<button class="mouse-cursor-gradient-tracking">
                                                            <span>Hover me</span>
                                                          </button>

.mouse-cursor-gradient-tracking {
                                                            position: relative;
                                                            background: #7983ff;
                                                            padding: 0.5rem 1rem;
                                                            font-size: 1.2rem;
                                                            border: none;
                                                            color: white;
                                                            cursor: pointer;
                                                            outline: none;
                                                            overflow: hidden;
                                                          }
                                                          
                                                          .mouse-cursor-gradient-tracking span {
                                                            position: relative;
                                                          }
                                                          
                                                          .mouse-cursor-gradient-tracking:before {
                                                            --size: 0;
                                                            content: '';
                                                            position: absolute;
                                                            left: var(--x);
                                                            top: var(--y);
                                                            width: var(--size);
                                                            height: var(--size);
                                                            background: radial-gradient(circle closest-side, pink, transparent);
                                                            transform: translate(-50%, -50%);
                                                            transition: width 0.2s ease, height 0.2s ease;
                                                          }
                                                          
                                                          .mouse-cursor-gradient-tracking:hover:before {
                                                            --size: 200px;
                                                          }

let btn = document.querySelector('.mouse-cursor-gradient-tracking');
                                                          btn.onmousemove = function(e) {
                                                            let rect = e.target.getBoundingClientRect();
                                                            let x = e.clientX - rect.left;
                                                            let y = e.clientY - rect.top;
                                                            btn.style.setProperty('--x', x + 'px');
                                                            btn.style.setProperty('--y', y + 'px');
                                                          }