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CSS Pseudo-Classes, Pseudo-Elements, and Media Queries

 18min
AI-enhanced Web3 Frontend Development Course CSS Pseudo-Classes, Pseudo-Elements, and Media Queries

Introduction:

Embrace the power of CSS to elevate the user experience with pseudo-classes, pseudo-elements, and media queries.

In this lesson, we dive into the dynamic world of CSS to enhance the aesthetics and responsiveness of Web3 applications.

Remember, watching the lesson video will offer a deeper understanding of this topic.

Learning Objectives:

By the end of this lesson, you will be able to:

  1. Understand the purpose and usage of pseudo-classes and pseudo-elements in CSS.
  2. Learn to create responsive designs with media queries.
  3. Apply these advanced styling techniques to the Token Minter dApp, enhancing its interactivity and responsiveness.

Lesson Video:

What Is Pseudo-Classes and Pseudo-Elements?

Pseudo-classes allow you to define a special state of an element, such as :hover, :focus, or :active.

Pseudo-elements, on the other hand, enable you to style certain parts of an element, like ::before and ::after.

What Is Media Queries?

Media queries are crucial for building responsive designs.

They enable the application of different styles for different devices or screen sizes, ensuring that your dApp looks great on all devices.

Implementing Media Queries, Pseudo-Classes and Pseudo-Elements:

Let’s take our Token Minter dApp to the next level by incorporating these advanced CSS features.

Example Codes for Practical Application:

Expanding the Capstone Project

Expanding on our Token Minter dApp, let’s enhance its features using what you learned from this lesson.

Existing Capstone Project Code from Previous Lesson:

CSS Code:

/* External CSS */

/* IMPORTS */

/* Importing a custom Google font */
@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;700&display=swap');



/* BODY */

/* Basic styling for the body */
body {
    font-family: 'Roboto', sans-serif; /* Applying the imported font family to the body */
    background-color: #f4f4f4;
    background: linear-gradient(to right, #630404, #e040fb, #6a027c); /* Darker brown to lighter purple gradient background */
}


/* NAVIGATION */

/* Styling navigation menu using child combinator */
nav > ul > li {
    display: inline;
    margin-right: 20px;
    text-align: center; /* Aligns text to the center */
    /* Flex item styling for responsive nav items */
    padding: 10px;
    flex: 1; /* Allows each item to grow */
}

/* Styling the navigation menu with a hover effect */
nav a:hover {
    background-color: #630404; /* Light background on hover */
    color: #f3e40d; /* Dark text on hover */
}



/* HYPERLINKS */

/* Styling links using attribute selector */
a[href^="#"] {
    text-decoration: none;
    color: white;
}



/* HEADINGS */

/* Styling for the header using element selector */
header {
    background: #333; 
    color: white; 
    padding: 10px;
    text-align: center;
    /* Flex container for the header to space out elements */
    display: flex;
    justify-content: space-between; /* Distributes space between items */
    align-items: center; /* Aligns items vertically */
    padding: 0 10px;
}

/* Styling headings for emphasis */
h1, h2, h3 {
    font-weight: 700; /* Makes the font bold */
}

/* Styling paragraph using adjacent sibling combinator */
h2 + p {
    color: #cfbdbd;
}      



/* MAIN */

/* Styling for the main content area */
/* main {
    margin: 20px;
    border: 2px solid #333;
    padding: 10px;
    display: grid;
    grid-template-columns: 2fr 3fr; One column for the aside, three for the main content 
    gap: 20px; Space between grid items 
} */

/* Flex container for main content area */
main {
    display: flex;
    flex-direction: row; /* Stacks items vertically */
    gap: 10px; /* Creates space between flex items */
}

/* ARTICLE */

/* Styling for the article */
article {
    margin-bottom: 15px;
    padding: 10px;
    border: 1px solid grey;
    /* Flex item adjustments for articles within main */
    flex: 1; /* Allows the article to grow and fill the space */
}
/* Applying Box Model to the paragraph */
article p {
    margin-bottom: 20px;
    border: 1px solid grey;
    padding: 15px;
}



