CSS 网格无法按预期工作（网格区域）

Question

有人可以帮我弄清楚为什么以下CSS Grid示例无法按预期工作吗？这是Codepen的链接：

.cards {
  margin: 0;
  padding: 1em;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-gap: 20px;
  grid-template-areas:
    "a a b"
    "c d d"
    "c e e";
}

.card {
  background-color: #1E88E5;
  padding: 2em;
  color: #FFFFFF;
  line-height: 1.4;
  border-radius: 4px;
}

.card1 { grid-area: "a"; }
.card2 { grid-area: "b"; background-color: #4CAF50; }
.card3 { grid-area: "c"; background-color: #FFCA28; }
.card4 { grid-area: "d"; background-color: #F06292; }
.card5 { grid-area: "e"; background-color: #FF8A80; }

由于某种原因，网格区域的结构不正确。可能我忘记了一些东西，但我无法弄清楚到底是什么。任何帮助表示赞赏。谢谢！

Answer 1

只需从值中删除引号：grid-area

.card1 { grid-area: a; }
.card2 { grid-area: b; background-color: #4CAF50; }
.card3 { grid-area: c; background-color: #FFCA28; }
.card4 { grid-area: d; background-color: #F06292; }
.card5 { grid-area: e; background-color: #FF8A80; }

.card1 { grid-area: a; }
.card2 { grid-area: b; background-color: #4CAF50; }
.card3 { grid-area: c; background-color: #FFCA28; }
.card4 { grid-area: d; background-color: #F06292; }
.card5 { grid-area: e; background-color: #FF8A80; }

body {
  text-align: center;
}

.wrap {
  max-width: 70em;
  text-align: left;
  margin: 0 auto;
}

.cards {
  margin: 0;
  padding: 1em;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-gap: 20px;
  grid-template-areas:
    "a a b"
    "c d d"
    "c e e";
}

.card {
  background-color: #1E88E5;
  padding: 2em;
  color: #FFFFFF;
  line-height: 1.4;
  border-radius: 4px;
  
  h3 {
    margin-top: 0;
  }
}

.card1 { grid-area: a; }
.card2 { grid-area: b; background-color: #4CAF50; }
.card3 { grid-area: c; background-color: #FFCA28; }
.card4 { grid-area: d; background-color: #F06292; }
.card5 { grid-area: e; background-color: #FF8A80; }