.tabs {
  width: 100%;
  --border: #666666;
  --surface: #fff;
}

.tabs input[type=radio] {
    display: none;
}

.tabs label {
    display: inline-block;
    padding: 10px 14px;
    margin-right: 4px;
    cursor: pointer;
    border: 1px solid var(--border);
    border-bottom: none;                 /* let the panel border be the bottom */
    border-radius: 6px 6px 0 0;
    background: transparent;
    position: relative;
    font-size: 80%;
    font-weight: bold;
}

.tabs input:checked + label {
    z-index: 1;
    background: var(--surface);
    border-bottom: 2px solid var(--surface);
}

.tab-panel {
    display: none;
    padding: 0.5em;
    border: 1px solid var(--border);
    border-radius: 0 6px 6px 6px;
    margin-top: -2px;                    /* stitch to labels */
    background: var(--surface);
}

/* Show the selected one */
#tab1:checked ~ #panel1,
#tab2:checked ~ #panel2,
#tab3:checked ~ #panel3 {
    display: block;
}