如何将元素放在圆角中间？

Question

我有一个元素（灰色的）120px / 120px，边界半径为50％，我想把另一个元素（橙色的）放在左上边框的中间。我怎么能这样做？

这是我的代码：

  top: 0;
  left: 60px;
  transform: rotate(45deg);

但元素只围绕它的中心移动。

修改

工作样本：jsfiddle

Answer 1

我设法通过使用一些数学来实现它：

1. 将元素放入top=0 ; left:50%;
2. translateX x = - (height/2 * cos(45deg)) = -60 * 0.707 = -42px
3. 翻译y = height/2 * (1 - sin(45deg)) = 60*(1 - 0.707) = 18px
4. translateX和translateY -50％到中心;

transform: translateX(-50%) translateY(-50%) translateX(-42px) translateY(18px);

修改

要使解决方案具有响应性（如果大圆是40vh / 40vh）：

transform: translateX(-50%) translateY(-50%) translateX(calc(-40vh/2 * 0.707)) translateY(calc(40vh/2 * 0.3));

以下是一个工作示例：jsfiddle

body {
  padding-top: 50px;
}
.big-circle {
  width: 40vh;
  height: 40vh;
  border-radius: 50%;
  background-color: gray;
  position: relative;
}

.small-circle {
  position: absolute;
  width: 30px;
  height: 30px;
  background-color: coral;
  top:0;
  left: 50%;
  border-radius: 50%;
  transform: translateX(-50%) translateY(-50%) translateX(calc(-40vh/2 * 0.707)) translateY(calc(40vh/2 * 0.3));
  color: #fff;
  text-align: center;
  line-height: 30px;
}

<div class="big-circle">
  <div class="small-circle">
  12
  </div>
</div>

Answer 2

根据评论更新

你可以这样做，使用你旋转的包装器，它也会响应

body {
  padding: 50px;
  display: flex;
}
.big-circle, .small-circle {
  position: relative;  
  width: 40vh;
  height: 40vh;
  border-radius: 50%;
  background-color: gray;
}
.small-circle {
  position: absolute;
  left: 0; top: 0;
  transform: rotate(45deg);
}
.small-circle div {
  position: absolute;
  width: 30px;
  height: 30px;
  background-color: coral;
  top: calc(50% - (30px / 2));
  left: -15px;
  border-radius: 50%;
  line-height: 30px;
  transform: rotate(-45deg);      /*  this will reverse the rotation/content  */
}
.big-circle-content {
  position: relative;
  width: 40vh;
  height: 40vh;
  line-height: 40vh;
  border-radius: 50%;
  padding: 0 10px;
  box-sizing: border-box;
}

<div class="big-circle">
  <div class="small-circle">
    <div>123</div>
  </div>
  <div class="big-circle-content">
    Content
  </div>
</div>

<击> 你可以这样做，使用伪，也会响应

Updated fiddle

body {
  padding: 50px;
  display: flex;
}
.big-circle, .small-circle {
  width: 40vh;
  height: 40vh;
  border-radius: 50%;
  background-color: gray;
  position: relative;  
}
.small-circle {
  transform: rotate(45deg);
}
.big-circle:nth-child(2) .small-circle {
  transform: rotate(135deg);
}
.small-circle::after {
  content: '';
  position: absolute;
  width: 30px;
  height: 30px;
  background-color: coral;
  top: calc(50% - (30px / 2));
  left: -15px;
  border-radius: 50%;
}

<div class="big-circle">
  <div class="small-circle">  
  </div>
</div>

<div class="big-circle">
  <div class="small-circle">  
  </div>
</div>

如果big-circle不包含其他元素，您可以删除small-circle元素并在rotate

上设置伪和big-circle

body {
  padding: 50px;
  display: flex;
}
.big-circle {
  width: 40vh;
  height: 40vh;
  border-radius: 50%;
  background-color: gray;
  position: relative;  
  transform: rotate(45deg);
}
.big-circle:nth-child(2) {
  transform: rotate(135deg);
}
.big-circle::after {
  content: '';
  position: absolute;
  width: 30px;
  height: 30px;
  background-color: coral;
  top: calc(50% - (30px / 2));
  left: -15px;
  border-radius: 50%;
}

<div class="big-circle">
</div>

<div class="big-circle">
</div>

Answer 3

只需使用以下代码修改代码：

<强>更新：

.small-circle {
  position: absolute;
  width: 30px;
  height: 30px;
  background-color: coral;
  top:12%;
  left: 20%;
  border-radius: 50%;
  transform: translateX(-50%) translateY(-50%);
}

Answer 4

＆＃13;

＆＃13;

body {
  padding-top: 50px;
}
.big-circle {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background-color: gray;
  position: relative;
}

.small-circle {
  position: relative;
  width: 30px;
  height: 30px;
  background-color: coral;
  top: 5px;
  left: 5px;
  border-radius: 50%;
  //transform: translateX(-50%) translateY(-50%);
}

＆＃13;

<div class="big-circle">
  <div class="small-circle">
  
  </div>
</div>

＆＃13;

＆＃13;

＆＃13;