跳动的球

        .ball {
            width: 2rem;
            height: 2rem;
            border-radius: 50%;
            position: absolute;
            top: 0;
            background-image: radial-gradient(at 50px 50px , rgba(255,255,255,0),rgba(96,197,241,1));
            animation: aaa 1s ease-in alternate infinite;
        }

        .bg {
            width: 2rem;
            height: 1rem;
            border-radius: 100px 50px;
            animation: bg 1s ease-in alternate infinite;
            position: absolute;
            top: 3rem;
            left: 0;
            background-image:radial-gradient(rgba(191,191,191,0.7),rgba(255,255,255,0));
        }

        @keyframes aaa {
            0% {
                top: 0;
            }
            100% {
                top: 0.5rem;
            }
        }
		
		        @keyframes bg {
            0% {
                transform: scale(0.4);
            }
            100% {
                transform: scale(1);
            }
        }
		
		 // .box {
        //     width: 100%;
        //     margin: 0 auto;
        //     position: relative;
        // }
		
		                <div class="box">
                            <div class="ball"></div>
                            <div class="bg"></div>
                        </div>