I am using CSS Grid, which works great, but want to have a background SVG that the grid sits on top of.

For example, here is the HTML:

<div className="wrapper">
    <div className="item">
        <div id="wave">
            <svg viewBox="0 0 500 200" preserveAspectRatio="none"><path d="M0.00,92.27 C216.83,192.92 304.30,8.39 500.00,109.03 L500.00,0.00 L0.00,0.00 Z"></path></svg>
        </div>
    </div>
    <div className="item">1</div>
    <div className="item">2</div>
    <div className="item">3</div>
</div>

...and the CSS:

.wrapper {
    display: grid;
    grid-template-rows: 100px 100px 100px 100px;
    grid-template-columns: 100vw;
    gap: 10px;
    width: 100vw;
    height: auto;
}

.item {
    background: rgba(0, 0, 0, 0.5);
}

...which obviously only places the SVG in the top row. How can I sit the SVG behind the grid? I also tried wrapping the wrapper with a div and seeing the position to absolute.

Should look like this (svg wave in blue, grid items in pink):

CodePudding user response：

Using the wrapper approach:

1. Create a wrapper element with position: relative.
2. Add the svg element with position: absolute and top: 0, right: 0, etc...
3. Add the grid element with position: relative.

The wrapper having position: relative allows the svg to size itself using the wrapper as its parent. The position: relative on the grid creates a new stacking context above the svg which also has its own stacking context thanks to position: absolute.

Here's a demo:

.wrapper {
  position: relative;
}

.wrapper svg {
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
  fill: lightblue;
}

.grid {
  display: grid;
  grid-template-rows: 100px 100px 100px 100px;
  grid-template-columns: 100%;
  border: 1px solid black;
  gap: 10px;
  position: relative;
}

.item {
  background-color: rgba(0, 0, 0, 0.5);
}

<div class="wrapper">
  <svg viewBox="0 0 500 200" preserveAspectRatio="none">
    <path d="M0.00,92.27 C216.83,192.92 304.30,8.39 500.00,109.03 L500.00,0.00 L0.00,0.00 Z"></path>
  </svg>
  <div class="grid">
    <div class="item">1</div>
    <div class="item">2</div>
    <div class="item">3</div>
    <div class="item">4</div>
  </div>
</div>