Bootstrap 3 Tutorial

CSS All Classes

Last modified on: October 28, 2024

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<h2 class="relative p-1 rounded-sm flex items-center justify-center bg-token-main-surface-primary text-token-text-primary h-8 w-8">CSS All Classes</h2>
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<p>CSS (Cascading Style Sheets) is a stylesheet language used for describing the presentation of a document written in HTML or XML. CSS classes are a powerful feature that allows you to apply styles to multiple elements without repeating your code. Here's a guide to understanding and utilizing CSS classes effectively.</p>
<h4>What is a CSS Class?</h4>
<p>A CSS class is defined in a stylesheet and is used to style elements in your HTML. Classes are prefixed with a dot (<code>.</code>) in the CSS file and can be applied to HTML elements using the <code>class</code> attribute.</p>
<h3>Syntax</h3>
<h4>Defining a Class</h4>
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<pre class="language-css"><code>.class-name {
    property: value;
}
</code></pre>
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<ul>
<li><strong>class-name</strong>: The name of the class, which can be any valid identifier.</li>
<li><strong>property</strong>: The CSS property you want to change (e.g., <code>color</code>, <code>font-size</code>, <code>margin</code>).</li>
<li><strong>value</strong>: The value you want to assign to that property.</li>
</ul>
<h4>Example</h4>
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<pre class="language-css"><code>.button {
    background-color: blue;
    color: white;
    padding: 10px 15px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

.alert {
    color: red;
    font-weight: bold;
}
</code></pre>
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<h3>Applying Classes in HTML</h3>
<p>You can apply classes to HTML elements using the <code>class</code> attribute:</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary">html</div>
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<pre class="language-markup"><code>&lt;button class="button"&gt;Click Me&lt;/button&gt;
&lt;p class="alert"&gt;This is an alert message!&lt;/p&gt;
</code></pre>
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<h3>Combining Multiple Classes</h3>
<p>You can also apply multiple classes to a single element by separating the class names with spaces:</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary">html</div>
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<pre class="language-markup"><code>&lt;div class="alert important"&gt;This is an important alert!&lt;/div&gt;
</code></pre>
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<h3>CSS Class Selectors</h3>
<ol>
<li>
<p><strong>Single Class Selector</strong>: Targets elements with a specific class.</p>
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<pre class="language-css"><code>.class-name {
    /* styles */
}
</code></pre>
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</li>
<li>
<p><strong>Multiple Class Selectors</strong>: Targets elements with multiple specific classes.</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary">css</div>
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<pre class="language-css"><code>.class1.class2 {
    /* styles */
}
</code></pre>
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</li>
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<p><strong>Class Hierarchy Selector</strong>: Targets an element with a specific class within another class.</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary">css</div>
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<pre class="language-css"><code>.parent-class .child-class {
    /* styles */
}
</code></pre>
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</li>
</ol>
<h3>Common CSS Classes</h3>
<p>Here's a list of commonly used CSS classes and their purposes:</p>
<table>
<thead>
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<th>Class Name</th>
<th>Description</th>
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<tbody>
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<td><code>.text-center</code></td>
<td>Center-aligns text.</td>
</tr>
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<td><code>.text-left</code></td>
<td>Left-aligns text.</td>
</tr>
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<td><code>.text-right</code></td>
<td>Right-aligns text.</td>
</tr>
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<td><code>.hidden</code></td>
<td>Hides an element.</td>
</tr>
<tr>
<td><code>.visible</code></td>
<td>Shows a hidden element.</td>
</tr>
<tr>
<td><code>.bg-primary</code></td>
<td>Applies a primary background color.</td>
</tr>
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<td><code>.bg-secondary</code></td>
<td>Applies a secondary background color.</td>
</tr>
<tr>
<td><code>.border</code></td>
<td>Adds a border to an element.</td>
</tr>
<tr>
<td><code>.rounded</code></td>
<td>Rounds the corners of an element.</td>
</tr>
<tr>
<td><code>.shadow</code></td>
<td>Adds a shadow effect to an element.</td>
</tr>
</tbody>
</table>
<h3>Best Practices</h3>
<ol>
<li>
<p><strong>Naming Conventions</strong>: Use descriptive and meaningful class names that reflect the purpose of the class (e.g., <code>.btn-primary</code>, <code>.alert-danger</code>).</p>
</li>
<li>
<p><strong>Avoid Overusing Classes</strong>: Try to use classes efficiently to minimize clutter in your HTML.</p>
</li>
<li>
<p><strong>Maintain Consistency</strong>: Follow a consistent naming pattern throughout your CSS to improve readability and maintainability.</p>
</li>
<li>
<p><strong>Use Comments</strong>: Comment your CSS code to explain complex styles or to categorize related classes.</p>
</li>
</ol>
<h3>Example Project</h3>
<p>Here's a simple example to illustrate the use of CSS classes:</p>
<h4>HTML</h4>
<div class="contain-inline-size rounded-md border-[0.5px] border-token-border-medium relative bg-token-sidebar-surface-primary dark:bg-gray-950">
<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary">html</div>
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<pre class="language-markup"><code>&lt;!DOCTYPE html&gt;
&lt;html lang="en"&gt;
&lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt;
    &lt;title&gt;CSS Classes Example&lt;/title&gt;
    &lt;link rel="stylesheet" href="styles.css"&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;h1 class="text-center"&gt;Welcome to CSS Classes&lt;/h1&gt;
    &lt;button class="button"&gt;Click Me&lt;/button&gt;
    &lt;p class="alert"&gt;This is an alert message!&lt;/p&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>
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<h4>CSS (styles.css)</h4>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary">css</div>
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<pre class="language-css"><code>body {
    font-family: Arial, sans-serif;
}

.text-center {
    text-align: center;
}

.button {
    background-color: blue;
    color: white;
    padding: 10px 15px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

.alert {
    color: red;
    font-weight: bold;
}
</code></pre>
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<h3>Conclusion</h3>
<p>CSS classes are essential for styling your web pages effectively. By understanding how to define and apply classes, you can create flexible and maintainable styles for your HTML documents. Use the best practices outlined above to enhance your CSS skills and improve your web development projects!</p>
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