taro/src/custom-tab-bar/index.scss

.tabbar{
    display: flex;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 103px;
    flex-direction: row;
    justify-content: space-around;
    background-color: #000;
    // background-color: #000;
    // background-color: red;
    padding-bottom: constant(safe-area-inset-bottom);
    /* 兼容 iOS < 11.2 */
    padding-bottom: env(safe-area-inset-bottom);
    border-top-color: rgba($color: #ffffff, $alpha: 0.2);
    border-top-width: 1px;
    border-top-style: solid;
    z-index: 100;
}

//未选中 18 40%
//选中 20 100%

.tabbar-item{
    color: rgba($color: #ffffff, $alpha: 0.4);
    font-size: 36px;
    // padding-top: 25px;
    display: flex;
    flex: 1;
    align-items: center;
    justify-content: center;
}

.tabbar-item-sel{
    color: #ffffff;
    font-size: 40px;
}