CSS3 interview questions and Answers

CSS is founded by Hakon Wium Lie and first released on December 17, 1996, as an official World Wide Web Consortium. CSS3 is the most advanced version of CSS and was released in June 1999.

There are three types of CSS available for users as following,

• Inline CSS: It contains CSS property in the body section attached with the element.
• Embedded CSS: Used to style a single HTML document uniquely.
• External CSS: It contains separate CSS files which contain only style property with the use of tag attributes.

The media query is a technique used to produce a tailored style sheet, better known as responsive web design, to desktops, tablets, laptops, and other mobile devices. We can also use media queries to specify certain styles required for printed documents or for screen readers.

It has a total of 10 media types supported it. Here are those:

• All - Intended for all devices
• Braille - Braille tactile feedback devices
• Aural – Used for speech synthesizers
• Embossed – Used for paged Braille printers
• Print – Applies for printed documents
• Handheld – Applies for handheld devices
• TTY – Used for media including a fixed-pitch character grid
• TV – Used for television-type devices
• Screen – Required for computer screens
• Projection – Used for projected presentations

CSS3 selector is a part of the CSS3 rule set that selects the content that the user wants to style.

There are different types of selectors available in CSS3.

• Universal Selector
• ID Selector
• Element Type Selector
• Class Selector
• Chile Combinator
• Descendant Combinator
• General Sibling Combinator
• Adjacent Sibling Combinator
• Attribute Selector
• Pseudo-element

The border-radius property is used to give any element rounded corners. This property defines the radius of an element’s edge.

• top-left corner, top-right corner, bottom-right corner, and bottom-left corner (Use of four values)
• top-left corner, top-right, and bottom-left corners, and bottom-right corner (Use of three values)
• top-left and bottom-right corners, and top-right and bottom-left corners (Use of two values)
• The value applies for all four corners equally

Users have to apply the border-image property to specify the image to be used as the border around an element.

The box-shadow property is used to add shadow effects around any element’s frame. Users can set multiple effects to a portion separated by commas. Usually, it is described by X and Y offsets relative to the part, color, and blur and spread radii.

CSS3 has plenty of new style properties in addition to it. Box-shadow: Used to effect the surround item containers on a webpage.

• The rounded corner effect
• Text shadow effect
• Background gradient effect

The CSS3 has included 147 additional color keywords introduced in it. CSS3 also offers a number of other color options to users such as HSLA, HSL, and RGBA. These color types also have the ability to declare semitransparent colors.

In CSS3, gradients let users display smooth transitions two or number of specified colors.

CSS defines two types of gradients, which are:

• Linear Gradients: It goes up/down/right/left/diagonally
• Radial Gradients: Usually defined by its center

CSS3 has a number of text related features introduced with it. Here are a few best of them:

• 3D text effect
• Text shadow effect
• Letterpress text effect
• Embossed CSS3 text effect
• Subtle CSS3 Text Style
• Date display technique
• Awesome Anaglyphic text effect
• Text rotation

In CSS3, the word-break property is used to specify how words should break when reaching the end of a line. The syntax for the word-break property is as follows:

CSS3 animations allow HTML element animation without using Flash or JavaScript. It lest elements gradually change form one style to another. The users must have to specify some keyframes for the animation to apply CSS3 animation.

In CSS3, the attr() function is used to retrieve the value of an attribute of the element selected and use it in the style sheet. This function also can be used on pseudo-elements, in which case pseudo-element's originating element attribute value will be returned.

The calc() function in CSS3 is used for simple calculations to determine CSS property values present right in CSS. It allows mathematical expressions with addition, subtraction, multiplication, and division to be used as component values.

In CSS3, the linear gradient starts at the top with the color red, transitioning to yellow and later to blue. It sets a linear gradient as the background image. Users have to define at least two color stops to create a linear gradient.

The CSS3 HSL() function is used to provide a color value when using CSS. It allows users to specify a color value by determining the hue, saturation, and light (which represent HSL) components of the color.

CSS3 Image sprites are a collection of images put in a single image to reduce the number of server requests, thereby saving bandwidth, and avoiding multiple server requests for each image.

#homeDiv {
   width: 32px;
   height: 32px;
   background: url(img_cssprites.gif) 0 0;
}

In the above example, we have combined 3 images into a single GIF, cssprites and we can use CSS to display a specific part as required.

In CSS, pseudo-element is used to style detailed and specific parts of an element.

For example, it may be used to:

• Style an element, letter or line.
• Insert content in an element before or after the content within the element.

It is a keyword added to a selector that lets you in styling a specific part of the selected element(s).

For example, ::first-line is used to change the font of the first line of a paragraph below.

p::first-line {
   color: blue;
   text-transform: uppercase;
}

The ::before the selector is used to inserting something before the content of any selected element. Whereas, the ::after selector to insert something after the content in a specified element.

Syntax for before selector:

::before {
   css declarations;
}

Syntax for After Selector:

::after {
   css declarations;
}

To apply CSS to all elements, use the CSS * Selector.

Example:

* {
   background-color: red;
}

This selects all the elements and changes their background color to blue.

Tweening is a term that's not used too often in CSS. It has its roots in computer animation and products like Flash. In tweening, rather than telling the program exactly how to render each frame, the animator/designer would tell the program what position the objects are in at two "keyframes" while the program figures out how to do the transition of the objects between the two mentioned points.

Here’s an example of sliding in an

element from the left side of a browser screen using tweening.

CSS can be applied to any web page using the following three ways:

• Inline CSS
• Internal Style Sheet
• External Style Sheets

In CSS, Inline CSS has the highest priority, followed by Internal/Embedded sheets, then followed by External CSS, having the least priority.

The grouping selector in CSS selects all the HTML elements with the same style definitions. This will be better to group the selectors, to minimize the code.

The comma is a grouping method, it selects all the matching nodes.

Example: div, span will match both <span> and <div> elements.

In CSS, the jQuery element + next Selector is used to select elements that are placed next to each other. Here’s an example to select the <a> element that are next to each <div> element.
$("div + a")

In CSS, the z-index property specifies the stack order of elements. An element having a greater stack order is placed in front of an element with a lower stack order.

Here’s its CSS Syntax:

z-index: auto|number|initial|inherit;

Here’s an example to set the z-index of an image:

img {
   position: fixed;
   left: 3px;
   top: 10px;
   z-index: -2;
}

White-space is a property within CSS which helps in controlling whitespace and other line breaks inside an element’s text. It has a default value of normal.

Here’s an example to display the different values within a white-space property:

p.e {
   white-space: nowrap;
}
p.f {
   white-space: normal;
}
p.g {
   white-space: pre;
}