.engineering-box ul{
    padding: 0 20px;
    margin: 0 0 30px;
    overflow: hidden;
}
.engineering-box ul li{
    float: left;
    width: calc((100% - 80px) / 4);
    height: calc((1170px - 150px) / 4);
    margin: 10px;
}
.engineering-box ul li a{
    display: block;
    overflow: hidden;
    color: #fff;
    position: relative;
}
.engineering-box ul li a .black-hover{
    opacity: 0;
    transition:opacity 0.5s ease 0s;
    -moz-transition:opacity 0.5s ease 0s; /* Firefox 4 */
    -webkit-transition:opacity 0.5s ease 0s; /* Safari and Chrome */
    -o-transition:opacity 0.5s ease 0s; /* Opera */
}
.engineering-box ul li a:hover .black-hover{
    opacity: 1;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    position: absolute;
    top:0;
}
.engineering-box ul li a:hover .black-hover p{
    margin: 0;
    font-size: 16px;
    padding: 20px;
    line-height: 20px;
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: #111;

}
.engineering-box .engineering-pic{
    height: 100%
}
@media (max-width: 1190px){
    .engineering-box ul li{
        height: calc((970px - 150px) / 4);
    }
}
@media (max-width: 991px){
    .engineering-box ul{
        padding: 0;
    }
    .engineering-box ul li{
        height: calc((750px - 110px) / 4);
    }
}
@media (max-width: 767px){
    .engineering-box ul li{
        height: calc((100vw - 110px) / 4);
    }
}
@media (max-width: 500px){
    .engineering-box ul li{
        width: calc((100% - 40px) / 2);
        height: calc((100vw - 110px) / 2);
    }
}