点击按钮时如何将label居中定位在弹出框顶部

解决方案 #

仅需修改CSS部分即可实现预期效果，无需调整HTML结构，修改点如下：

1. 移除label的固定左边距，避免居中时出现偏移
2. 给label添加过渡动画，实现位移的平滑效果
3. 针对按钮激活/聚焦状态单独设置label的居中定位规则
4. 下调列表内容的垂直位置，避免和顶部label重叠

修改后的完整CSS代码：

div {
  position: relative;
  box-sizing: border-box;
}

p {
  font-size: 9pt;
  margin-bottom: 1pt;
  margin-top: 2.5pt;
  margin-left: 2px;
  z-index: 5;
}

a {
  color: inherit;
  text-decoration: none;
}

label {
  font-size: 10pt;
  margin: 0;
  color: #e26030;
  font-weight: bold;
}

.centered-y {
  position: absolute;
  width: 100%;
  height: 100%;
  top: calc(50% + 10px);
  -webkit-transform: translateY(-50%);
  transform: translateY(-50%);
}

.test {
  position: absolute;
  top: -2px;
  left: 16px;
  transition: all 0.25s ease-in-out 0.25s;
}

.distribution-map {
  position: relative;
  width: 100%;
  height: 500%;
  padding: 20px;
  box-sizing: border-box;
  margin: 0 auto;
  background: white;
}

.distribution-map .map-point {
  cursor: pointer;
  outline: none;
  z-index: 0;
  position: absolute;
  width: 13px;
  height: 13px;
  border-radius: 15px;
  -webkit-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  -moz-transition: opacity 0.25s ease-in-out 0.25s, width 0.25s ease-in-out 0.25s, height 0.25s ease-in-out 0.25s, z-index 0.25s ease-in-out 0.25s;
  -o-transition: opacity 0.25s ease-in-out 0.25s, width 0.25s ease-in-out 0.25s, height 0.25s ease-in-out 0.25s, z-index 0.25s ease-in-out 0.25s;
  -webkit-transition: opacity 0.25s ease-in-out, width 0.25s ease-in-out, height 0.25s ease-in-out, z-index 0.25s ease-in-out;
  -webkit-transition-delay: 0.25s, 0.25s, 0.25s, 0.25s;
  transition: opacity 0.25s ease-in-out 0.25s, width 0.25s ease-in-out 0.25s, height 0.25s ease-in-out 0.25s, z-index 0.25s ease-in-out 0.25s;
  background: rgba(26, 26, 26, 0.85);
  border: 2.5px solid #e26030;
}

.distribution-map .map-point .content {
  opacity: 0;
  transition: opacity 0.25s ease-in-out;
  width: 100%;
  height: 100%;
  left: 50%;
  -webkit-transform: translateX(-50%);
  transform: translateX(-50%);
  overflow: overlay;
}

.distribution-map .map-point:active,
.distribution-map .map-point:focus {
  margin: 0;
  padding: 0;
  opacity: 1;
  width: 100px;
  height: 100px;
  color: #e5e5e5;
  z-index: 1;
  transition: opacity 0.25s ease-in-out, width 0.25s ease-in-out, height 0.25s ease-in-out;
}

.distribution-map .map-point:active .test,
.distribution-map .map-point:focus .test {
  left: 50%;
  top: 8px;
  transform: translateX(-50%);
}

.distribution-map .map-point:active .content,
.distribution-map .map-point:focus .content {
  opacity: 1;
  -moz-transition: opacity 0.25s ease-in-out 0.25s, height 0.25s ease-in-out, overflow 0.25s ease-in-out;
  -o-transition: opacity 0.25s ease-in-out 0.25s, height 0.25s ease-in-out, overflow 0.25s ease-in-out;
  -webkit-transition: opacity 0.25s ease-in-out, height 0.25s ease-in-out, overflow 0.25s ease-in-out;
  -webkit-transition-delay: 0.25s, 0s, 0s;
  transition: opacity 0.25s ease-in-out 0.25s, height 0.25s ease-in-out, overflow 0.25s ease-in-out;
  overflow: hidden;
}

.distribution-map .map-point:active .content a:hover,
.distribution-map .map-point:active .content a:active,
.distribution-map .map-point:focus .content a:hover,
.distribution-map .map-point:focus .content a:active {
  color: #afe1fa;
}

修改完成后，点击按钮时label会从按钮侧边平滑移动到弹出框顶部居中位置，不会出现偏移问题，也不会和下方列表内容重叠。

内容的提问来源于stack exchange，提问作者W.Diaz