html - 如何使这个 CSS 树居中？

Question

我尝试将浮动的值更改为无，而不是在 .tree li & justify-content: center 中留下浮动。请帮我把这个 CSS 树从左边居中。感谢您提前帮助我。

.tree ul {
    padding-top: 20px; position: relative;
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

.tree li {
    float: left; text-align: center;
    list-style-type: none;
    position: relative;
    padding: 20px 5px 0 5px;
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

/*We will use ::before and ::after to draw the connectors*/

.tree li::before, .tree li::after{
    content: '';
    position: absolute; top: 0; right: 50%;
    border-top: 1px solid #ccc;
    width: 50%; height: 20px;
}
.tree li::after{
    right: auto; left: 50%;
    border-left: 1px solid #ccc;
}

/*We need to remove left-right connectors from elements without
any siblings*/
.tree li:only-child::after, .tree li:only-child::before {
    display: none;
}

/*Remove space from the top of single children*/
.tree li:only-child{ padding-top: 0;}

/*Remove left connector from first child and
right connector from last child*/
.tree li:first-child::before, .tree li:last-child::after{
    border: 0 none;
}
/*Adding back the vertical connector to the last nodes*/
.tree li:last-child::before{
    border-right: 1px solid #ccc;
    border-radius: 0 5px 0 0;
    -webkit-border-radius: 0 5px 0 0;
    -moz-border-radius: 0 5px 0 0;
}
.tree li:first-child::after{
    border-radius: 5px 0 0 0;
    -webkit-border-radius: 5px 0 0 0;
    -moz-border-radius: 5px 0 0 0;
}

/*Time to add downward connectors from parents*/
.tree ul ul::before{
    content: '';
    position: absolute; top: 0; left: 50%;
    border-left: 1px solid #ccc;
    width: 0; height: 20px;
}

.tree li a{
    border: 1px solid #ccc;
    padding: 20px 45px;
    text-decoration: none;
    color: #333;
    font-family: "Roboto", sans-serif;
    font-size: 20px;
    display: inline-block;

    border-radius: 28px;
    -webkit-border-radius: 28px;
    -moz-border-radius: 28px;

    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

/*Time for some hover effects*/
/*We will apply the hover effect the the lineage of the element also*/
.tree li a:hover, .tree li a:hover+ul li a {
    background: #e9453f; color: #fff; border: 1px solid #e9453f;
}
/*Connector styles on hover*/
.tree li a:hover+ul li::after,
.tree li a:hover+ul li::before,
.tree li a:hover+ul::before,
.tree li a:hover+ul ul::before{
    border-color:  #e9453f;
}

<div class="tree">
  <ul>
    <li>
      <a href="#">parent</a>
       <ul>
        <li>
          <a href="#">child</a>
        </li>
        <li>
          <a href="#">child</a>
        </li>
      </ul>
    </li>
  </ul>
</div>

标签： htmlcss

Answer 1

你需要在你的 div.tree 中将你的 ul 居中，并且你需要你的 ul 有一个自动宽度，而不是 100%：

.tree {
    display: grid;
    place-items: center;
}

.tree ul {
    padding-top: 20px; position: relative;
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

.tree li {
    float: left; text-align: center;
    list-style-type: none;
    position: relative;
    padding: 20px 5px 0 5px;
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

/*We will use ::before and ::after to draw the connectors*/

.tree li::before, .tree li::after{
    content: '';
    position: absolute; top: 0; right: 50%;
    border-top: 1px solid #ccc;
    width: 50%; height: 20px;
}
.tree li::after{
    right: auto; left: 50%;
    border-left: 1px solid #ccc;
}

/*We need to remove left-right connectors from elements without
any siblings*/
.tree li:only-child::after, .tree li:only-child::before {
    display: none;
}

/*Remove space from the top of single children*/
.tree li:only-child{ padding-top: 0;}

/*Remove left connector from first child and
right connector from last child*/
.tree li:first-child::before, .tree li:last-child::after{
    border: 0 none;
}
/*Adding back the vertical connector to the last nodes*/
.tree li:last-child::before{
    border-right: 1px solid #ccc;
    border-radius: 0 5px 0 0;
    -webkit-border-radius: 0 5px 0 0;
    -moz-border-radius: 0 5px 0 0;
}
.tree li:first-child::after{
    border-radius: 5px 0 0 0;
    -webkit-border-radius: 5px 0 0 0;
    -moz-border-radius: 5px 0 0 0;
}

/*Time to add downward connectors from parents*/
.tree ul ul::before{
    content: '';
    position: absolute; top: 0; left: 50%;
    border-left: 1px solid #ccc;
    width: 0; height: 20px;
}

.tree li a{
    border: 1px solid #ccc;
    padding: 20px 45px;
    text-decoration: none;
    color: #333;
    font-family: "Roboto", sans-serif;
    font-size: 20px;
    display: inline-block;

    border-radius: 28px;
    -webkit-border-radius: 28px;
    -moz-border-radius: 28px;

    transition: all 0.5s;
    -webkit-transition: all 0.5s;
    -moz-transition: all 0.5s;
}

/*Time for some hover effects*/
/*We will apply the hover effect the the lineage of the element also*/
.tree li a:hover, .tree li a:hover+ul li a {
    background: #e9453f; color: #fff; border: 1px solid #e9453f;
}
/*Connector styles on hover*/
.tree li a:hover+ul li::after,
.tree li a:hover+ul li::before,
.tree li a:hover+ul::before,
.tree li a:hover+ul ul::before{
    border-color:  #e9453f;
}

<div class="tree">
  <ul>
    <li>
      <a href="#">parent</a>
       <ul>
        <li>
          <a href="#">child</a>
        </li>
        <li>
          <a href="#">child</a>
        </li>
      </ul>
    </li>
  </ul>
</div>