小技css3コーディング・時短！

.list {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -ms-flex-wrap: wrap;
    flex-wrap: wrap;
    list-style: none;
    margin-left: -60px;
    margin-top: -60px;
}

.list.col-2 li {
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
    width: calc(50% - 60px);
}
.list .list-item {
    background: #fff;
    border: 1px solid #e3deda;
    margin-left: 60px;
    margin-top: 60px;
}

.nav-list__item+.nav-list__item {
    border-left: 1px dotted #ccc;
}

.nav-list__item {
    -webkit-box-flex: 1;
    flex-grow: 1;
    -ms-flex-positive: 1;
    position: relative;
    text-align: center;
}