/* IDs */

/* Targeting specific section with ID selector */
#mint {
    background-color: #eaeaea;
    padding: 15px;
    margin-top: 10px;
}

/* Styling for the form inside the mint section */
#mint form {
    padding: 10px;
    border: 1px solid #ddd;
    margin-top: 10px;
}

/* Flex container for the form inside mint section */
#mint form {
    display: flex;
    flex-direction: column; /* Stacks form items vertically */
    gap: 10px; /* Creates space between form items */
}

/* Styling for input and button elements */
#mint input,
#mint button {
    padding: 10px;
    margin-bottom: 10px;
    border: 1px solid #ccc;
    flex: 1; /* Allows inputs and button to grow */
}



/* PARAGRAPH */

/* Adjusting paragraph line spacing for readability */
p {
    line-height: 3.5; /* Sets the space between lines */
}

HTML Code:

<!DOCTYPE html> <!-- Defines document type and HTML version -->
<html lang="en"> <!-- Sets the language of the page -->

<head>
    <meta charset="UTF-8"> <!-- Sets character encoding for the document -->
    <meta name="viewport" content="width=device-width, initial-scale=1.0"> <!-- Ensures proper rendering on mobile devices -->
    <title>Token Minter dApp</title> <!-- Title of the webpage -->
    <link rel="stylesheet" href="/globalstyles.css"> <!-- Link to external CSS file -->
</head>

<body>
    <header>
        <!-- Site header with navigation -->
        <h1>Token Minter dApp</h1>
        <nav>
            <!-- Navigation links -->
            <ul>
                <li><a href="#home">Home</a></li>
                <li><a href="#mint">Mint Tokens</a></li>
                <li><a href="#about">About</a></li>
            </ul>
        </nav>
    </header>
    
    <main>
        <!-- Main content section -->
        <article id="home">
            <!-- Introduction article -->
            <h2>Introduction to Token Minting</h2>
            <p>This dApp allows users to mint their own tokens on the blockchain.</p>
        </article>
        
        <section id="mint">
            <!-- Token minting form section -->
            <h2>Mint Your Tokens</h2>
            <form action="#">
                <!-- Form for token minting -->
                <input type="email" placeholder="Enter your email">
                <input type="number" placeholder="Token amount">
                <button type="submit">Mint</button>
            </form>
        </section>
        
        <aside>
            <!-- Sidebar with additional information -->
            <h3>Learn More:</h3>
            <p>Explore more about blockchain technology.</p>
        </aside>
    </main>
    
    <footer>
        <!-- Footer with contact information -->
        <p>Contact us at <a href="mailto:hello@dProgrammingUniversity.com">hello@dProgrammingUniversity.com</a></p>
    </footer>
    
</body>
</html>

Enhance the Capstone Project with New Features from this Lesson:

CSS Code:

/* External CSS File: styles.css */

/* Pseudo-classes for interactive navigation links */
nav a:hover, nav a:focus {
    background-color: #444; /* Darkens the background on hover/focus */
    color: #fff; /* Ensures the text is visible on a dark background */
}

/* Pseudo-element for the subtitle */
h1::after {
    content: '...the future of token minting'; /* This is the subtitle */
    display: block;
    text-align: center;
    color: #aaa; /* Lighter text color for the subheading */
    position: absolute; /* Position the subtitle absolutely */
    width: 100%; /* Let the subtitle span the entire width of the h1 */
    left: 0; /* Align left edge with the h1 */
    top: 100%; /* Position it just below the h1 */
    font-size: 0.55em; /* Adjust the font size as needed */
}

/* Media query for tablet devices */
@media (min-width: 768px) and (max-width: 1024px) {
    body {
        background: linear-gradient(to right, #6a027c, #630404); /* Adjust the gradient for medium screens */
    }

    main {
        flex-direction: row; /* Aligns main content and aside side by side */
    }
}

/* Media query for mobile devices */
@media (max-width: 767px) {
    nav ul {
        flex-direction: column; /* Stacks nav items vertically */
    }

    .button {
        padding: 15px; /* Larger padding for touch targets */
    }
}

AFTER:

