* { margin: 0; padding: 0; box-sizing: border-box; font-family: Arial, sans-serif; } .menu { width: 250px; background-color: #111; padding: 20px; overflow-y: auto; height: 100vh; box-shadow: 2px 0 10px rgba(255, 0, 255, 0.2); } .menu h3 { text-align: center; color: #b300ff; margin-bottom: 15px; } .menu ul { list-style: none; } .menu ul li { padding: 10px; margin: 5px 0; background: #222; border-left: 4px solid transparent; transition: all 0.3s; cursor: pointer; } .menu ul li:hover { background: #b300ff; border-left: 4px solid #fff; color: #fff; }