ( extra !== "padding" ) {
				val += jQuery.css( elem, "border" + cssExpand[ i ] + "Width", true, styles );
			}
		}
	}

return val;
}

function getWidthOrHeight( elem, name, extra ) {

// Start with offset property, which is equivalent to the border-box value
	var valueIsBorderBox = true,
		val = name === "width" ? elem.offsetWidth : elem.offsetHeight,
		styles = getStyles( elem ),
		isBorderBox = jQuery.support.boxSizing && jQuery.css( elem, "boxSizing", false, styles ) === "border-box";

// some non-html elements return undefined for offsetWidth, so check for null/undefined
	// svg - https://bugzilla.mozilla.org/show_bug.cgi?id=649285
	// MathML - https://bugzilla.mozilla.org/show_bug.cgi?id=491668
	if ( val <= 0 || val == null ) {
		// Fall back to computed then uncomputed css if necessary
		val = curCSS( elem, name, styles );
		if ( val < 0 || val == null ) {
			val = elem.style[ name ];
		}

// Computed unit is not pixels. Stop here and return.
		if ( rnumnonpx.test(val) ) {
			return val;
		}

// we need the check for style in case a browser which returns unreliable values
		// for getComputedStyle silently falls back to the reliable elem.style
		valueIsBorderBox = isBorderBox && ( jQuery.support.boxSizingReliable || val === elem.style[ name ] );

// Normalize "", auto, and prepare for extra
		val = parseFloat( val ) || 0;
	}

// use the active box-sizing model to add/subtract irrelevant styles
	return ( val +
		augmentWidthOrHeight(
			elem,
			name,
			extra || ( isBorderBox ? "border" : "content" ),
			valueIsBorderBox,
			styles
		)
	) + "px";
}

// Try to determine the default display value of an element
function css_defaultDisplay( nodeName ) {
	var doc = document,
		display = elemdisplay[ nodeName ];

if ( !display ) {
		display = actualDisplay( nodeName, doc );

// If the simple way fails, read from inside an iframe
		if ( display === "none" || !display ) {
			// Use the already-created iframe if possible
			iframe = ( iframe ||
				jQuery("<iframe frameborder='0' width='0' height='0'/>")
				.css( "cssText", "display:block !important" )
			).appendTo( doc.documentElement );

// Always write a new HTML skeleton so Webkit and Firefox don't choke on reuse
			doc = ( iframe[0].contentWindow || iframe[0].contentDocument ).document;
			doc.write("<!doctype html><html><body>");
			doc.close();

display = actualDisplay( nodeName, doc );
			iframe.detach();
		}

// Store the correct default display
		elemdisplay[ nodeName ] = display;
	}

return display;
}

// Called ONLY from within css_defaultDisplay
function actualDisplay( name, doc ) {
	var elem = jQuery( doc.createElement( name ) ).appendTo( doc.body ),
		display = jQuery.css( elem[0], "display" );
	elem.remove();
	return display;
}

jQuery.each([ "height", "width" ], function( i, name ) {
	jQuery.cssHooks[ name ] = {
		get: function( elem, computed, extra ) {
			if ( computed ) {
				// certain elements can have dimension info if we invisibly show them
				// however, it must have a current display style that would benefit from this
				return elem.offsetWidth === 0 && rdisplayswap.test( jQuery.css( elem, "display" ) ) ?
					jQuery.swap( elem, cssShow, function() {
						return getWidthOrHeight( elem, name, extra );
					}) :
					getWidthOrHeight( elem, name, extra );
			}
		},

set: function( elem, value, extra ) {
			var styles = extra && getStyles( elem );
			return setPositiveNumber( elem, value, extra ?
				augmentWidthOrHeight(
					elem,
					name,
					extra,
					jQuery.support.boxSizing && jQuery.css( elem, "boxSizing", false, styles ) === "border-box",
					styles
				) : 0
			);
		}
	};
});

// These hooks cannot be added until DOM ready because the support test
// for it is not run until after DOM ready
jQuery(function() {
	if ( !jQuery.support.reliableMarginRight ) {
		jQuery.cssHooks.marginRight = {
			get: function( elem, computed ) {
				if ( computed ) {
					// WebKit Bug 13343 - getComputedStyle returns wrong value for margin-right
					// Work around by temporarily setting element display to inline-block
					return jQuery.swap( elem, { "display": "inline-block" },
						curCSS, [ elem, "marginRight" ] );
				}
			}
		};
	}

// Webkit bug: https://bugs.webkit.org/show_bug.cgi?id=29084
	// getComputedStyle returns percent when specified for top/left/bottom/right
	// rather than make the css module depend on the offset module, we just check for it here
	if ( !jQuery.support.pixelPosition && jQuery.fn.position ) {
		jQuery.each( [ "top", "left" ], function( i, prop ) {
			jQuery.cssHooks[ prop ] = {
				get: function( elem, computed ) {
					if ( computed ) {
						computed = curCSS( elem, prop );
						// if curCSS returns percentage, fallback to offset
						return rnumnonpx.test( computed ) ?
							jQuery( elem ).position()[ prop ] + "px" :
							computed;
					}
				}
			};
		});
	}

});

if ( jQuery.expr && jQuery.expr.filters ) {
	jQuery.expr.filters.hidden = function( elem ) {
		// Support: Opera <= 12.12
		// Opera reports offsetWidths and offsetHeights less than zero on some elements
		return elem.offsetWidth <= 0 && elem.offsetHeight <= 0;
	};

jQuery.expr.filters.visible = function( elem ) {
		return !jQuery.expr.filters.hidden( elem );
	};
}

// These hooks are used by animate to expand properties
jQuery.each({
	margin: "",
	padding: "",
	border: "Width"
}, function( prefix, suffix ) {
	jQuery.cssHooks[ prefix + suffix ] = {
		expand: function( value ) {
			var i = 0,
				expanded = {},

// assumes a single number if not a string
				parts = typeof value === "string" ? value.split(" ") : [ value ];

for ( ; i < 4; i++ ) {
				expanded[ prefix + cssExpand[ i ] + suffix ] =
					parts[ i ] || parts[ i - 2 ] || parts[ 0 ];
			}

return expanded;
		}
	};

if ( !rmargin.test( prefix ) ) {
		jQuery.cssHooks[ prefix + suffix ].set = setPositiveNumber;
	}
});

src/css.js

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