Last modified: March 18, 2018

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CSS

Key Points about CSS

Skills Every CSS Developer Should Have

  1. Proficiency in basic styling is fundamental, covering the adjustment of visual properties such as colors, font sizes, line spacing, and borders to enhance readability and aesthetics.
  2. Layout and positioning expertise is essential, as developers must be skilled in tools like Flexbox and CSS Grid for building responsive and well-structured designs across various screen sizes.
  3. An understanding of CSS selectors is necessary for efficiently targeting and styling specific HTML elements, classes, and IDs without overcomplicating the code.
  4. Regular use of resources like MDN (Mozilla Developer Network) is valuable for staying informed on CSS standards, learning best practices, and understanding how to leverage newer features effectively.
  5. Being able to build and customize components is crucial, as it allows developers to recreate UI elements, like buttons, cards, and modals, purely with CSS for both design precision and responsiveness.

Integrating CSS with HTML

You can add CSS to your HTML documents in three primary ways:

  1. Inline Styles: This method involves adding CSS directly within the HTML tags. However, it's not recommended for larger styles or for maintaining consistency across pages.

<element style="property: value;">

  1. Internal (or Embedded) Styles: You can define styles for a particular page within the <style> tags in the <head> section. This is suitable for page-specific styles.

<head>
<style>
	selector { property: value; }
    </style>
</head>

  1. External Styles: This is the most commonly used method for large websites. Styles are defined in a separate .css file and then linked to the HTML document. This way, one stylesheet can be used across multiple pages, ensuring consistency and ease of maintenance.

<head>
<link href="style.css" rel="stylesheet"/>
</head>

Understanding Selectors

CSS Selectors play a pivotal role in defining which HTML elements should receive specific styles. By combining different types of selectors and properties, web developers can create intricate designs and layouts.

Selectors and Properties

In CSS, a basic rule-set consists of a selector and a declaration block. The declaration block contains properties and their values.

selector {
    property_1: value_1;
    property_2: value_2;
    /* ... and so on */
}

Different Types of CSS Selectors

There's a plethora of selectors in CSS, each serving a distinct purpose. Here are some of the fundamental selectors:

  1. Universal Selector: It targets every element on the page. Often used with caution due to its broad reach.

* {
    font-family: Arial, sans-serif;
}

  1. Element (or Type) Selector: Targets all instances of a specific element type.

h1 {
    color: green;
}

  1. ID Selector: Targets a specific element based on its id attribute. Each ID should be unique within a page.

#header_1 {
    color: red;
}
#header_2 {
    color: blue;
}

  1. Class Selector: Targets elements based on their class attribute. Useful for grouping elements with similar styles.

.highlight {
    color: yellow;
}

  1. Child Selector: Targets direct children of a specified element. It doesn't affect nested or inner elements.

#gallery > p {
    font-weight: bold;
}

  1. Descendant Selector: Targets all nested elements (or descendants) that match the specified selector, not just direct children.

#container div {
border: 1px solid black;
}

Additionally, CSS offers combinations of selectors, pseudo-classes, pseudo-elements, and more, giving developers a wide array of tools for precise styling.

Introduction to Pseudo-selectors

Pseudo-selectors, also known as pseudo-classes, allow us to style elements based on their state or position, rather than just their type or attribute.

Consider the following HTML and CSS:

<div id="gallery">
<a href="https://www.google.com">Google</a>
<a href="https://www.yahoo.com">Yahoo</a>
</div>

css

#gallery {
    color: red;
}

#gallery p {
    color: blue;
}

#gallery a:hover {
    color: green;
}

In the example above, the color of text in the #gallery is red. However, paragraphs inside it are blue. Additionally, links turn green when hovered.

Common Pseudo-selectors

Pseudo-selectors, often termed pseudo-classes, allow developers to target and style HTML elements based on specific conditions, states, or positions rather than solely on their tags or attributes.

Below is a list of commonly-used pseudo-selectors, each paired with a brief description and a link to its documentation on MDN for deeper insights:

Pseudo-Class Description MDN Documentation
:active Targets elements currently being activated by the user (e.g., clicked links). MDN Docs
:focus Highlights the currently focused element, commonly used with form fields. MDN Docs
:hover Styles an element when a user hovers over it with their cursor. MDN Docs
:link Targets hyperlinks that haven't been visited by the user. MDN Docs
:visited Selects links that have been visited by the user. MDN Docs
:checked Targets checked elements like radio buttons or checkboxes. MDN Docs
:first-child Targets the first child element inside a parent element. MDN Docs
:last-child Selects the last child element within a parent. MDN Docs
:nth-child(n) Styles elements based on their position within a parent element. MDN Docs
:disabled Targets disabled form controls. MDN Docs for :disabled
:enabled Targets enabled form controls. MDN Docs for :enabled
:not(selector) Selects elements that do not match a specified selector. MDN Docs

Inheritance and Specificity in CSS

In the world of CSS, it's crucial to understand how rules cascade and how specificity works. Specificity determines which CSS rule is applied to an element when there are multiple conflicting rules.

