<div class="loading-mask">
        <div class="loading-text">
            <span style="--i:1">加</span>
            <span style="--i:2">载</span>
            <span style="--i:3">中</span>
            <span style="--i:4">.</span>
            <span style="--i:5">.</span>
            <span style="--i:6">.</span>
        </div>
    </div>

 .loading-mask {
        min-height: 100vh;
        display: flex;
        justify-content: center;
        align-items: center;
        background-color: #000;
        .loading-text {
            font-size: 32px;
            color: #fff;
            span {
                display: inline-block;
                animation: jump 1.5s ease-in-out infinite;
                /* 利用变量设置延迟时间*/
                animation-delay: calc(.1s*var(--i)); 
            }
        }
    }
    @keyframes jump {
        0% {
            transform: translateY(0px);
        }
        20% {
            transform: translateY(-24px);
        }
        40%,
        100% {
            transform: translateY(0px);
        }
    }