Introduction to CSS

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Questions and Answers

What role does CSS primarily play in web development?

  • Managing client-side scripting and user interactions.
  • Handling server-side logic and database interactions.
  • Defining the structure and content of web pages.
  • Modifying the visual presentation of web pages. (correct)

According to W3C standards, what aspect of HTML elements does CSS describe?

  • Behavior
  • Interactivity
  • Appearance (correct)
  • Functionality

Which of the following is NOT something you can directly control using CSS?

  • Element positioning
  • Background images
  • Website file structure (correct)
  • Font properties

Which method is generally recommended for applying CSS to a webpage for better maintainability?

<p>Using a separate text file containing only CSS code. (D)</p> Signup and view all the answers

How does using CSS contribute to improved website accessibility?

<p>By separating content from presentation, allowing for varied styling based on user needs. (B)</p> Signup and view all the answers

How does CSS contribute to faster page download speeds?

<p>By reducing the need for complex HTML structures and repetitive formatting (A)</p> Signup and view all the answers

Which component of a CSS rule specifies the HTML element(s) to which the rule applies?

<p>Selector (B)</p> Signup and view all the answers

In the CSS syntax selector { property: value; }, what does the property represent?

<p>The desired style effect to apply to the selected element. (C)</p> Signup and view all the answers

What is the purpose of the font-family property in CSS?

<p>To specify the typeface used for the selected text. (D)</p> Signup and view all the answers

What is the difference between a CSS selector and a property?

<p>A selector targets HTML elements, while a property defines the specific style to apply. (D)</p> Signup and view all the answers

What does the CSS2.1 recommendation define?

<p>A large set of property names for styling HTML elements. (A)</p> Signup and view all the answers

Which color value representation is NOT directly supported in standard CSS?

<p>CMYK (B)</p> Signup and view all the answers

If you want to define a color with partial transparency in CSS, which method should you use?

<p>RGBA (C)</p> Signup and view all the answers

Which CSS unit of length is relative to the font size of the element on which it is used?

<p>em (A)</p> Signup and view all the answers

In CSS, which unit is considered absolute rather than relative in CSS3?

<p>px (B)</p> Signup and view all the answers

Which of the following methods of adding CSS styles is considered 'inline'?

<p>Using the <code>style</code> attribute directly within an HTML element. (A)</p> Signup and view all the answers

What is the primary benefit of using external style sheets in CSS?

<p>They improve site maintainability and code reusability. (A)</p> Signup and view all the answers

In CSS, what is the purpose of a selector?

<p>To tell the browser which HTML elements to style. (D)</p> Signup and view all the answers

Which of the following is NOT considered a basic type of CSS selector?

<p>Attribute selector (A)</p> Signup and view all the answers

What does the universal element selector (*) do in CSS?

<p>It selects all elements on the page. (A)</p> Signup and view all the answers

What does a grouped selector allow you to do in CSS?

<p>Apply the same styles to multiple different HTML elements. (C)</p> Signup and view all the answers

In CSS, how do you select all HTML elements with a specific class?

<p>Using the <code>.</code> symbol followed by the class name. (C)</p> Signup and view all the answers

What is the function of an ID selector in CSS?

<p>To apply styles to a single, unique element on a page. (C)</p> Signup and view all the answers

Which symbol is used to denote an ID selector in CSS?

<h1>(A)</h1> Signup and view all the answers

What is the purpose of an attribute selector in CSS?

<p>To select elements based on the presence or value of their attributes. (D)</p> Signup and view all the answers

Which of the following CSS selectors targets an <a> element whose href attribute begins with "https"?

<p>a[href^=&quot;https&quot;] (D)</p> Signup and view all the answers

What does a pseudo-element selector allow you to style?

<p>A part of an element that is not directly definable in the HTML. (C)</p> Signup and view all the answers

Which of the following is an example of a pseudo-element selector?

<p>::first-line (A)</p> Signup and view all the answers

What distinguishes a pseudo-class selector from other types of selectors?