Specificity Hierarchy

When two or more CSS rules target the same element but have conflicting styles, the specificity hierarchy determines which rule is applied:

  1. IDs
  2. Classes, attributes, and pseudo-classes
  3. Elements and pseudo-elements

Visualized:

ids > classes, attributes, pseudo-classes > elements, pseudo-elements

Useful tools like Specificity Calculator can help understand and calculate the specificity of your selectors.

Pseudo-elements in CSS

Pseudo-elements are a powerful feature in CSS, allowing you to style certain parts of a document, or to virtually insert content into the document, without altering the actual HTML structure.

Concept

Pseudo-elements are different from pseudo-classes. While pseudo-classes select elements based on their state or position in relation to others (like :hover or :nth-child), pseudo-elements target specific parts of an element, like the first line or first letter, or they can virtually insert content before or after an element's content.

Consider this sample:

<div id="gallery">

<a href="https://www.google.com">Google</a>


<a href="https://www.yahoo.com">Yahoo</a>

</div>

And the accompanying styles:

#gallery {
    color: black;
}

#gallery p::first-letter {
    font-size: 20px;
    color: red;
}

#gallery a:hover::before {
    content: "→ ";
    color: green;
}

In this illustration, the ::first-letter pseudo-element targets and enlarges the initial letter of each paragraph, coloring it red. The ::before pseudo-element introduces an arrow symbol (→) preceding the anchor text, appearing when hovered.

Common Pseudo-elements

Pseudo-elements target specific parts of elements or create virtual content around them. They're instrumental in achieving certain design patterns and effects without altering the actual HTML content.

Pseudo-Element Description MDN Documentation
::before Inserts virtual content before an element's actual content. Typically used with the content property. MDN Docs
::after Inserts virtual content after an element's content. Often used with the content property. MDN Docs
::first-letter Targets the first letter of block-level elements, useful for drop cap styling. MDN Docs
::first-line Applies styles to the first line of text within block-level elements. MDN Docs

Noteworthy Points:

Box Model

The CSS Box Model is a fundamental concept in web design that describes the rectangular boxes which are generated for elements in the document tree and laid out according to the visual formatting model. Each box has a content area and optional surrounding padding, border, and margin areas.

Box
.......................
.  Margin             . 
.  -----------------  .
.  | Padding       |  .
.  |  ###########  |  .
.  |  # Element #  |  .
.  |  ###########  |  .
.  |               |  .
.  -----------------  .
.                     .
.......................

Let's take a look at a complete example:

<div id="box">
Content
</div>

#box {
	width: 100px;
	height: 100px;
	padding: 10px;
	margin: 10px;
	border: 1px solid black;
}

The above example defines a box with a content area of 100x100px, a padding of 10px, a margin of 10px, and a black border with a width of 1px.

Margins

Margins create space around an element, separating it from other elements.

Property Description Values MDN Documentation
margin-top Defines the space above the element. auto, length, percentage MDN Docs
margin-right Defines the space to the right of the element. auto, length, percentage MDN Docs
margin-bottom Defines the space below the element. auto, length, percentage MDN Docs
margin-left Defines the space to the left of the element. auto, length, percentage MDN Docs

Padding

Padding creates space within an element, between the content and its border.

Property Description Values MDN Documentation
padding-top Defines the space between the content and the top border of the element. length, percentage MDN Docs
padding-right Defines the space between the content and the right border of the element. length, percentage MDN Docs
padding-bottom Defines the space between the content and the bottom border of the element. length, percentage MDN Docs
padding-left Defines the space between the content and the left border of the element. length, percentage MDN Docs

Border

Borders surround an element, giving it structure and sometimes helping it stand out. You can define the width, style, color, and even use images as borders.

Property Description Values MDN Documentation
border-width Defines the thickness of the border. auto, length MDN Docs
border-style Determines the pattern or design of the border. none, hidden, dotted, dashed, solid, double, groove, ridge, inset, outset MDN Docs
border-color Sets the color of the border. Color name, hex, rgba, etc. MDN Docs
border-radius Creates rounded borders. length (can set each corner individually) MDN Docs
border-image Uses an image as the border. none, image source, slice, width, outset, repeat MDN Docs

Outline

Outlines are similar to borders but don't take up space. They're often used for focus styles and other UI states.

