CSS: selectors and properties

Lecture 2: Selectors and Properties

In this lecture, we'll dive into the building blocks of CSS: selectors and properties. These are essential concepts that allow you to target specific elements on your webpage and style them effectively.

---

What are CSS Selectors?

CSS selectors are patterns used to select the HTML elements you want to style. Different types of selectors allow you to apply styles to various elements based on their tag, class, ID, attributes, and more.

Types of Selectors

1. Element (Type) Selector:

   • Targets all elements of a specific type.
   • Example:

    p {
      color: green;
    }
   

   This will change the color of all e388a4556c0f65e1904146cc1a846bee elements to green.

2. Class Selector:

   • Targets elements with a specific class attribute.
   • Example:

    .highlight {
      background-color: yellow;
    }
   

   In your HTML, any element with class="highlight" will have a yellow background.
   

    <p class="highlight">This is highlighted text.</p>
   

3. ID Selector:

   • Targets a single element with a unique ID attribute.
   • Example:

    #header {
      font-size: 24px;
    }
   

   Only the element with id="header" will have a font size of 24px.
   

    <div id="header">Welcome to My Website</div>
   

4. Group Selector:

   • Applies the same style to multiple selectors.
   • Example:

    h1, h2, h3 {
      color: blue;
    }
   

   This rule will make all 4a249f0d628e2318394fd9b75b4636b1, c1a436a314ed609750bd7c7d319db4da, and 684271ed9684bde649abda8831d4d355 elements blue.

5. Descendant Selector:

   • Targets elements that are inside (descendants of) other elements.
   • Example:

    div p {
      font-style: italic;
    }
   

   This will make all e388a4556c0f65e1904146cc1a846bee elements inside a dc6dce4a544fdca2df29d5ac0ea9906b italicized.
   

    <div>
      <p>This text is italicized because it's inside a div.</p>
    </div>
   

Understanding CSS Properties

CSS properties define what aspects of the selected elements you want to style. Each property is followed by a value that specifies the desired outcome.

Example Properties:

• Color:

  • Sets the text color.
  • Example:

  h1 {
    color: red;
  }
  

• Background-Color:

  • Sets the background color.
  • Example:

  body {
    background-color: #f0f0f0;
  }
  

• Font-Size:

  • Sets the size of the text.
  • Example:

  p {
    font-size: 16px;
  }
  

• Margin:

  • Sets the space outside an element.
  • Example:

  .box {
    margin: 20px;
  }
  

• Padding:

  • Sets the space inside an element, between the content and the border.
  • Example:

  .content {
    padding: 10px;
  }
  

Practical Examples:

Let’s combine what we’ve learned with a simple example.

HTML:

8ca2b4eb17525146e680c309e9dfa6a5
  4a249f0d628e2318394fd9b75b4636b1Welcome to CSS Basics473f0a7621bec819994bb5020d29372a
  03c914392195facb4bb03ef129401e65This is an introduction to CSS selectors and properties.94b3e26ee717c64999d7867364b1b4a3
  e388a4556c0f65e1904146cc1a846beeSelectors help you target elements, and properties allow you to style them.94b3e26ee717c64999d7867364b1b4a3
16b28748ea4df4d9c2150843fecfba68

CSS:

/* ID Selector */
#container {
  border: 2px solid black;
  padding: 10px;
}

/* Element Selector */
h1 {
  color: purple;
}

/* Class Selector */
.intro {
  background-color: lightblue;
  font-size: 18px;
}

/* Group Selector */
h1, p {
  font-family: Arial, sans-serif;
}

/* Descendant Selector */
#container p {
  margin-bottom: 15px;
}

In this example:

• The #container div is styled with a black border and padding.
• The 4a249f0d628e2318394fd9b75b4636b1 heading is colored purple.
• The paragraph with the class intro has a light blue background and a larger font size.
• Both 4a249f0d628e2318394fd9b75b4636b1 and e388a4556c0f65e1904146cc1a846bee elements use the Arial font.
• All paragraphs inside #container have a bottom margin for spacing.

Practice Exercise

1. Create a simple HTML file with headings, paragraphs, and divs.
2. Experiment with different selectors and properties to style your content.
3. Try using the descendant selector to style nested elements.
4. Play with the grouping selector to apply the same styles to multiple elements.

---

Next Up: In the next lecture, we'll explore the CSS Box Model and learn how margins, borders, padding, and content come together to define the layout of your web elements. See you there!

Follow me on -

LinkedIn- Ridoy Hasan

-

The above is the detailed content of CSS: selectors and properties. For more information, please follow other related articles on the PHP Chinese website!