Negative Border Radius in CSS?

Question

I\'m trying to do CSS to make a div that looks like this:

I\'m pretty much started with this:

.player {
    width: 480px;
    height: 80px;
    bord         


        

Answer 1

Here's yet another way of doing it, this time using a radial background image. This lets it be transparent and works in both Firefox and Chrome.

.player {
  width: 480px;
  height: 80px;
  border-radius: 40px;
  background-image: radial-gradient(circle at 38px 40px, rgba(0, 0, 0, 0) 0, rgba(0, 0, 0, 0) 40px, blue 40px);
  color: #FFF;
}

<div class="player"></div>

Answer 2

.wrapper {
    width: 500px;
    height: 103px;
    background-color: red;
    padding-top: 15px;
}

.player {
    width: 480px;
    height: 83px;
    margin-left: 10px;
    border-top-right-radius: 40px;
    border-bottom-right-radius: 40px;
    border: 1px solid black;
    border-left: none;
    background-color: blue;
    -webkit-mask-image: radial-gradient(circle at left, transparent 0, transparent 40px, black 41px);
}

<div class="wrapper"><div class="player"></div></div>

Answer 3

You can use the before pseudo element to provide the "cut out"

.player {
    width: 480px;
    height: 80px;
    border-radius:0 40px 40px 0;
    background-color:#0000FF;
    position:relative;    
    color:#FFF;
}

.player:before
{
    width: 80px;
    height: 80px;
    border-radius:0 40px 40px 0;
    background-color:#FFF;    
    display:inline-block;
    vertical-align: middle;
    margin-right: 10px;
    content: '';
}

<div class="player">Some Content</div>