Property Description Values MDN Documentation
outline-width Defines the thickness of the outline. auto, length MDN Docs
outline-style Determines the pattern or design of the outline. none, hidden, dotted, dashed, solid, double, groove, ridge, inset, outset MDN Docs
outline-color Sets the color of the outline. Color name, hex, rgba, etc. MDN Docs

Advanced Tips

When setting the dimensions of an element, be cautious of extremes. An element that is either too small or too large can disrupt the layout and aesthetics of a page. In these cases, special values such as max-content, min-content, and fit-content are valuable:

Flexbox

Flexbox, short for "Flexible Box Layout", is a design model in CSS that allows you to design complex layout structures with a more efficient and predictable way than traditional models, especially when dealing with different screen sizes and dynamic content.

Flex Container vs. Flex Items

When an element is defined as a flex container (using display: flex or display: inline-flex), its children automatically become flex items. Flexbox involves two sets of properties:

  1. Container Properties: These are set on the flex container.

Property Description Values
display Initiates the flex context, allowing use of Flexbox properties. flex, inline-flex
flex-direction Defines the direction of the main axis, controlling the flow of flex items. row, row-reverse, column, column-reverse
flex-wrap Determines whether flex items should wrap onto multiple lines when there isn’t enough space. nowrap, wrap, wrap-reverse
justify-content Aligns items along the main axis within the container. flex-start, flex-end, center, space-between, space-around, space-evenly
align-items Aligns items along the cross axis within the container. flex-start, flex-end, center, baseline, stretch
align-content Aligns lines of flex items when there is extra space on the cross axis. flex-start, flex-end, center, space-between, space-around, stretch

  1. Item Properties: These are set on the flex items.

Property Description Values
flex Shorthand for setting flex-grow, flex-shrink, and flex-basis. none, auto, <flex-grow> <flex-shrink> <flex-basis>
align-self Allows an individual flex item to override the container’s align-items property. auto, flex-start, flex-end, center, baseline, stretch
order Specifies the order of the flex item within the container. Integer values, e.g., 0 (default), 1, -1, etc.
flex-basis Sets the initial main size of a flex item before any space distribution by flex-grow and flex-shrink. auto, length, percentage
flex-grow Specifies how much a flex item will grow relative to the rest of the flex items. Integer values, e.g., 0 (default), 1, 2, etc.
flex-shrink Specifies how much a flex item will shrink relative to the rest of the flex items. Integer values, e.g., 1 (default), 0, etc.

Understanding the Axes

Flexbox layout revolves around two axes: the main axis and the cross axis.

<---------------------- axis ---------------------->
##########    ##########    ##########    ##########
# Elem 1 #    # Elem 2 #    # Elem 3 #    # Elem 4 #
##########    ##########    ##########    ##########

The cross axis, in this case, runs vertically.

Ë„     ##########
|     # Elem 1 #
|     ##########
|
|     ##########
a     # Elem 2 #
x     ##########
i
s     ##########
|     # Elem 3 #
|     ##########
|
|     ##########
|     # Elem 4 #
|     ##########
Ë…

The cross axis, in this setup, runs horizontally.

HTML:

<div class="container">
<div class="row">
<div class="col-md-4">
<div class="box">
<h1>Box 1</h1>
</div>
</div>
<div class="col-md-4">
<div class="box">
<h1>Box 2</h1>
</div>
</div>
<div class="col-md-4">
<div class="box">
<h1>Box 3</h1>
</div>
</div>
</div>
</div>

CSS:

.container {
   display: flex;
   justify-content: center;
   align-items: center;
}

.row {
   display: flex;
   flex-direction: row;
   justify-content: center;
   align-items: center;
}

.col-md-4 {
   margin: 10px;
}

.box {
   background-color: #f5f5f5;
   padding: 20px;
   border-radius: 5px;
   box-shadow: 0px 0px 5px #ccc;
}

In the above example, we have a container with a row of three boxes. The boxes are all the same size, but the container is set to flex-direction: row. This means that the boxes will be laid out horizontally. The boxes are also centered in the container.

Links:

Flexbox Properties

Flexbox introduces a set of properties that provide a more efficient and predictable way to layout, align, and distribute space among items in a container, even when their sizes are unknown or dynamic.