Your code may look something like the following after applying the above adjustment from this lesson:

CSS Code:

/* External CSS */

/* IMPORTS */

/* Importing a custom Google font */
@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;700&display=swap');



/* BODY */

/* Basic styling for the body */
body {
    font-family: 'Roboto', sans-serif; /* Applying the imported font family to the body */
    background-color: #f4f4f4;
    background: linear-gradient(to right, #630404, #e040fb, #6a027c); /* Darker brown to lighter purple gradient background */
}


/* NAVIGATION */

/* Styling navigation menu using child combinator */
nav > ul > li {
    display: inline;
    margin-right: 20px;
    text-align: center; /* Aligns text to the center */
    /* Flex item styling for responsive nav items */
    padding: 10px;
    flex: 1; /* Allows each item to grow */
}

/* Pseudo-classes for interactive navigation links: Styling the navigation menu with a hover effect */
nav a:hover, nav a:focus {
    background-color: #630404; /* Light background on hover */
    color: #f3e40d; /* Dark text on hover */
}



/* HYPERLINKS */

/* Styling links using attribute selector */
a[href^="#"] {
    text-decoration: none;
    color: white;
}



/* HEADINGS */

/* Styling for the header using element selector */
header {
    background: #333; 
    color: white; 
    padding: 10px;
    text-align: center;
    /* Flex container for the header to space out elements */
    display: flex;
    justify-content: space-between; /* Distributes space between items */
    align-items: center; /* Aligns items vertically */
    padding: 0 10px;
}

/* Styling headings for emphasis */
h1 {
    font-weight: 700; /* Makes the font bold */
    position: relative; /* This will allow absolute positioning of the pseudo-element relative to the h1 */
}

/* Pseudo-element for the subtitle */
h1::after {
    content: '...the future of token minting'; /* This is the subtitle */
    display: block;
    text-align: center;
    color: #aaa; /* Lighter text color for the subheading */
    position: absolute; /* Position the subtitle absolutely */
    width: 100%; /* Let the subtitle span the entire width of the h1 */
    left: 0; /* Align left edge with the h1 */
    top: 100%; /* Position it just below the h1 */
    font-size: 0.55em; /* Adjust the font size as needed */
}

/* Styling headings for emphasis */
h1, h2, h3 {
    font-weight: 700; /* Makes the font bold */
}

/* Styling paragraph using adjacent sibling combinator */
h2 + p {
    color: #cfbdbd;
}      



/* MAIN */

/* Styling for the main content area */
/* main {
    margin: 20px;
    border: 2px solid #333;
    padding: 10px;
    display: grid;
    grid-template-columns: 2fr 3fr; One column for the aside, three for the main content 
    gap: 20px; Space between grid items 
} */

/* Flex container for main content area */
main {
    display: flex;
    flex-direction: row; /* Stacks items vertically */
    gap: 10px; /* Creates space between flex items */
}

/* ARTICLE */

/* Styling for the article */
article {
    margin-bottom: 15px;
    padding: 10px;
    border: 1px solid grey;
    /* Flex item adjustments for articles within main */
    flex: 1; /* Allows the article to grow and fill the space */
}
/* Applying Box Model to the paragraph */
article p {
    margin-bottom: 20px;
    border: 1px solid grey;
    padding: 15px;
}



/* IDs */

/* Targeting specific section with ID selector */
#mint {
    background-color: #eaeaea;
    padding: 15px;
    margin-top: 10px;
}

/* Styling for the form inside the mint section */
#mint form {
    padding: 10px;
    border: 1px solid #ddd;
    margin-top: 10px;
}

/* Flex container for the form inside mint section */
#mint form {
    display: flex;
    flex-direction: column; /* Stacks form items vertically */
    gap: 10px; /* Creates space between form items */
}

/* Styling for input and button elements */
#mint input,
#mint button {
    padding: 10px;
    margin-bottom: 10px;
    border: 1px solid #ccc;
    flex: 1; /* Allows inputs and button to grow */
}



