  display: grid;
  grid-template-columns: subgrid;
  grid-column: 3 / span 4;
  grid-auto-rows: 8px;
  background: grey;
}

.subgrid > :nth-child(2n)   {  background: black; }
.subgrid > :nth-child(2n+1) {  background: pink; }

  </style>
</head>
<body>

<div class="grid">
  <div class="subgrid">
    <div style="grid-column:5"></div>
    <div style="grid-column:x"></div>
    <div style="grid-column:5"></div>
    <div></div>
    <div style="grid-column:5"></div>
  </div>
</div>

<div class="grid">
  <div cla