<p>It selects elements based on a certain state or relationship. (C)</p> Signup and view all the answers

Which pseudo-class selector is used to style a link that has already been visited?

<p>:visited (D)</p> Signup and view all the answers

What does the :nth-child() pseudo-class selector do?

<p>Selects child elements based on an algebraic expression. (B)</p> Signup and view all the answers

What is the purpose of a contextual selector in CSS?

<p>Select elements based on their relationship to other elements. (C)</p> Signup and view all the answers

What does the descendant selector do?

<p>Selects all elements that are contained within another element, regardless of how deeply nested. (A)</p> Signup and view all the answers

What is the function of the child selector (>) in CSS?

<p>To select only direct child elements. (A)</p> Signup and view all the answers

What does the adjacent sibling selector (+) target?

<p>The immediately following sibling of an element. (A)</p> Signup and view all the answers

Which selector selects all the <p> elements after an <h3> element that share the same parent?

<p>h3 ~ p (C)</p> Signup and view all the answers

In the context of CSS, what is meant by 'the cascade'?

<p>How the browser applies styles when multiple rules conflict. (B)</p> Signup and view all the answers

Which of the following is NOT a type of style sheet that contributes to the CSS cascade?

<p>Printer style sheets (A)</p> Signup and view all the answers

What is the primary purpose of 'inheritance' in CSS?

<p>To allow elements to automatically adopt certain styles from their parent elements. (B)</p> Signup and view all the answers

Which CSS properties are NOT typically inherited by default?

<p>Layout, sizing, border, background, and spacing properties (C)</p> Signup and view all the answers

How can you explicitly force a CSS property to inherit a value from its parent?

<p>By using the <code>inherit</code> keyword. (D)</p> Signup and view all the answers

What does 'specificity' refer to in CSS?

<p>How explicitly a selector targets a particular element, influencing which style is applied. (D)</p> Signup and view all the answers

Which selector has the highest specificity?

<p>ID selector. (B)</p> Signup and view all the answers

Which of the following has the highest priority in CSS specificity?

<p>Inline styles (D)</p> Signup and view all the answers

If two CSS rules have the same specificity, which rule is applied?

<p>The rule that is defined later in the style sheet. (A)</p> Signup and view all the answers

Flashcards

What is CSS?

A W3C standard for visual appearance of HTML elements using properties like font, color and layout.

CSS Purpose

The principal mechanism for modifying the visual presentation of webpages.

Benefits of CSS

Improved control over formatting and better site maintainability, accessibility, page-download speed and output flexibility.

CSS Syntax

CSS rule parts: 'selector {property: value;}'.

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CSS Selector

Specifies the HTML element(s) to style.

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CSS Property

Defines which aspect of the selected element to modify.

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CSS Value

Specifies the effect on a property.

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CSS Implementation Options

Inline, embedded (internal) and external.

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Inline styles

CSS rules applied directly within HTML elements.

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Embedded Styles

CSS rules placed in the <style> element in the of the HTML document.

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External Style Sheets

CSS rules in external .css files linked to the HTML document.

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Element Selector

Selects all instances of a given HTML element.

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Grouped Selector

A selector that groups multiple elements to apply the same styles.

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Class Selector

Selects HTML elements with a specific class attribute.

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ID Selector

Targets a specific element by its id attribute.

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Attribute Selector

Selects elements based on the presence or value of an attribute.

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Pseudo-element Selector

Selects parts of an element, not elements themselves.

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Pseudo-class Selector

Targets elements based on state or relationships.

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Contextual Selector

Allow selecting elements based on their ancestors, descendants or siblings.

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Descendant Selector

A contextual selector that selects elements contained within another element.

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Child Selector

Targets direct child elements of a specified element.

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Adjacent Sibling Selector

Selects the next sibling element of a specified element.

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General Sibling Selector

Styles all following siblings of a specified element.

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CSS Cascade

Cascading process prioritizing how conflicting styles are applied.

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Types of style sheets

Author, browser, and user-defined stylesheets.

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CSS Inheritance

Controls how properties inherit from parent elements.

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Inherited Properties

Properties that are passed down to child elements by default.

