一，流光按钮 CSS 样式

.btn{
    width: 100px;
    height: 50px;
    border-radius: 50px;
    text-align: center;
    background-color:aqua;
    line-height: 50px;
    background-image: linear-gradient(to left , #EAD6EE,#A0F1EA,rgb(124, 241, 241),#e3a5f0,#EAD6EE);
    background-size: 400%; 
}
@keyframes run{
    100%{
        background-position: 400% 0px;
    }
}
.btn:hover{
    animation: run 4s linear 0s infinite;
}

二，冷光按钮 CSS 样式

来源：https://github.com/luoyunqa/cool_lights_for_button

button{
    position: relative;
    height: 60px;
    width: 200px;
    margin: 0 35px;
    border-radius: 50px;
    border: none;
    outline: none;
    background: #111;
    color: #fff;
    font-size: 20px;
    letter-spacing: 2px;
    text-transform: uppercase;
    cursor: pointer
}


button:first-child:hover{
    background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
    background-size: 400%;
}



button:last-child:hover{
    background: linear-gradient(90deg, #fa7199, #f5ce62, #e43603, #fa7199);
    background-size: 400%;
}


button:first-child:before,
button:last-child:before{
    content: '';
    position: absolute;
    background: inherit;
    top: -5px;
    right:-5px;
    bottom: -5px;
    left: -5px;
    border-radius: 50px;
    filter: blur(20px);
    opacity: 0;
    transition: opacity 0.5s;
}


button:first-child:hover:before,
button:last-child:hover:before{
    opacity: 1;
    z-index: -1;
}


button:hover{
    z-index: 1;
    animation: glow 8s linear infinite;
}


@keyframes glow {
    0%{
        background-position: 0%;
    }
    100%{
        background-position: 400%;
    }
}