CSS3 moon shape

Question

I am trying to create a button like this:

I dont know how to create a light moon shape over the top of the button.

This is still far off: Fiddle Demo.

.moon {
   width: 50px;
   height: 50px;
   border-radius: 50%;
   box-shadow: 15px 15px 0 0 green;
}

Answer 1

With just a little inset you can style the shadow on top of the object.

E.g. Crescent shape.

And, This is the button you want.

.moon {
  background-color: #222;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  border: 4px solid #222;
  /* I set 2 shadows where the first one doesn't have blur and spread for firefox fix. */
  box-shadow: inset 0px 16px #999, inset 0px 16px 1px 1px #999;
  -moz-box-shadow: inset 0px 16px #999, inset 0px 16px 1px 1px #999;
}

<div class="moon"></div>