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Non-inherited properties

Properties that do not inherit automatically.

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Inherit Keyword

Keyword to force a property to inherit its value from its parent.

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CSS Specificity

How the browser determines precedence of style rules.

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Specificity Hierarchy

Inline styles are highest, followed by IDs, then classes, and finally elements.

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Calculate CSS Specificity

Start at 0, add 100 for an ID, 10 for each class, and 1 for elements.

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CSS Location

The last declared rule takes precedence when specificity is equal.

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Study Notes

Introduction to CSS

  • CSS (Cascading Style Sheets) is the primary method for web authors to change the visual presentation of web pages.
  • The W3C standard describes the appearance of HTML elements using CSS.
  • Properties like font, color, size, borders, background images, positioning, and animations can be assigned to elements.
  • CSS can be added directly to HTML elements via the style attribute
  • CSS can be added within the <head> element.
  • CSS can be added in a separate text file with a .css extension.

Benefits of CSS

  • Improved control over formatting.
  • Improved site maintainability.
  • Improved accessibility.
  • Improved page-download speed.
  • Improved output flexibility.

CSS Syntax

  • A CSS rule consists of a selector and a declaration block.
  • The selector targets the HTML element(s) to be styled.
  • The declaration block contains one or more declarations, each consisting of a property and a value.
  • selector { property: value; property2: value2; } is the general syntax for CSS rules.
  • A CSS declaration must always contain a property.
  • CSS2.1 defines over a hundred property names.
  • Each CSS declaration must contain a value for a property.
  • A value's unit is dependent upon the property.
  • Some property values come from a predefined list of keywords.
  • Some values consist of Length measurements, percentages, numbers without units, color values, and URLs.

Properties: Fonts

  • font
  • font-family
  • font-size
  • font-style
  • font-weight
  • @font-face

Properties: Text

  • letter-spacing
  • line-height
  • text-align
  • text-decoration*
  • text-indent

Properties: Colors and Background

  • background
  • background-color
  • background-image
  • background-position
  • background-repeat
  • box-shadow
  • color
  • opacity

Properties: Borders

  • border*
  • border-color
  • border-width
  • border-style
  • border-top, border-left, ...*
  • border-image*
  • border-radius

Properties: Spacing

  • padding
  • padding-bottom, padding-left, ...
  • margin
  • margin-bottom, margin-left, ...

Properties: Sizing

  • height
  • max-height
  • max-width
  • min-height
  • min-width
  • width

Properties: Layout

  • bottom, left, right, top
  • clear
  • display
  • float
  • overflow
  • position
  • visibility
  • z-index

Properties: Lists

  • list-style*
  • list-style-image
  • list-style-type

Properties: Effects

  • animation*
  • filter
  • perspective
  • transform*
  • transition*

Color Value Methods

  • Name: Use one of 17 standard color names or one of 140 standard color names in CSS3.
  • RGB: Use three different numbers between 0 and 255 for red, green, and blue values.
  • Hexadecimal: Use a six-digit hexadecimal number to describe the red, green, and blue value of the color. Each of the three RGB values is between 0 and FF.
  • RGBa: Define a partially transparent background color. The "a" represents alpha, which identifies a transparency that is a value between 0.0 (fully transparent) and 1.0 (fully opaque).
  • HSL: Specify a color using Hue Saturation and Light values. HSLA is also available.

Unit Types

  • px (Pixel): Relative in CSS2, absolute (1/96 of an inch) in CSS3.
  • em: Equal to the computed font-size value of the element. The em unit is relative to the font size of the parent when used for font sizes.
  • %: Always relative to another value, varying depending on the property.
  • ex: A rarely used relative measure that expresses size in relation to an element's x-height.
  • ch: Another rarely used relative measure; expresses size in relation to the zero ("0") character width of an element.
  • rem: Stands for root em, which is the font size of the root element, and is constant throughout the document, unlike em.
  • vw, vh: Stands for viewport width and height. Percentage values (0–100) of the browser, allowing an item to change size when resizing.
  • in: Inches (absolute).
  • cm: Centimeters (absolute).
  • mm: Millimeters (absolute).
  • pt: Points, equal to 1/72 of an inch (absolute).
  • pc: Pica, equal to 1/6 of an inch (absolute).

