.container {
  width: 300px;
  height: 200px;
  margin: 50px auto;
  text-align: center;
}
.grid {
  display: grid;
  
  grid-template-columns: 100px 100px 100px;
  grid-template-rows: 100px 100px 100px;
 /*   放置顺序：先行后列 尽量填满*/
  grid-auto-flow: row dense;
}
.item {
  border: 1px solid #000;
  text-align: center;
  line-height: 100px;
}
.item:nth-child(1) {
  background: yellow;
  /*   第一个项目占两个单元格 */
  grid-column-start: 1;
  grid-column-end: 3;
}
.item:nth-child(2) {
  background: #ece8ce;
  /*   第二个项目占两个单元格 */
  grid-column-start: 1;
  grid-column-end: 3; 
}
.item:nth-child(3) {
  background: #f2d1ee;
}
.item:nth-child(4) {
  background: #bde8f2;
}
.item:nth-child(5) {
  background: #fcc677;
}
.item:nth-child(4) {
  background: #bff29f;
}