CSS 元素置中

以下展示三種置中方法 :

<div class="method-container">
  <div class="method-title">Flexbox</div>
  <div class="box">
    <div class="dot"></div>
  </div>
</div>

<div class="method-container">
  <div class="method-title">Absolute </div>
  <div class="box box-absolute">
    <div class="dot"></div>
  </div>
</div>

<div class="method-container">
  <div class="method-title">Margin 0 Auto</div>
  <div class="box" style="position: relative; margin: 0 auto;">
    <div class="dot" style="position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);"></div>
  </div>
</div>

body {
  display: flex;
  justify-content: space-around;
  align-items: center;
  height: 100vh;
  margin: 0;
  background-color: #f0f0f0;
}

.method-container {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.method-title {
  margin-bottom: 10px;
  font-weight: bold;
}

.box {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 200px;
  height: 200px;
  border: 1px solid red;
  margin-bottom: 20px;
}

.box-absolute {
  position: relative;
}

.box-absolute div {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.dot {
  width: 20px;
  height: 20px;
  background-color: red;
  border-radius: 50%;
}