Flex Containers

To create a flex container, use the display property:

Property Description Values MDN Documentation
display Determines the element's inner and outer display type. flex (block-level) , inline-flex (inline-level) MDN Docs

Ordering and Orientation

Control the order in which items appear and their directional flow:

Property Description Values MDN Documentation
order Specifies the order of the flex item relative to its siblings. <number> (default: 0) MDN Docs
flex-direction Defines the direction of the main axis, determining the orientation of flex items. row, row-reverse, column, column-reverse MDN Docs
flex-wrap Specifies whether flex items wrap onto multiple lines or columns. nowrap, wrap, wrap-reverse MDN Docs
flex-flow Shorthand property for setting both flex-direction and flex-wrap. <flex-direction> || <flex-wrap> MDN Docs

Alignment and Justification

Determine how items are aligned and spaced within the flex container:

Property Description Values MDN Documentation
align-items Aligns flex items along the cross axis of the flex container. flex-start, flex-end, center, baseline, stretch MDN Docs
align-content Aligns flex lines within the container when there’s extra space in the cross-axis. flex-start, flex-end, center, space-between, space-around, stretch MDN Docs
justify-content Defines how flex items are spaced along the main axis. flex-start, flex-end, center, space-between, space-around, space-evenly MDN Docs

Flexibility of Items

Define how flex items grow and shrink:

Property Description Values MDN Documentation
flex Shorthand to set the flex-grow, flex-shrink, and flex-basis properties. <flex-grow> <flex-shrink> <flex-basis> MDN Docs
flex-grow Specifies the flex item’s ability to grow relative to other items. <number> (default: 0) MDN Docs
flex-shrink Defines the flex item’s ability to shrink relative to other items. <number> (default: 1) MDN Docs
flex-basis Sets the default size of a flex item before space distribution among items. auto, <length>, <percentage> MDN Docs

Leveraging these properties allows for sophisticated layout designs that adapt gracefully across different screen sizes and resolutions.

Noteworthy Points:

Special Styling Elements

Certain elements in CSS come with a unique set of styling options. One such element is the list, with its associated markers.

Lists & Markers

In web design, lists are ubiquitous. CSS provides granular control over the appearance and positioning of list items and their markers.

Property Description Values MDN Documentation
list-style Defines an element's list style, including type, position, and image. none, <list-style-type> <list-style-position> <list-style-image> MDN Docs
list-style-type Specifies the type of list marker. disc, circle, square, decimal, lower-roman, upper-roman, etc. MDN Docs
list-style-position Determines the marker’s position relative to the list item content. inside, outside MDN Docs
list-style-image Allows using an image as the list item marker. url("path_to_image") MDN Docs
marker-offset (Deprecated) Sets the distance between the marker and the nearest border edge of the list item box. auto, <length> MDN Docs
marker-start (Deprecated) Specifies a marker for the start of lines, replaced by SVG marker attribute. Depends on SVG marker settings MDN Docs

HTML:

<ul>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
</ul>

CSS: 

ul {
   list-style-type: none;
}

li {
   display: inline-block;
   margin: 10px;
   padding: 10px;
   border: 1px solid #ccc;
   border-radius: 5px;
   box-shadow: 0px 0px 5px #ccc;
}

In the above example, we have a list with three items. The list is set to display: inline-block. This means that the items will be displayed horizontally as opposed to the default vertical. The items are distinguished by a border and a box-shadow.

Table

Tables in CSS are designed to structure tabular data. They come with a rich set of properties that offer detailed styling options to enhance their appearance and usability.

Property Description Values MDN Documentation
table-layout Determines the algorithm used to layout the table cells, rows, and columns. auto, fixed MDN Docs
border-collapse Specifies whether cell borders are collapsed into a single border or detached. collapse, separate MDN Docs
border-spacing Defines spacing between the borders of adjacent cells when border-collapse is set to separate. <length> <length> (e.g., 2px 4px) MDN Docs
caption-side Specifies the position of the table's caption. top, bottom MDN Docs
empty-cells Determines the visibility of borders and backgrounds of empty cells. show, hide MDN Docs

HTML:

<table>
<tr>
<th>Header 1</th>
<th>Header 2</th>
<th>Header 3</th>
</tr>
<tr>
<td>Cell 1</td>
<td>Cell 2</td>
<td>Cell 3</td>
</tr>
<tr>
<td>Cell 1</td>
<td>Cell 2</td>
<td>Cell 3</td>
</tr>
</table>

CSS: 

table {
   border-collapse: collapse;
   border-spacing: 0;
}

th, td {
   padding: 10px;
   border: 1px solid #ccc;
   border-radius: 5px;
   box-shadow: 0px 0px 5px #ccc;
}

Text

Text is a fundamental aspect of web design, and CSS offers an extensive suite of properties to style text with precision. From basic color settings to intricate shadow effects, text styling can be as simple or as detailed as the design requires.

