html,body {
    margin: 0;
    padding: 0;
    overflow: hidden;
}

#loading {
    width: 200px;
    height: 200px;
    position: absolute;
    margin: auto;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    /* transform: translate(-50%, -50%); */
    box-sizing: border-box;
    border-radius: 50%;
    border-top: 10px solid #e74c3c;
    animation: a1 2s linear infinite;
}

#loading::before, #loading::after {
    content: '';
    width: 200px;
    height: 200px;
    position: absolute;
    left: 0;
    top: -10px;
    box-sizing: border-box;
    border-radius: 50%;
}

#loading::before {
    border-top: 10px solid #e67e22;
    transform: rotate(120deg);
}

#loading::after {
    border-top: 10px solid #3498db;
    transform: rotate(240deg);
}

#loading span {
    position: absolute;
    width: 200px;
    height: 200px;
    color: #0097a7;
    text-align: center;
    line-height: 200px;
    animation: a2 2s linear infinite; /*给字体一个反向动画，使其静止不动*/
}

@keyframes a1 {
    to {
        transform: rotate(360deg);
    }
}
@keyframes a2 {
    to {
        transform: rotate(-360deg);
    }
}