Enhancing Web Applications with Customizable Themes
User experience plays a significant role in how people interact with applications, and personalization has become a key feature for modern web platforms. One of the most requested features in web development is dark mode, which reduces eye strain, saves battery life on OLED screens, and simply looks stylish. Alongside dark mode, allowing users to switch between multiple themes enhances accessibility and usability.
Many developers assume implementing theme switching requires complex front-end frameworks, but it can be done efficiently using PHP, CSS, and JavaScript. By storing user preferences in cookies, sessions, or databases, applications can remember and apply the selected theme even after a page refresh.
Why Theme Switching Matters
People spend hours on screens, and bright interfaces can be overwhelming. Dark mode has gained popularity because it provides a comfortable viewing experience, especially in low-light environments. Many major platforms, including social media sites and operating systems, now support dark mode.
Beyond aesthetics, theme switching serves accessibility purposes. Some users may prefer a high-contrast mode, a sepia-tone display for reading, or color schemes that accommodate vision impairments. By giving users control over the look and feel of an application, developers create a more inclusive experience.
Setting Up the Basics
A theme switcher works by dynamically applying different stylesheets or CSS classes based on user selection. This requires:
- A way to store the chosen theme (cookies, sessions, or a database).
- A method to apply the selected theme when the page loads.
- A simple interface (a toggle or dropdown) for users to switch themes.
Let’s start with a basic example.
Creating the Theme Stylesheets
We need at least two stylesheets: one for light mode and another for dark mode.
css
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/* light-theme.css */
body {
background-color: #ffffff;
color: #000000;
}
/* dark-theme.css */
body {
background-color: #1a1a1a;
color: #ffffff;
}
These files define the core look of each mode.
PHP: Storing and Retrieving User Preferences
To remember a user’s theme choice, we can use cookies or sessions. Cookies are useful for persistent storage, whereas sessions work well for temporary changes that reset after closing the browser.
Here’s a PHP snippet that sets a theme choice using cookies:
php
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if (isset($_POST[‘theme’])) {
$theme = $_POST[‘theme’];
setcookie(‘theme’, $theme, time() + (86400 * 30), “/”); // Store for 30 days
}
This code saves the user’s selection in a cookie for one month.
When the page loads, the theme should be retrieved and applied:
php
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$theme = isset($_COOKIE[‘theme’]) ? $_COOKIE[‘theme’] : ‘light’;
$stylesheet = ($theme === ‘dark’) ? ‘dark-theme.css’ : ‘light-theme.css’;
?>
<link rel=”stylesheet” href=”<?php echo $stylesheet; ?>”>
This ensures the correct stylesheet is applied based on the saved preference.
Adding a Theme Switcher
Next, let’s create a simple theme toggle that submits the selected mode.
html
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<form method=”post”>
<select name=”theme” onchange=”this.form.submit()”>
<option value=”light” <?php if ($theme === ‘light’) echo ‘selected’; ?>>Light Mode</option>
<option value=”dark” <?php if ($theme === ‘dark’) echo ‘selected’; ?>>Dark Mode</option>
</select>
</form>
When the user selects a theme, the form submits automatically, triggering the PHP script to update the cookie.
Improving the Experience with JavaScript
Reloading the page every time a theme changes isn’t ideal. JavaScript can make the switch instantaneous:
js
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document.addEventListener(“DOMContentLoaded”, function() {
const themeSelector = document.querySelector(“select[name=’theme’]”);
themeSelector.addEventListener(“change”, function() {
document.body.className = this.value;
document.cookie = “theme=” + this.value + “; path=/; max-age=” + (30 * 24 * 60 * 60);
});
});
With this script, the theme changes without reloading, and the preference is still stored in a cookie.
Using Sessions Instead of Cookies
If theme switching should reset after the user leaves the site, sessions are a good alternative:
php
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session_start();
if (isset($_POST[‘theme’])) {
$_SESSION[‘theme’] = $_POST[‘theme’];
}
$theme = isset($_SESSION[‘theme’]) ? $_SESSION[‘theme’] : ‘light’;
$stylesheet = ($theme === ‘dark’) ? ‘dark-theme.css’ : ‘light-theme.css’;
?>
<link rel=”stylesheet” href=”<?php echo $stylesheet; ?>”>
Sessions keep changes only during the browsing session, clearing preferences when the browser is closed.
Storing Preferences in a Database
For user accounts, storing preferences in a database is the best approach. Instead of using cookies or sessions, save the theme selection in a users table.
Database schema example:
sql
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ALTER TABLE users ADD COLUMN theme VARCHAR(10) DEFAULT ‘light’;
To update the preference:
php
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$user_id = $_SESSION[‘user_id’];
$theme = $_POST[‘theme’];
$query = “UPDATE users SET theme = ? WHERE id = ?”;
$stmt = $pdo->prepare($query);
$stmt->execute([$theme, $user_id]);
When a user logs in, fetch and apply the saved theme:
php
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$query = “SELECT theme FROM users WHERE id = ?”;
$stmt = $pdo->prepare($query);
$stmt->execute([$user_id]);
$theme = $stmt->fetchColumn() ?: ‘light’;
Expanding Beyond Dark Mode
Theme switching isn’t limited to dark and light mode. You can create multiple themes, such as high contrast for accessibility or pastel tones for a soft aesthetic.
For instance, expanding the select dropdown:
html
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<select name=”theme” onchange=”this.form.submit()”>
<option value=”light” <?php if ($theme === ‘light’) echo ‘selected’; ?>>Light Mode</option>
<option value=”dark” <?php if ($theme === ‘dark’) echo ‘selected’; ?>>Dark Mode</option>
<option value=”pastel” <?php if ($theme === ‘pastel’) echo ‘selected’; ?>>Pastel Mode</option>
<option value=”high-contrast” <?php if ($theme === ‘high-contrast’) echo ‘selected’; ?>>High Contrast</option>
</select>
Each theme would have its own CSS file, and the PHP logic remains the same.
Making Your PHP Application More User-Friendly
Integrating dark mode and theme switching into a PHP application improves usability and gives users more control over their browsing experience. A well-designed theme switcher allows visitors to select a style that suits their environment, reducing eye strain and making navigation more comfortable. With just a few lines of PHP, CSS, and JavaScript, these features can be implemented seamlessly while ensuring that user preferences are remembered across sessions.
Beyond enhancing accessibility, theme customization also adds a layer of personalization that can increase user engagement. Visitors are more likely to spend time on a website that adapts to their visual comfort. Whether using cookies, sessions, or database storage, offering multiple themes makes an application feel more modern, accommodating, and visually appealing.
As technology continues to prioritize user-centric design, small yet impactful features like theme switching can set an application apart. By giving users the freedom to tailor their experience, developers create a more welcoming and adaptable interface—one that meets the diverse needs of an ever-growing audience.
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