CSS Getter

The .css() getter function can be applied to every DOM element on the page like the following:

// Rendered width in px as a string. ex: `150px`
// Notice the `as a string` designation - if you require a true integer, 
// refer to `$.width()` method
$("body").css("width"); 

This line will return the computed width of the specified element, each CSS property you provide in the parentheses will yield the value of the property for this $("selector") DOM element, if you ask for CSS attribute that doesn't exist you will get undefined as a response.

You also can call the CSS getter with an array of attributes:

$("body").css(["animation","width"]);

this will return an object of all the attributes with their values:

Object {animation: "none 0s ease 0s 1 normal none running", width: "529px"}

CSS Setter

The .css() setter method can also be applied to every DOM element on the page.

$("selector").css("width", 500);

This statement set the width of the $("selector") to 500px and return the jQuery object so you can chain more methods to the specified selector.

The .css() setter can also be used passing an Object of CSS properties and values like:

$("body").css({"height": "100px", width:100, "padding-top":40, paddingBottom:"2em"});

All the changes the setter made are appended to the DOM element style property thus affecting the elements' styles (unless that style property value is already defined as !important somewhere else in styles).

Numeric CSS properties can be incremented and decremented with the += and -= syntax, respectively, using the .css() method:

 // Increment using the += syntax
  $("#target-element").css("font-size", "+=10");
  
  // You can also specify the unit to increment by
  $("#target-element").css("width", "+=100pt");
  $("#target-element").css("top", "+=30px");
  $("#target-element").css("left", "+=3em");
  
  // Decrementing is done by using the -= syntax
  $("#target-element").css("height", "-=50pt");

Setting only one style:

$('#target-element').css('color', '#000000');

Setting multiple styles at the same time:

$('#target-element').css({
    'color': '#000000',
    'font-size': '12pt',
    'float': 'left',
});

To get an element's CSS property you can use the .css(propertyName) method:

var color    = $('#element').css('color');
var fontSize = $('#element').css('font-size');

Syntax

• .css( cssProperty ) // Get the rendered CSS property value
• .css( [cssProperty , ...] ) // Get values from Array of cssProperties
• .css( cssProperty, value ) // Set value
• .css( {cssProperty:value, ...} ) // Set properties and values
• .css( cssProperty, function ) // Expose the cssProperty to a callback function

Remarks

Rendered values

If a responsive unit is used (like "auto", "%", "vw" etc.), .css() will return the actual rendered value in px

.myElement{ width: 20%; }

var width = $(".myElement").css("width"); // "123px" 

Formatting properties and values

Properties can be defined using standard CSS formatting as String or using camelCase

"margin-bottom"
marginBottom

Values should be expressed in String. Numeric values are treated as px units internally by jQuery

.css(fontSize: "1em")
.css(fontSize: "16px")
.css(fontSize: 16)      // px will be used

As of jQuery 3 avoid using .show() and .hide()

According to this jQuery Blog post (opens new window), due to overhead and performance issues, you should no longer be using .show() or .hide().

If you have elements in a stylesheet that are set to `display: none`, the `.show()` method will no longer override that. So the most important rule for moving to jQuery 3.0 is this: Don’t use a stylesheet to set the default of `display: none` and then try to use `.show()` – or any method that shows elements, such as `.slideDown()` and `.fadeIn()` – to make it visible. If you need an element to be hidden by default, the best way is to add a class name like “hidden” to the element and define that class to be `display: none` in a stylesheet. Then you can add or remove that class using jQuery’s `.addClass()` and `.removeClass()` methods to control visibility. Alternately, you can have a `.ready()` handler call `.hide()` on the elements before they are displayed on the page. Or, if you really must retain the stylesheet default, you can use `.css("display", "block")` (or the appropriate display value) to override the stylesheet.