实现效果：
实现源码:
CSS部分：
.tree summary {
outline: 0;
padding-left: 30px;
list-style: none;
background: repeating-linear-gradient(
90deg,
#999 0 1px,
transparent 0px 2px
)
0px 50%/20px 1px no-repeat;
/* background: linear-gradient(#999,#999) 0px 50%/20px 1px no-repeat; */
}
.tree details:last-child {
background-size: 1px 23px;
}
.tree > details:not(:last-child) > details:last-child {
background-size: 1px 100%;
}
.tree details {
padding-left: 40px;
background: repeating-linear-gradient(#999 0 1px, transparent 0px 2px)
40px 0px/1px 100% no-repeat;
/* background: linear-gradient(#999, #999) 40px 0px/1px 100% no-repeat; */
}
.tree > details {
background: none;
padding-left: 0;
}
.tree > details > summary {
background: none;
}
.tree summary {
display: flex;
align-items: center;
height: 46px;
font-size: 15px;
line-height: 22px;
color: rgba(0, 0, 0, 0.85);
cursor: default;
}
.tree summary::after {
content: "";
position: absolute;
left: 10px;
right: 10px;
height: 38px;
background: #eef2ff;
border-radius: 8px;
z-index: -1;
opacity: 0;
transition: 0.2s;
}
.tree summary:hover::after {
opacity: 1;
}
.tree summary:not(:only-child)::before {
content: "";
width: 14px;
height: 14px;
flex-shrink: 0;
margin-right: 8px;
border: 1px solid #999;
background: linear-gradient(#999, #999) 50%/1px 10px no-repeat,
linear-gradient(#999, #999) 50%/10px 1px no-repeat;
}
.tree details[open] > summary::before {
background: linear-gradient(#999, #999) 50%/10px 1px no-repeat;
}
HTML部分
<div class="tree">
<details>
<summary>目录-</summary>
<!--没有内容了-->
<details>
<summary>1-1</summary>
</details>
<details>
<summary>1-2</summary>
</details>
<details>
<summary>1-3</summary>
</details>
</details>
<details>
<summary>目录二</summary>
<details>
<summary>2-1</summary>
<details>
<summary>2-1-1</summary>
<details>
<summary>2-1-1-1</summary>
</details>
</details>
<details>
<summary>2-1-2</summary>
</details>
<details>
<summary>2-1-3</summary>
</details>
</details>
<details>
<summary>2-2</summary>
</details>
<details>
<summary>2-3</summary>
</details>
</details>
<details>
<summary>目录五</summary>
<!--没有内容了-->
</details>
</div>
```
如果这些效果对你有所帮助，麻烦点个关注，以下为本人公众号
