CSS 网格，绝对定位 css 网格元素中的元素 : IMPOSSIBLE

Question

我有这种情况:https://jsfiddle.net/rozkvsdh/5/

一个 CSS 网格，很简单，但在某些元素中，我需要放置一条丝带或另一个 div。

这不可能!

我该怎么办？

 grid-item {
  background-color: lightgreen;
  display: flex;
  justify-content: center;
  align-items: center;
}

.ribbon-wrapper {
  width: 85px; // the length should be not in px I think!
  height: 88px; // the length should be not in px I think!
  overflow: hidden;
  //position: absolute; it doesn't work!
  position: relative;
  top: -3px;
  left: -3px;
  .ribbon {
    font: bold 15px sans-serif;
    color: #333;
    text-align: center;
    -webkit-transform: rotate(-45deg);
    -moz-transform: rotate(-45deg);
    -ms-transform: rotate(-45deg);
    -o-transform: rotate(-45deg);
    position: relative;
    padding: 7px 0;
    top: 15px;
    left: -30px;
    width: 120px;
    background-color: #ebb134;
    color: #fff;
  }
}

Answer 1

你可以使用伪和 data attribute :

HTML5 is designed with extensibility in mind for data that should be associated with a particular element but need not have any defined meaning. data-* attributes allow us to store extra information on standard, semantic HTML elements without other hacks such as non-standard attributes, extra properties on DOM

可以使用overflow和background-clip可以帮助模仿丝带站在外面一点

The background-clip CSS property specifies whether an element's background, either the color or image, extends underneath its border.

vmin or vmax units可用于设置字体大小以通过填充和坐标上的 em 调整功能区的大小。

The viewport-percentage lengths are relative to the size of the initial containing block. When the height or width of the initial containing block is changed, they are scaled accordingly.

最终，可以添加shadow，linear-gradient可以帮助绘制倾斜阴影的部分。

演示:

body {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  grid-auto-rows: 1fr;
  grid-gap: 2px;
  height: 100vh;
  padding: 5px;
  margin: 0;
  box-sizing: border-box;
}

grid-item {
  background-color: lightgreen;
  background-clip: content-box;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding: 3px;
}

grid-item[data-class="new"]:before {
  content: attr(data-class);
  position: absolute;
  font-size: 2vmax; /* update font-size */
  top: 0.4em;
  left: -1.3em;
  padding: 0em 1.5em;
  transform: rotate(315deg);
  background-color:gold;
  /* eventually add some shadow effects */
  background-image: 
  linear-gradient(135deg, black 0.9em, transparent 1.15em), 
  linear-gradient(-135deg, black 0.9em, transparent 1.15em);
  box-shadow: 0 0 3px;
}

<grid-item>see</grid-item>
<grid-item>full</grid-item>
<grid-item>page</grid-item>
<grid-item>then</grid-item>
<grid-item data-class="new">RESIZE</grid-item>
<grid-item>window</grid-item>
<grid-item>to</grid-item>
<grid-item>see</grid-item>
<grid-item>ribbon</grid-item>
<grid-item data-class="new">font&size</grid-item>
<grid-item>updates</grid-item>
<grid-item>F</grid-item>
<grid-item data-class="new">PRO</grid-item>
<grid-item>B</grid-item>
<grid-item>C</grid-item>
<grid-item>D</grid-item>
<grid-item>E</grid-item>
<grid-item>F</grid-item>
<grid-item>A</grid-item>
<grid-item>B</grid-item>