CSS3 (Cascading Style Sheets) is a styling language used to describe the appearance and layout of a web page. CSS3 selectors are used to target specific HTML elements on a page and apply styles to them. CSS3 provides various font properties to control the appearance of text on a web page, including font-size, font-family, and font-weight. CSS3 also offers a wide range of color options, including the use of RGB and HSL values, as well as the ability to set transparency levels. Background properties such as background-color and background-image can be used to set the background of an element. CSS3 borders provide options for controlling the width, style, and color of borders around elements. The box model refers to the rectangular structure used to represent an element on a web page, including its content, padding, borders, and margins. CSS3 animations allow for the creation of smooth and interactive transitions between styles, bringing more dynamic visual effects to web pages.

Topics covered:

  • What is CSS 3?
  • Selectors
  • Fonts
  • Colors
  • Backgrounds
  • Borders
  • Box Model
  • Animations

Video (in Bulgarian)

Presentation Content

What is CSS 3?

  • Cascading Style Sheets level 3 is the most recent iteration of CSS
  • It is divided into several separatedocuments called “modules”
  • CSS 3 has not been approved as a specification, but there are already a lot of properties that are supported in various browsers.
  • The earliest CSS 3 drafts were published in June 1999

Attribute Selectors

  • E[foo^=“bar”]
    • An E element whose “foo” attribute value begins exactly with the string “bar”
    • Example: a[src ^=" https://"]
  • E[foo$=“bar”]
    • An E element whose “foo” attribute value ends exactly with the string “bar”
  • E[foo*=“bar”]
    • An E element whose “foo” attribute value contains the substring “bar”

Structural Pseudo-classes

  • :root
    • The root of the document
  • E:nth-child(n)
    • An E element, the n-th child of its parent
  • E:nth-last-child(n)
    • An E element, the n-th child of its parent, counting from the last on
  • E:nth-of-type(n)
    • An E element, the n-th sibling of its type
  • E:nth-last-of-type(n)
    • An E element, the n-th sibling of its type, counting from the last one
  • E:last-child
    • An E element, last child of its parent
  • E:first-of-type
    • An E element, first sibling of its type
  • E:last-of-type
    • An E element, last sibling of its type
  • E:only-child
    • An E element, only child of its parent
  • E:only-of-type
    • An E element, only sibling of its type
  • E:empty
    • An E element that has no children (including text nodes)
  • More detailed descriptions:

The UI Element States Pseudo-classes

  • E:enabled
    • A user interface element E which is enabled
  • E:disabled
    • A user interface element E which is disabled
  • E:checked
    • A user interface element E which is checked (for instance a radio-button or checkbox)

Other CSS 3 Selectors

  • E:target
    • An E element being the target of the referring URI
  • E:not(s)
    • An E element that does not match simple selector
  • E ~ F
    • An F element preceded by an E element

Font Embeds

  • Use @font-face to declare font
  • Point to font file on server
  • Call font with font-family
  • Use font embedding instead of images
@font-face {
    font-family: SketchRockwell;
    src: url('SketchRockwell-Bold.ttf');
.my_CSS3_class {
    font-family: SketchRockwell;
    font-size: 3.2em;

Text Shadow

  • Applies shadow to text
  • Syntax: text-shadow: <horizontal-distance> <vertical-distance> <blur-radius> <shadow-color>;
  • Do not alter the size of a box
text-shadow: 2px 2px 7px #000000;

Text Overflow

  • Specifies what should happen when text overflows the containing element
  • Syntax: text-overflow: <value>;
  • Possible values:
    • ellipsis - Display ellipses to represent clipped text
    • clip - Default value, clips text

Word Wrapping

  • Allows long words to be able to be broken and wrap onto the next line
  • Syntax: word-wrap: <value>;
  • Possible values:
    • normal
    • break-word
  • Supported in all major browsers


  • Sets the opacity level for an element
  • Syntax: opacity: <value>;
  • Value from 0.0 (fully transparent) to 1.0
  • The opacity is supported in all major browsers.
  • Note: IE8 and earlier supports an alternative, the filter property: filter: Alpha(opacity=50).
  • Example:
    <img src="img.jpg" style= " opacity: 0.4; filter: alpha(opacity=40)" />

RGBA Colors

  • Standard RGB colors with an opacity value for the color (alpha channel)
  • Syntax: rgba(<red>, <green>, <blue>, <alpha>)
  • The range for red , green and blue is between integers 0 and 255
  • The range for the alpha channel is between 0.0 and 1.0
  • Example: rgba(255, 0, 0, 0.5)

HSL Colors

  • Hue is a degree on the color wheel
    • 0 (or 360) is red, 120 is green, 240 is blue
  • Saturation is a percentage value
    • 100% is the full color
  • Lightness is also a percentage
    • 0% is dark (black)
    • 100% is light (white)
    • 50% is the average

HSLA Colors

  • HSLA allows a fourth value, which sets the Opacity (via the Alpha channel) of the element.
  • As RGBA is to RGB, HSLA is to HSL
  • Supported in IE9+, Firefox 3+, Chrome, Safari, and in Opera 10+
  • Example:
    • hsla(0, 100%, 50%, 0.5)

Gradient Backgrounds

  • Gradients are smooth transitions between two or more specified colors
  • Use of CSS gradients can replace images and reduce download time
  • Create a more flexible layout, and look better while zooming
  • Supported in all major browsers via different keywords
  • This is still an experimental feature

