Html Css Javascript Crash Course -
// Toggle theme on button click button.addEventListener('click', () => body.classList.toggle('dark');
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Theme Switcher | Crash Course</title> <link rel="stylesheet" href="style.css"> </head> <body> <div class="container"> <h1>🎨 HTML + CSS + JS Crash Course</h1> <p>Click the button to switch between light and dark themes.</p> <button id="themeBtn">🌙 Dark Mode</button> <div class="demo-box"> <p>This box changes style with the theme!</p> </div> </div> <script src="script.js"></script> </body> </html> CSS handles colors, fonts, spacing, and responsiveness.
.demo-box background: var(--box-bg); border: 1px solid var(--box-border); border-radius: 12px; padding: 1.5rem; margin: 2rem 0; transition: 0.2s; html css javascript crash course
button background: var(--btn-bg); color: var(--btn-text); border: none; padding: 10px 20px; font-size: 1rem; border-radius: 30px; cursor: pointer; transition: 0.2s;
JavaScript adds logic and user interaction. // Toggle theme on button click button
.container max-width: 600px; margin: 0 auto; text-align: center;
// Update button text & save preference if (body.classList.contains('dark')) button.textContent = '☀️ Light Mode'; localStorage.setItem('theme', 'dark'); else button.textContent = '🌙 Dark Mode'; localStorage.setItem('theme', 'light'); meta name="viewport" content="width=device-width
button:hover transform: scale(1.02); opacity: 0.9;