Property Description Values MDN Documentation
color Specifies the color of the text. HEX, RGB, RGBA, HSL, or named colors MDN Docs
direction Sets the direction in which text is written. ltr, rtl MDN Docs
letter-spacing Adjusts the space between characters. Units like px, em, rem MDN Docs
line-height Determines the height of a line box. normal, Number values, Units like px, em MDN Docs
text-align Aligns the inline content, such as text. start, end, left, right, center, justify MDN Docs
text-decoration Adds decorative lines to text. none, underline, overline, line-through MDN Docs
text-indent Indents the first line of a text block. Units like px, em, rem MDN Docs
text-transform Controls the capitalization of text. capitalize, uppercase, lowercase, none MDN Docs
vertical-align Sets the vertical positioning of an element relative to its parent or line height. baseline, sub, super, top, text-top, middle, bottom, text-bottom, Units like px, em MDN Docs
white-space Specifies how whitespace inside an element is handled. normal, pre, nowrap, pre-wrap, pre-line MDN Docs
word-spacing Adjusts the space between words. Units like px, em, rem MDN Docs
text-outline (Non-standard) Defines an outline for the text. none, color, width, style MDN Docs
text-overflow Specifies how overflowed content is signaled to the user. clip, ellipsis MDN Docs
text-shadow Adds shadow effects to the text. color, offset-x, offset-y, blur-radius MDN Docs
text-wrap (Non-standard) Specifies line breaking rules. normal, none, break-word MDN Docs
word-break Controls how lines should break in case of long words or overflow. normal, break-all, keep-all MDN Docs
word-wrap Specifies whether to break words when they overflow the content box. normal, break-word MDN Docs

HTML:

This is a paragraph.

CSS:

p {
   font-family: sans-serif;
   font-size: 1.5em;
   font-weight: bold;
   color: #333;
   text-align: center;
   text-shadow: 0px 0px 5px #ccc;
}

In the above example, we have a paragraph. The text in the paragraph is set to be bold, centered and surrounded by a shadow. The font-family is selected to be sans-serif and the font-size is set to 1.5em.

Style

CSS provides a suite of generic styling properties that can be applied universally across elements. Two commonly used properties are font and color. While font dictates the appearance and style of text, color sets the foreground color for text and other graphical elements.

Font

Fonts play a pivotal role in establishing the visual identity of a website. With the advent of web fonts, designers are no longer restricted to a few standard system fonts. Today, a vast collection of fonts can be easily integrated into web projects to achieve the desired typography.

There are numerous platforms that offer free and premium web fonts:

Steps to Incorporate Custom Fonts:

  1. Navigate to a web fonts platform and select a desired font.
  2. Obtain the link or @font-face code snippet for the chosen font.
  3. Insert the link or code snippet into the <head> section of your HTML file.
  4. Reference the font in your CSS using the font-family property.

Property Description Values MDN Documentation
font-style Dictates the style of a font. normal, italic, oblique MDN Docs
font-weight Determines the thickness of characters. normal, bold, bolder, lighter, 100 - 900 MDN Docs
font-size Specifies the size of the font. Units like px, em, rem, %, etc. MDN Docs
font-family Defines which font should be used. Font names in quotes, e.g., "Helvetica, sans-serif" MDN Docs
font-variant Controls font variants, mainly for capitalized text. normal, small-caps MDN Docs

Example:

p { 
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 20px;
  font-weight: bold;
  font-style: italic;
  text-decoration: underline;
  text-decoration-style: wavy;
  text-decoration-color: red;
}

In the example above, the font-family is set to "Helvetica Neue", which is a font that is available on most web browsers. The font-size is set to 20px, the font-weight is bold, and the font-style is italic. The text is underlined with a wavy style, and the underline color is red.

Aditional explanations

Web fonts have reshaped the landscape of web typography. Platforms like Google Fonts and Adobe Fonts host a myriad of fonts, ensuring websites can have unique and tailored typography. When using custom fonts, it's vital to ensure they're web-optimized for performance and that fallback fonts are specified to cater to users with limited font access or slow internet connections.

Colors

In web design, colors have a profound influence on user experience and branding. CSS provides diverse methods to assign colors to HTML elements. Besides color, you can also control an element's transparency or opacity, impacting how underlying content might be visible through it.

Property Description Values MDN Documentation
color Specifies the foreground color of an element. HEX, RGB, RGBA, HSL, HSLA, color names MDN Docs
opacity Determines the transparency level of an element. Range from 0.0 (fully transparent) to 1.0 (fully opaque) MDN Docs

Common Methods to Define Colors:

Color Format Description Example
Color Names Human-friendly names for colors. red, blue, goldenrod
RGB Specifies colors using Red, Green, and Blue values. rgb(255, 0, 0) (red)
RGBA Like RGB, but with an added Alpha channel to indicate transparency. rgba(255, 0, 0, 0.5) (semi-transparent red)
HEX Uses hexadecimal values to define colors. #ff0000 (red)
HSL Represents colors using Hue, Saturation, and Lightness. Useful for creating color variations. hsl(0, 100%, 50%) (red)
HSLA Combines HSL with an Alpha channel for transparency control. hsla(0, 100%, 50%, 0.5) (semi-transparent red)

HTML:

<div id="container">
This is a paragraph.
This is another paragraph.
</div>

CSS:

#container {
  background-color: rgb(0, 25, 21);
  opacity: 0.5;
}

#container p {
  color: rgb(233, 218, 218);
}

The background color of the container is set to a dark greenish color in the example above, but it will appear lighter since the opacity is set to 50%. The font color is set to a light grayish color to provide contrast against the background.