Location of Styles: Inline Styles

  • Inline styles are style rules placed within an HTML element via the style attribute.
  • Example: <h2 style="font-size: 24pt">Description</h2>

Location of Styles: Embedded Style Sheets

  • Also called internal styles.
  • Style rules are placed within the <style> element inside the <head> element of an HTML document.

Location of Styles: External Style Sheets

  • Style rules are placed within an external text file with the .css extension.
  • The most common method due to maintainability.
  • Changes to the external style sheet are automatically reflected in all referencing HTML documents.

Selectors

  • Selectors specify the HTML elements that will be affected by property values.
  • CSS selectors allow selection of individual or multiple HTML elements.

Basic Selector Types: Element Selectors

  • Element selectors selects all instances of a given HTML element.
  • universal element selector (*) selects all elements.
  • grouped selector selects a group of elements by separating the element names with commas.

Basic Selector Types: Class Selectors

  • Class selectors select HTML elements with a specific class attribute.
  • The form is a period (.) followed by the class name.

Basic Selector Types: ID Selectors

  • ID selectors allow targeting specific elements by their id attribute.
  • The form is a pound/hash (#) followed by the id name.

Other CSS Selectors

  • Attribute Selector
  • Pseudo-element Selector
  • Pseudo-class Selector
  • Contextual Selector

Attribute Selectors

  • Select HTML elements based on the presence or value of an attribute.

Pseudo-Element Selectors

  • Select something that does not exist explicitly as an element in the HTML document tree, but which is still a recognizable selectable object.
  • Used to select the first line or first letter of any HTML element.

Pseudo-Class Selectors

  • Targets an HTML element based on a particular state or family relationship.

Contextual Selectors

  • Also called combinators.
  • Allows selection of elements based on their ancestors, descendants, or siblings.
  • A descendant selector matches all elements within another element.

Contextual Selectors: Descendant

  • div p selects a <p> element inside a <div> element.

Contextual Selectors: Child

  • div>h2 (child selector) selects an <h2> element that is a child of a <div> element.

Contextual Selectors: Adjacent Sibling

  • h3+p selects the first <p> element immediately after any <h3> element.

Contextual Selectors: General Sibling

  • h3~p: Selects all <p> elements after an <h3> element that share the same parent.

The Cascade

  • Refers to how conflicting rules are handled in CSS.

Style Sheet Types

  • Author-created style sheets.
  • User style sheets allows a user to customize page displays using a browser's accessibility options.
  • Browser style sheets defines default styles, viewable in Firefox via resource://gre-resources/forms.css.

Cascade Principles: Inheritance

  • Inheritance controls what happens when a value is unspecified for a property on an element.
  • Inherited properties are set to the computed value of the parent element by default.
  • Non-inherited properties are set to the initial value of the property by default.
  • Many CSS properties affect descendants.
  • Font, color, list, and text properties are inheritable.
  • Layout, sizing, border, background, and spacing properties are not inheritable.

Cascade Principles: Overriding Inheritance

  • The inherit keyword can force a property to inherit from its parent.

Cascade Principles: Specificity

  • Specificity determines precedence among conflicting style rules.
  • More specific selectors take precedence in CSS.

Specificity Hierarchy

  • Inline styles (highest).
  • IDs.
  • Classes, pseudo-classes, attribute selectors.
  • Elements and pseudo-elements (lowest).

Calculating Specificity

  • Start at 0.
  • Add 100 for each ID value.
  • Add 10 for each class value (or pseudo-class, or attribute selector).
  • Add 1 for each element selector or pseudo-element.

Cascade Principles: Location

  • When inheritance and specificity are equal, location determines precedence.
  • With equal specificity, the latest rule is given more weight.
  • Inline styles override external or embedded style sheets.
  • The last style property defined in a declaration block takes precedence when defined multiple times.

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