如何绘制树结构的线条

Question

我使用 css grid 来输出图像中显示的元素的确切结构。唯一缺少的是您在下图中看到的线条。最重要的是代码简洁、干净和 DRY。我在考虑使用伪元素，只是它不会帮助编写可读的代码。

.three {
  display: grid;
  grid-template-rows: repeat(7, 100px);
  grid-template-columns: repeat(3, 1fr);
  grid-gap: 1em;
  
  grid-template-areas:
  
     ".  C  ."
     ".  .  B-1"     
     "A  B  B-2"     
     ".  .  B-3"
     ".  D  ."
     ".  E  .";
}

.A   { grid-area: A; }
.B   { grid-area: B; }
.C   { grid-area: C; }
.D   { grid-area: D; }
.E   { grid-area: E; }
.B-1 { grid-area: B-1; }
.B-2 { grid-area: B-2; }
.B-3 { grid-area: B-3; }

.unordered-list {
  background-color: lightgreen;
  list-style-type: none;
  display: flex;
  justify-content: center;
  align-items: center;
}

<ul class="three">
  <li class="unordered-list A">A</li>
  <li class="unordered-list B">B</li>
  <li class="unordered-list C">C</li>
  <li class="unordered-list D">D</li>
  <li class="unordered-list E">E</li>  
  <li class="unordered-list B-1">B-1</li>
  <li class="unordered-list B-2">B-2</li>
  <li class="unordered-list B-3">B-3</li>
</ul>

Answer 1

这是我尝试使用::beforeand ::after：

.three {
  display: grid;
  grid-template-rows: repeat(7, 100px);
  grid-template-columns: repeat(3, 1fr);
  grid-gap: 1em;
  width: 44rem;
  grid-template-areas: ".  C  ." ".  .  B-1" "A  B  B-2" ".  .  B-3" ".  D  ." ".  E  .";
}

li {
  position: relative;
}

.A {
  grid-area: A;
}

.B {
  grid-area: B;
}

.C {
  grid-area: C;
}

.D {
  grid-area: D;
}

.E {
  grid-area: E;
}

.B-1 {
  grid-area: B-1;
}

.B-2 {
  grid-area: B-2;
}

.B-3 {
  grid-area: B-3;
}

.A::after,
.B::after {
  content: "";
  position: absolute;
  right: 0;
  transform: translateX(100%);
  display: block;
  background: grey;
  width: 45px;
  height: 3px;
}

.B-1::before,
.B-3::before,
.C::before,
.D::before,
.E::before {
  content: "";
  position: absolute;
  left: 0;
  transform: translateX(-100%);
  display: block;
  background: grey;
  width: 20px;
  height: 3px;
}

.B::before,
.B-2::before {
  content: "";
  position: absolute;
  left: 0;
  transform: translateX(-23px);
  display: block;
  background: grey;
  width: 3px;
  height: 235px;
  border-top-left-radius: 5px;
  border-bottom-left-radius: 5px;
}

.B::before {
  height: 583px;
  transform: translate(-23px, 58px);
}

.unordered-list {
  background-color: lightgreen;
  list-style-type: none;
  display: flex;
  justify-content: center;
  align-items: center;
}

li {
  border-top-left-radius: 5px;
  border-bottom-right-radius: 5px;
  width: 200px;
}

<ul class="three">
  <li class="unordered-list A">A</li>
  <li class="unordered-list B">B</li>
  <li class="unordered-list C">C</li>
  <li class="unordered-list D">D</li>
  <li class="unordered-list E">E</li>
  <li class="unordered-list B-1">B-1</li>
  <li class="unordered-list B-2">B-2</li>
  <li class="unordered-list B-3">B-3</li>
</ul>

它没有响应，但它完成了工作。如果有人可以使其响应，我很乐意看到它。