Additional explanations:

Background

Backgrounds serve as a foundation for web elements. Whether it's a vivid color, a subtle gradient, or an evocative image, the background can enhance or soften content, guiding users' attention and enriching the visual experience.

Property Description Values MDN Documentation
background-color Defines the solid background color of an element. Any valid color value (HEX, RGB, HSL, color names) MDN Docs
background-image Sets an image or gradient as the element's background. none, url(path_to_image) MDN Docs
background-position Specifies the starting position of the background image. top left, center center, 10px 20px MDN Docs
background-repeat Determines if/how the background image will repeat. repeat, repeat-x, repeat-y, no-repeat MDN Docs
background-attachment Specifies if the background image scrolls with content or remains fixed. scroll, fixed, local MDN Docs
background-size Indicates the size of the background images. cover, contain, 50% 50% MDN Docs

Let's take a look at the following example:

<div>
This is a paragraph.
This is another paragraph.
</div>

div {
  background-color: #006400;
}

p {
  background-color: #f0f0f0;
}

In the example above, the background color of the div is set to dark green, and the background color of the paragraphs is set to light gray.

CSS offers impressive flexibility with backgrounds. Beyond mere solid colors:

Positioning

Positioning elements on a web page is a fundamental task in web design. CSS provides multiple methods to achieve desired layouts and presentations.

Core Positioning Properties:

Property Description Values MDN Documentation
position Determines the positioning method used for an element. static, relative, absolute, fixed, sticky MDN Docs
float Specifies how an element should float. none, left, right MDN Docs
clear Sets which sides of an element will not be adjacent to floating elements. none, left, right, both MDN Docs
display Dictates the display box type of an element. inline, block, inline-block, table, table-row, table-cell, none MDN Docs
visibility Defines if an element is visible. visible, hidden, collapse MDN Docs
overflow Controls what happens to content that overflows its box. visible, hidden, scroll, auto MDN Docs

HTML:

<div class="parent">
I'm the parent.
<div class="child" id="first">A</div>
<div class="child" id="second">B</div>
<div class="child" id="third">C</div>
<div class="child" id="fourth">D</div>
</div>

CSS:

.parent {
  width: 50%;
  margin: 10%;
  border: 1px solid black;
}

.child {
  width: 20%;
  height: 0;
  margin: 5%;
  padding-bottom: 20%;
  border-radius: 20%;
  text-align: center;
}

#first {
  position: absolute;
  top: 10%;
  right: 0;
  background-color: #3D9970;
}

#second {
  position: relative;
  left: 10%;
  background-color: #001f3f;
}

#third {
  background-color: #85144b;
}

#fourth {
  background-color: #DDDDDD;
}

In the example above, the parent element has a narrow rectangular border. The first child element is positioned absolutely, whereas the second is positioned relatively. The other elements have default (static) positioning.

Position Property:

Position Value Description
Static The default position. Elements are ordered as they appear in the HTML document.
Relative Elements are positioned relative to their normal position but do not affect the position of adjacent elements.
Absolute Elements are positioned relative to their closest positioned ancestor. If none exists, it is relative to the initial container.
Fixed Positioned relative to the viewport, so the element stays fixed even during scrolling.
Sticky A hybrid of relative and fixed. The element behaves as relative until a given scroll point, after which it acts as fixed.

Display Property:

Display Value Description
Inline Elements are in line with adjacent elements. Respects left/right margins and padding, but not top/bottom. Width and height cannot be set.
Block Elements form a block, breaking onto a new line. They respect all margins and padding and occupy the full width by default.
Inline-block Elements are inline but can have properties like block elements, such as width and height. Useful for buttons or items in a horizontal navigation.

Lastly, always remember that with the evolving nature of CSS and web design, utilizing developer tools in browsers and referencing platforms like MDN can help keep your understanding current and your designs sharp.

Screenshot from 2022-10-11 20-46-35

Animations and Dynamic Effects

In the digital era, motion design plays a pivotal role in enhancing user experience. CSS3, the third level of Cascading Style Sheets, offers a wide variety of animation capabilities to bring life to web elements and improve user interaction.

Animations

CSS animations allow elements to transition between styles over a set duration and through specified keyframes. This means an element can smoothly shift from one style to another over a given time period.

