transparent shape with arrow in upper corner

Question

Please see the image below.

I want to add an arrow to the top right of a div

Answer 1

Filter: drop-shadow()

The compatibility is limited

Yet the effect is pretty cool :P

.inputcontainer {
  display: inline-block;
  position: relative;
  filter: drop-shadow(0px 0px 5px black);
  -webkit-filter: drop-shadow(0px 0px 1px black);
}
.input {
  display: inline-block;
  border: none;
  border-radius: 10px;
  border-top-right-radius: 0px;
  width: 280px;
  height: 50px;
  background-color: white;
  padding-left: 20px;
  font-size: 20px;
}
.input:focus {
  outline: none;
}
.arrow {
  position: absolute;
  display: inline-block;
  top: 0;
  right: -5px;
  width: 20px;
  height: 20px;
  background-color: white;
  transform: skew(-45deg);
  z-index: -1;
}

Box-shadow:

Here the compatibility is a lot better

.inputcontainer {
  display: inline-block;
  position: relative;
  filter: drop-shadow(0px 0px 5px black);
}
.input {
  display: inline-block;
  border: none;
  border-radius: 10px;
  border-top-right-radius: 0px;
  width: 280px;
  height: 50px;
  background-color: white;
  padding-left: 20px;
  font-size: 20px;
  box-shadow: 0px 0px 0px 2px gray;
}
.input:focus {
  outline: none;
}
.arrow {
  position: absolute;
  display: inline-block;
  top: 0;
  right: -8px;
  width: 20px;
  height: 20px;
  background-color: white;
  transform: skew(-45deg);
  box-shadow: 2px -2px 0px 0px gray;
}