Applying multiple mask-image to a single div - html

Question

I can apply a mask-image at any place on a div I want, but can I apply more than one mask-image on the same div?
Example with a single mask-image:
div {
width: 200px;
height: 200px;
background-color: green;
border: 2px solid black;
-webkit-mask-image: radial-gradient(
circle at center top,
transparent 30px,
black 31px
);
}
<div></div>
What would the code look like if I wanted to have the same mask applied at the top and at the bottom at the same time?
div {
width: 200px;
height: 200px;
background-color: green;
border: 2px solid black;
-webkit-mask-image: radial-gradient(
circle at center top,
transparent 30px,
black 31px
), radial-gradient(
circle at center bottom,
transparent 30px,
black 31px
);
}
<div></div>
Edit: I'm aware Chrome supports mask-composite, but that works (at the time of writing this) only with Chrome.

Answer 1

You need to play with the size and position. mask work the same way as background-image so simply imagine your self making two images on the same element (one on the top and the other on the bottom)
div {
width: 200px;
height: 200px;
background-color: green;
border: 2px solid black;
-webkit-mask:
radial-gradient( circle at center top, transparent 30px, black 31px) top,
radial-gradient( circle at center bottom, transparent 30px, black 31px) bottom;
-webkit-mask-size:100% 51%; /* each one half the size */
-webkit-mask-repeat:no-repeat; /* don't forget this */
}
<div></div>
Another idea with one mask:
div {
width: 200px;
height: 200px;
background-color: green;
border: 2px solid black;
-webkit-mask: radial-gradient(circle, transparent 30px, black 31px) 0 100px; /* 100px is half the height */
}
<div></div>
and with the border:
div {
width: 200px;
height: 200px;
background: radial-gradient(circle, transparent 30px, black 0 33px,green 33px) 0 100px border-box;
border: 2px solid black;
-webkit-mask: radial-gradient(circle, transparent 30px, black 31px) 0 100px; /* 100px is half the height */
}
<div></div>
A solution with mask-composite:
div {
width: 200px;
height: 200px;
background-color: green;
border: 2px solid black;
-webkit-mask:
radial-gradient( circle at center top, transparent 30px, black 31px),
radial-gradient( circle at center bottom, transparent 30px, black 31px),
linear-gradient(black,black); /* this layer is mandatory */
-webkit-mask-composite: destination-in;
mask-composite: exclude; /* for non-webkit browser */
}
<div></div>