Core Animation Properties

Property Description Values MDN Documentation
animation Shorthand to set multiple animation properties at once. animation-name, animation-duration, animation-timing-function, animation-delay, animation-iteration-count, animation-direction, animation-fill-mode, animation-play-state MDN Docs
animation-name Names the animation for reference. string (name of the keyframes) MDN Docs
animation-duration Specifies how long the animation takes for a single cycle. time (e.g., 2s, 200ms) MDN Docs
animation-timing-function Describes the pacing of the animation. linear, ease, ease-in, ease-out, ease-in-out MDN Docs
animation-delay Sets a delay before the animation starts. time MDN Docs
animation-iteration-count Dictates how many times the animation plays. number or infinite MDN Docs
animation-direction Determines the direction of the animation. normal, reverse, alternate, alternate-reverse MDN Docs
animation-fill-mode Defines what values are applied before/after the animation. none, forwards, backwards, both MDN Docs
animation-play-state Determines whether the animation is running or paused. running, paused MDN Docs

HTML:

<div id="box">
I'm the box.
</div>

CSS:

@keyframes change_background {
  0% {
	background-color: #3D9970;
  }
  50% {
	background-color: #85144b;
  }
  100% {
	background-color: #3D9970;
  }
}

#box {
  background-color: #3D9970;
  width: 100px;
  height: 100px;
  text-align: center;
  animation: change_background 3s infinite;
}

The animation changes the background color of the box from #3D9970 to #85144b and back again. It repeats every 3 seconds and runs forever.

To create CSS animations, you'll define @keyframes that set the styling for different stages or "frames" of the animation. These @keyframes can be referenced using the animation-name property.

@keyframes slideIn {
  from {
    transform: translateX(-100%);
  }
  to {
    transform: translateX(0);
  }
}

In the example above, an animation named slideIn moves an element from off the screen (-100%) to its natural position (0). Using the animation property, you can then apply this animation to an element:

element {
  animation: slideIn 2s ease-in-out;
}

This CSS rule applies the slideIn animation to the element over a 2-second duration with an ease-in-out timing function. The possibilities are vast—allowing for rich, interactive, and engaging web designs.

2D/3D Transform

In modern web design, the ability to animate and transform elements has become a staple. CSS offers a powerful suite of properties to apply 2D and 3D transformations to elements, granting designers and developers the capacity to change an element's position, size, and orientation in creative ways.

Property Description Values MDN Documentation
transform Applies a 2D or 3D transformation to an element. none, matrix, translate, translateX, translateY, scale, rotate, skew, perspective, and 3D variants such as translate3d, rotate3d, etc. MDN Docs
transform-origin Defines the point around which a transformation is applied. origin-x origin-y origin-z (e.g., 50% 50% or center center) MDN Docs
transform-style Specifies how nested elements are rendered in 3D space. flat, preserve-3d MDN Docs
perspective Determines the distance between the viewer and the z=0 plane, affecting 3D transformations. length (e.g., 1000px) MDN Docs
perspective-origin Establishes the origin for the perspective property. length or percentage (e.g., 50% 50%) MDN Docs
backface-visibility Defines whether the back face of an element is visible when turned towards the viewer. visible, hidden MDN Docs

HTML:

<div id="box">
I'm the box.
</div>

CSS:

#box {
  background-color: #3D9970;
  width: 100px;
  height: 100px;
  text-align: center;
  transform: rotate(45deg) translate(100px, 0);
}

The box element is rotated by 45 degrees first, then translated to the right by 100 pixels.

Additional Insights:

Transition

Transitions in CSS provide a way to control animation speed when changing CSS properties. Instead of having property changes take effect instantly, you can cause the changes to take place over a period of time. This makes for a smoother visual experience and can add a touch of dynamism to web designs.

Property Description Values MDN Documentation
transition Shorthand for setting multiple transition properties at once. [ transition-property, transition-duration, transition-timing-function, transition-delay ] MDN Docs
transition-property Specifies the CSS property to which the transition is applied. none, all, Specific property names (e.g., opacity, transform) MDN Docs
transition-duration Defines the duration of the transition effect. time (e.g., 0.5s, 300ms) MDN Docs
transition-timing-function Describes how intermediate values are calculated during a transition. linear, ease, ease-in, ease-out, ease-in-out, cubic-bezier values MDN Docs
transition-delay Specifies a delay before the transition starts. time (e.g., 0.2s) MDN Docs

HTML:

<div id="box">
I'm the box.
</div>

CSS:

#box {
  background-color: #3D9970;
  width: 100px;
  height: 100px;
  text-align: center;
  transition: width 5s, height 5s, background-color 10s;
}

#box:hover {
  width: 200px;
  height: 200px;
  background-color: #FF4136;
}

Additional Insights:

Responsive Design

Responsive design ensures that websites adapt and render optimally across a variety of devices. It aims to offer a consistent user experience from the smallest mobile device to the largest desktop monitor.

