.tab-container {
    display: grid;
/*     grid-template-columns: repeat(3, 150px) auto; */
    grid-template-rows: 2em 1px 1fr;
}

.tab {
    display: none;
}

.tab-content {
    background: white;
    display: none;
    padding: 12px;
    grid-column: 1 / 5;
    grid-row: 2 / 4;
}

.tab-label:nth-of-type(1) { grid-column: 1 / 2}
.tab-label:nth-of-type(2) { grid-column: 2 / 3}
.tab-label:nth-of-type(3) { grid-column: 3 / 4}

.tab-label {
    display: block;
/*     width: 150px; */
/*     text-indent: .5em; */
    padding: 0 1em;
    line-height: 2em;
    border: 1px solid #ccc;
    border-bottom: none;
    background: #f5f5f5;
    color: #666;
    position: relative; 
    grid-row: 1 / 2; 
}

.tab:checked + .tab-label {
    color: black;
    background: white;
    grid-row: 1 / 3;
}

.tab:checked + .tab-label + .tab-content {
    display: block;
    border: 1px solid #ccc;
}