/* PARAGRAPH */

/* Adjusting paragraph line spacing for readability */
p {
    line-height: 3.5; /* Sets the space between lines */
}



/* MEDIA QUERY */

/* Media query for tablet devices */
@media (min-width: 768px) and (max-width: 1024px) {
    body {
        background: linear-gradient(to right, #6a027c, #630404); /* Adjust the gradient for medium screens */
    }

    main {
        flex-direction: row; /* Aligns main content and aside side by side */
    }
}

/* Media query for mobile devices */
@media (max-width: 767px) {
    nav ul {
        flex-direction: column; /* Stacks nav items vertically */
    }

    .button {
        padding: 15px; /* Larger padding for touch targets */
    }
}

HTML Code:

<!DOCTYPE html> <!-- Defines document type and HTML version -->
<html lang="en"> <!-- Sets the language of the page -->

<head>
    <meta charset="UTF-8"> <!-- Sets character encoding for the document -->
    <meta name="viewport" content="width=device-width, initial-scale=1.0"> <!-- Ensures proper rendering on mobile devices -->
    <title>Token Minter dApp</title> <!-- Title of the webpage -->
    <link rel="stylesheet" href="/globalstyles.css"> <!-- Link to external CSS file -->
</head>

<body>
    <header>
        <!-- Site header with navigation -->
        <h1>Token Minter dApp</h1>
        <nav>
            <!-- Navigation links -->
            <ul>
                <li><a href="#home">Home</a></li>
                <li><a href="#mint">Mint Tokens</a></li>
                <li><a href="#about">About</a></li>
            </ul>
        </nav>
    </header>
    
    <main>
        <!-- Main content section -->
        <article id="home">
            <!-- Introduction article -->
            <h2>Introduction to Token Minting</h2>
            <p>This dApp allows users to mint their own tokens on the blockchain.</p>
        </article>
        
        <section id="mint">
            <!-- Token minting form section -->
            <h2>Mint Your Tokens</h2>
            <form action="#">
                <!-- Form for token minting -->
                <input type="email" placeholder="Enter your email">
                <input type="number" placeholder="Token amount">
                <button class="button" type="submit">Mint</button>
            </form>
        </section>
        
        <aside>
            <!-- Sidebar with additional information -->
            <h3>Learn More:</h3>
            <p>Explore more about blockchain technology.</p>
        </aside>
    </main>
    
    <footer>
        <!-- Footer with contact information -->
        <p>Contact us at <a href="mailto:hello@dProgrammingUniversity.com">hello@dProgrammingUniversity.com</a></p>
    </footer>
    
</body>
</html>

Conclusion:

Through this lesson, you’ve unlocked new possibilities for styling and responsiveness with pseudo-classes, pseudo-elements, and media queries.

These tools will empower you to create a dApp that not only functions well but also provides a seamless and accessible user experience across all devices.

Resources & References:

To deepen your understanding of this lesson, you can explore the following resources:

  1. MDN Web Docs – CSS Pseudo-class/elements reference
  2. W3Schools – CSS Flexbox Tutorial
  3. MDN Web Docs – CSS Media Query reference

These resources provide comprehensive guides and examples that will be invaluable as you learn and apply them in your journey of Web3 frontend development.

Support:

If you need help with this lesson, questions, suggestions and improvement. The best way to get help is to use the comment below:
1. First check existing comments if your questions have been answered before posting.
2. If no existing related question with an answer, then you can post a new one (kindly avoid duplicating previously asked and answered questions).

NOTE: This is the most recommended way of getting support directly from the instructor of this course. Posting on other platforms like Discord may get support from other community members and not from the course instructor directly.

Images|Videos|Links: To support your question with a screenshot, Github repo link or other media, kindly upload it somewhere online like Drive/Dropbox or Github (for codes) first, then post the link to it in your comment. Please do not upload media/codes directly, it may fail or cause your comment to be deleted.

Please ONLY post questions that are specific to this lesson not the entire course to ensure others can find it helpful. Each lesson allows comments relating to it ONLY. Off-lesson questions will be deleted even if they relate to this course as a whole but as long as they are not specific to this lesson, they are not allowed.

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