I want to position a css triangle as a background

Question

I want to build the following layout:

Preferable i want only use css for that. But even with an background-image i wouldn't know how to build it. I searched the web, but didn't find the help i needed.

The Layout contains a div with some text in it. The background-color is a light gray. Then i would love to add a darker triangle background as shown in the picture. This should work as a responsive layout, too.

What i tried:

# html
<div class="wrapper">
    <h1>Das ist ein test</h1>
    <h2>subheadline</h2>
</div>

#css
.wrapper {
  padding-top: 100px;
  text-align: center;
  width: 100%;
  background-color: #4d4d4d;
  height: 400px;
  color: #fff;
  position: relative;
}
.wrapper:before{
  height: 50%;
  width:100%;
  position:relative;
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
  transform: rotate(45deg);
  content:'';
  display:block;
  position:absolute;
  top: 0;
  background-color: #3d3d3d;
}

But this does not work and i can't figure it out on my own.

Thank you for your help!

Answer 1

You can set 2 light gradients on top of the darker background.

They overlap each other and leave only the remaining triangle darker

div {
    width: 400px;
    height: 200px;
    border: solid 1px green;
    background: linear-gradient(to top left, lightgreen 50%, transparent 50%),
    linear-gradient(to top right, lightgreen 50%, transparent 50%), green;
}

<div></div>

Answer 2

Try this one, but still need some work on the responsive part.

.box{
  position: relative;
  width: 100%;
  max-width: 600px;
  background: #ccc;
  min-height: 300px;
}
.box:before {
  width: 0; 
  height: 0;
  content: "";
  position: absolute;
  z-index: 0;
  top: 0;
  left: 0;
  border-left: 300px solid transparent;
  border-right: 300px solid transparent;
  border-top: 180px solid #555;
}

.box .content{
  z-index: 10;
  position: relative;
  color: #fff;
  text-align: center;
  padding-top: 40px;
}

h1, h2{
  margin: 0;
  padding: 0;
}
h2{
  margin-bottom: 80px;
}

.btn{
  background: #f00;
  color: #fff;
  display: inline-block;
  padding: 5px 10px;
  text-align: center;
  text-decoration: none;
  min-width: 200px;
  font-size: 20px;
}

<div class="box">
  <div class="content">
  <h1>Headline</h1>
  <h2>Headline</h2>
    
    <a href="#" class="btn">CTA</a>
  </div><!--// end .content -->
</div><!--// end .box -->

Answer 3

This should get you close, and illustrates a CSS only approach:

* {
  margin: 0;
  padding: 0
}

body {
  background: #ccc;
  min-height: 500px;
}

div {
  width: 0;
  height: 0;
  margin: 0px auto;
  border: 200px solid transparent;
  border-top-color: grey;
}

a {
  display: block;
  background: blue;
  color: white;
  padding: 5px 10px;
  width: 200px;
  margin: 0px auto;
  position: relative;
  top: -200px;
  text-align: center;
  text-decoration: none;
}

<div></div>
<a href="#">link</a>