Responsive Grid vs. Fluid Grid

Recommended Number of Columns:

Device Type Number of Columns
Desktop 12 columns
Tablet 8 columns
Mobile 4 columns

Mobile First Design

Adopting a Mobile First design strategy means building the initial design for the smallest screens (mobile devices) and then progressively enhancing the design for larger screens. This methodology ensures that mobile users receive only the essential features and content, helping improve performance and user experience on slower networks.

Media Queries

Media queries are the backbone of responsive design. They allow developers to apply styles based on the device characteristics. For instance, different styles can be applied depending on the device's screen width, height, orientation, and more.

Let's say we want to create a button that changes its color depending on the screen size.

HTML:

<button id="button">Click me!</button>

CSS:

#button {
  background-color: #3D9970;
  width: 100px;
  height: 100px;
  text-align: center;
}

@media screen and (max-width: 600px) {
  #button {
	background-color: #FF4136;
  }
}

Rule Description Usage Examples MDN Documentation
@media The heart of media queries in CSS. It allows for styles to be applied based on specific conditions, such as screen size or orientation. screen, print, all, min-width, max-width, orientation: portrait, orientation: landscape MDN Docs

Additional Insights:

Units

Units in CSS provide a way to express measurements. Understanding when and how to use different units is crucial for designing responsive and accessible websites.

Absolute Units

These are fixed-size units and do not scale with changes in other properties or viewer's settings.

Unit Description Conversion Example
px Pixels – A dot on the computer screen. Relative in the sense that it's not consistent across devices, but absolute within a device. Commonly used for digital screens
pt Points – Traditionally used in print media. 1pt = 1/72 of an inch. 12pt = 1/6 inch
pc Picas – A print measure where 1pc = 12 points. 1pc = 12pt
cm Centimeters. 2.54cm = 1 inch
mm Millimeters. 10mm = 1cm
in Inches – 1 inch is equal to 2.54 centimeters. 1in = 2.54cm
% Percentage – Relative to the parent element or another reference point. 50% of the parent element's size

Relative Units

Relative units are responsive and adapt based on the context in which they're used.

Unit Description Example Calculation
em Font size of the current element. If the font size is 16px, then "2em" is 32px. 2em = 32px (assuming base font size is 16px)
rem Font size of the root element (usually <html>). Consistent across nested elements. 2rem = 32px (assuming root font size is 16px)
ch Width of the '0' character of the current font. Depends on the font being used
ex x-height of the current font, roughly the height of lowercase letters in most fonts. Depends on the font being used
vh 1% of the height of the viewport window. 50vh = half of the viewport height
vw 1% of the width of the viewport window. 50vw = half of the viewport width
vmin 1% of the viewport's smaller dimension (height or width). 10vmin = 10% of the smaller viewport dimension
vmax 1% of the viewport's larger dimension (height or width). 10vmax = 10% of the larger viewport dimension

Further Insights:

Best Practices

General

Formatting

Layout and Positioning

Selectors and Specificity

Inheritance and Efficiency

Responsiveness and Accessibility

Performance and Optimization

Table of Contents

    CSS
    1. Key Points about CSS
    2. Skills Every CSS Developer Should Have
    3. Integrating CSS with HTML
    4. Understanding Selectors
      1. Selectors and Properties
      2. Different Types of CSS Selectors
      3. Introduction to Pseudo-selectors
      4. Common Pseudo-selectors
    5. Inheritance and Specificity in CSS
      1. Specificity Hierarchy
    6. Pseudo-elements in CSS
      1. Concept
      2. Common Pseudo-elements
    7. Box Model
      1. Margins
      2. Padding
      3. Border
      4. Outline
      5. Advanced Tips
    8. Flexbox
      1. Flex Container vs. Flex Items
      2. Understanding the Axes
      3. Flexbox Properties
    9. Special Styling Elements
      1. Lists & Markers
      2. Table
      3. Text
    10. Style
      1. Font
      2. Aditional explanations
      3. Colors
      4. Background
    11. Positioning
    12. Animations and Dynamic Effects
      1. Animations
      2. 2D/3D Transform
      3. Transition
    13. Responsive Design
      1. Responsive Grid vs. Fluid Grid
      2. Mobile First Design
      3. Media Queries
    14. Units
      1. Absolute Units
      2. Relative Units
    15. Best Practices
      1. General
      2. Formatting
      3. Layout and Positioning
      4. Selectors and Specificity
      5. Inheritance and Efficiency
      6. Responsiveness and Accessibility
      7. Performance and Optimization
    16. Links