.ms-block-countdown.ms-block-theme-calendar span b {
    position: relative;
    height: 2em;
    width: 2em;
    font-size: 200%;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #fff;
    border-radius: 8px;
    -moz-box-shadow: 0 3px 4px 0 rgba(0, 0, 0, 0.2), inset 2px 4px 0 0 rgba(255, 255, 255, 0.08);
    -webkit-box-shadow: 0 3px 4px 0 rgba(0, 0, 0, 0.2), inset 2px 4px 0 0 rgba(255, 255, 255, 0.08);
    box-shadow: 0 3px 4px 0 rgba(0, 0, 0, 0.2), inset 2px 4px 0 0 rgba(255, 255, 255, 0.08);
}
.ms-block-countdown.ms-block-theme-calendar span:last-child b {
    margin-right: 0;
}

.ms-block-countdown.ms-block-theme-calendar span b:after {
    z-index: 1;
}
.ms-block-countdown.ms-block-theme-calendar span b:after {
    content: "";
    position: absolute;
    display: block;
    top: 0;
    left: 0;
    width: 100%;
    height: 50%;
    background-color: rgba(0, 0, 0, 0.02);
}

.ms-block-countdown.ms-block-theme-calendar span span {
    padding: 5px 0;
}