1. html

                  <div class="glowing-circle"></div>

                

2. css

                .glowing-circle {
                    width: 100px;
                    height: 100px;
                    border-radius:50%;
                    background-color: #fff;
                    -webkit-animation: glowing 1s ease-in-out infinite alternate;
                    -moz-animation: glowing 1s ease-in-out infinite alternate;
                    animation: glowing 1s ease-in-out infinite alternate;
                  }
                  @-webkit-keyframes glowing {
                    from {
                      box-shadow: 0 0 10px #fff, 0 0 20px #fff, 0 0 30px #f0f, 0 0 40px #0ff, 0 0 50px #e60073, 0 0 60px #e60073, 0 0 70px #e60073;
                    }
                    to {
                      box-shadow: 0 0 20px #fff, 0 0 30px #ff4da6, 0 0 40px #ff4da6, 0 0 50px #ff4da6, 0 0 60px #ff4da6, 0 0 70px #ff4da6, 0 0 80px #ff4da6;
                    }
                  }