CSS Basic Coding | Learn CSS Basic

CSS (Cascading Style Sheets) is a stylesheet language used to describe the presentation of a document written in HTML. It allows you to control the layout, colors, fonts, and overall visual style of a web page. Here’s a basic introduction to CSS coding and some of the fundamental properties used to style HTML elements.

Basic Structure of a CSS File

CSS can be included in an HTML document in three ways: inline, internal, and external.

1. Inline CSS

Inline CSS is used to apply a unique style to a single HTML element. It uses the style attribute within the element’s tag.

<p style="color: blue; text-align: center;">This is a blue, centered paragraph.</p>

2. Internal CSS

Internal CSS is used to define styles for a single HTML document. The styles are defined within a <style> element in the <head> section.

<!DOCTYPE html>
<html>
<head>
    <style>
        body {
            background-color: lightgray;
        }
        h1 {
            color: blue;
            text-align: center;
        }
        p {
            font-family: Arial, sans-serif;
            font-size: 14px;
        }
    </style>
</head>
<body>
    <h1>This is a heading</h1>
    <p>This is a paragraph.</p>
</body>
</html>

3. External CSS

External CSS is used to define styles for multiple HTML pages. The styles are defined in an external .css file and linked to the HTML document using the <link> element.

style.css

body {
    background-color: lightgray;
}
h1 {
    color: blue;
    text-align: center;
}
p {
    font-family: Arial, sans-serif;
    font-size: 14px;
}

index.html

<!DOCTYPE html>
<html>
<head>
    <link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
    <h1>This is a heading</h1>
    <p>This is a paragraph.</p>
</body>
</html>

Basic CSS Syntax

A CSS rule consists of a selector and a declaration block:

selector {
    property: value;
    property: value;
}
  • Selector: Specifies the HTML element you want to style.
  • Property: The aspect of the element you want to change (e.g., color, font-size).
  • Value: The value you want to apply to the property (e.g., blue, 14px).

Common CSS Selectors

  • Element Selector: Targets all instances of a given HTML element.
  p {
      color: red;
  }
  • ID Selector: Targets a single element with a specific id attribute. Prefixed with #.
  #header {
      background-color: yellow;
  }
  • Class Selector: Targets elements with a specific class attribute. Prefixed with ..
  .highlight {
      background-color: yellow;
  }
  • Universal Selector: Targets all elements.
  * {
      margin: 0;
      padding: 0;
  }
  • Attribute Selector: Targets elements with a specific attribute.
  [type="text"] {
      border: 1px solid black;
  }

Common CSS Properties

  • Color and Background
  color: blue;
  background-color: lightgray;
  • Font
  font-family: Arial, sans-serif;
  font-size: 16px;
  font-weight: bold;
  • Text
  text-align: center;
  text-decoration: underline;
  • Box Model (Spacing)
  margin: 20px;
  padding: 10px;
  border: 1px solid black;
  • Dimensions
  width: 100px;
  height: 200px;
  • Display and Positioning
  display: block;
  position: absolute;
  top: 50px;
  left: 100px;

Example of Applying CSS

Here is a simple example to demonstrate the application of various CSS properties:

style.css

body {
    background-color: lightgray;
    font-family: Arial, sans-serif;
}

h1 {
    color: blue;
    text-align: center;
    margin-top: 50px;
}

p {
    font-size: 14px;
    color: black;
    line-height: 1.6;
    margin: 20px;
}

#main-content {
    background-color: white;
    padding: 20px;
    border: 1px solid #ccc;
    width: 80%;
    margin: auto;
}

.highlight {
    background-color: yellow;
    font-weight: bold;
}

index.html

<!DOCTYPE html>
<html>
<head>
    <link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
    <h1>Welcome to My Webpage</h1>
    <div id="main-content">
        <p>This is a paragraph inside the main content area. Here is some <span class="highlight">highlighted text</span>.</p>
        <p>Another paragraph with some more content.</p>
    </div>
</body>
</html>

By using CSS, you can significantly enhance the appearance and usability of your web pages.