Gradient Backgrounds Example

/* Firefox 3.6+ */
background: -moz-linear-gradient(100% 100% 90deg,   
  #FFFF00, #0000FF);
/* Safari 4-5, Chrome 1-9 */
background: -webkit-gradient(linear, 0% 0%, 0% 
  100%, from(#0000FF), to(#FFFF00));
/* Safari 5.1+, Chrome 10+ */
background: -webkit-linear-gradient(#FFFF00, 
/* Opera 11.10+ */
background: -o-linear-gradient(#2F2727, #0000FF);

Multiple Backgrounds

  • CSS3 allows multiple background images
  • Simple comma-separated list of images
  • Supported in Firefox (3.6+), Chrome (1.0/1.3+), Opera (10.5+) and Internet Explorer (9.0+)
  • Comma separated list for the other properties
background-image: url(sheep.png), url(grass.png);

Border color

  • Allows you to create cool colored borders
  • Only Firefox supports this type of coloring
border: 8px solid #000;
-moz-border-bottom-colors: #555 #666 #777 #888 #999 #aaa #bbb #ccc;
-moz-border-top-colors: #555 #666 #777 #888 #999 #aaa #bbb #ccc;
-moz-border-left-colors: #555 #666 #777 #888 #999 #aaa #bbb #ccc;
-moz-border-right-colors: #555 #666 #777 #888 #999 #aaa #bbb #ccc;

Border image

  • Defines an image to be used instead of the normal border of an element
  • Split up into a couple of properties
  • Example:
    • The border-image property has 3 parts:
    border-image: url(border-image.png) 25% repeat;
  • More detailed description:

Border radius

  • Allows web developers to easily utilize rounder corners in their design elements
  • Widespread browser support
  • Syntax:
    border-*-*-radius: [<length>|<%>][<length>|<%>]? 
  • Example:
    -moz-border-radius: 15px;
    border-radius: 15px;
    background-color: #FF00FF;

Box shadow

  • Allows to easily implement multiple drop shadows (outer or inner) on box elements
  • Specifying values for color, size, blur and offset
  • Example:
    -moz-box-shadow: 10px 10px 5px #888;
    -webkit-box-shadow: 10px 10px 5px #888;
    box-shadow: 10px 10px 5px #888;

CSS3 box-sizing

  • Determine whether you want an element to render it’s borders and padding within its specified width, or outside of it.
  • Possible values:
    • box-sizing: content-box (default)box width: 288 pixels + 10 pixels padding and 1 pixel border on each side = 300 pixels
    • box-sizing: border-box box width: 300 pixels, including padding and borders

CSS3 box-sizing (Example)

  • Example: Box with total width of 300 px (including paddings and borders)
width: 300px;
border: 1px solid black;
padding: 5px;

/* Firefox */
-moz-box-sizing: border-box;
/* WebKit */
-webkit-box-sizing: border-box;
/* Opera 9.5+, Google Chrome */
box-sizing: border-box;

CSS 3 Flexible Box Model

  • The flexible box model determines the way boxes are distributed inside other boxes and the way they share the available space.
  • New values for “display” property:
    • flexbox
    • inline-flexbox
  • This box model is still under development
  • Still not supported in major browsers

CSS 3 Box Model Properties

  • flex-direction
    • Specifies how flexbox items are placed
  • flex-order
    • May be used to change the ordering of the elements. Elements are sorted by this value.
  • flex-pack
    • Defines the flexibility of packing spaces
  • flex-align
    • Changes the way free space is allocated

CSS 3 flex-direction

  • The flex-direction property specifies how flexbox items are placed in the flexbox.
  • Possible values:
    • lr – Displays elements from left to right
    • rl – Displays elements from right to left
    • tb – Displays elements from top to bottom
    • bt – Displays elements from bottom to top
    • inline and inline-reverse
    • block and block-reverse


  • Works in all webkit browsers
  • Example:
    @keyframes resize {
        0% {...}
        50% {...}
        100% {...}
    #box {
        animation-name: resize;
        animation-duration: 1s;
        animation-iteration-count: 4;
        animation-direction: alternate;     animation-timing-function: ease-in-out;


  • Add an effect when changing from one style to another
  • Different timing functions:
    • ease, ease-in, ease-out, ease-in-out, linear
  • Example:
    #id_of_element {
        -webkit-transition: all 1s ease-in-out;     -moz-transition: all 1s ease-in-out;
        -o-transition: all 1s ease-in-out;
        -ms-transition: all 1s ease-in-out;     transition: all 1s ease-in-out;

2D Transformations

  • 2D transforms are widely supported
  • Skew – skew element
    • transform: skew(35deg);
  • Scale – scale element
    • transform: scale(1,0.5);
  • Rotate – rotates element
    • transform: rotate(45deg);
  • Translate – moves element
    • transform: translate(10px, 20px);

3D Transformations

  • 3D transforms are similar to 2D transforms
  • Only work in Safari and Chrome
  • X, Y and Z transformation
    • transform: rotateX(180deg);
    • transform: rotateY(180deg);
    • transform: rotateZ(180deg);
    • perspective: 800;
    • perspective-origin: 50% 100px;
    • translate3d, scale3d


  • Using CSS3 make a rotating 3D Rubik Cube.
  • Using CSS3 make a text that is pulsing, i.e. gets bigger, then smaller, etc. while blinking with different colors.
  • Using CSS3 make a text bouncing around the screen (the browser).
    • Hint: the text should change its position