.attendees-box ul {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}
.attendees-box li {
    display: -webkit-box;
        display: -ms-flexbox;
            display: flex;
    -webkit-box-pack: center;
        -ms-flex-pack: center;
            justify-content: center;
    -webkit-box-align: center;
        -ms-flex-align: center;
            align-items: center;
    min-height: 48px;
    border: 1px solid rgba(215,170,64,0.4);
    background-color: #1A1A1A;
    box-shadow: 0 2px 30px 0 rgba(0,0,0,0.8);
    color: #FEFEFE;
    font-weight: bold;
    font-size: 18px;
    line-height: 24px;
    list-style: none;
    margin: 8px;
    width: 24%;
    width: calc(25% - 16px);
}

@media only screen and (max-width: 990px) {
    .attendees-box li {
        width: 32%;
        width: calc(33.33333% - 16px);
    }
}

@media only screen and (max-width: 767px) {
    .attendees-box li {
        width: 49%;
        width: calc(50% - 16px);
    }
}

@media only screen and (max-width: 480px) {
    .attendees-box li {
        width: 100%;
    }
}