Toggle theme with CSS and JavaScript

by Ali Uygur

HTML

<div class="theme-container">
  <button id="theme-toggle" class="toggle-btn">Temayı Değiştir</button>
  <div class="card">
    <h1>Modern Web Tasarımı</h1>
    <p>CSS ve JavaScript kullanarak dinamik tema geçişleri yapmak, kullanıcı deneyimini üst seviyeye çıkarır.</p>
  </div>
</div>

CSS

:root {
  --bg-color: #f4f7f6;
  --text-color: #333333;
  --card-bg: #ffffff;
  --card-shadow: rgba(0, 0, 0, 0.1);
  --btn-bg: #2ecc71;
  --btn-text: #ffffff;
}

body.dark-theme {
  --bg-color: #1e1e24;
  --text-color: #f4f7f6;
  --card-bg: #2a2a35;
  --card-shadow: rgba(0, 0, 0, 0.5);
  --btn-bg: #e74c3c;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.card {
  background-color: var(--card-bg);
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 8px 30px var(--card-shadow);
  max-width: 400px;
  text-align: center;
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.toggle-btn {
  background-color: var(--btn-bg);
  color: var(--btn-text);
  border: none;
  padding: 10px 20px;
  font-size: 16px;
  border-radius: 25px;
  cursor: pointer;
  margin-bottom: 20px;
  transition: background-color 0.3s ease;
}

JavaScript

const themeToggle = document.getElementById('theme-toggle');

themeToggle.addEventListener('click', () => {
  document.body.classList.toggle('dark-theme');
});