html, body {
  height: 100%;
}

body {
  background-color: lightskyblue;
    font-family: Arial, Helvetica, sans-serif;
}

h1 {
  text-align: center;
  font-size: 40px;
}

.center-div
{
  position: absolute;
  margin: auto;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  width: 500px;
  height: 500px;
  background-color: #ccc;
  border-radius: 3px;
}

.colorful {
  color: darkblue;
  font-size:30px;
  text-align: center;
}

.status {
  color: red;
  font-size:17px;
  text-align: center;
}
.status span{
  color: black;
}

.button-call {
  background-color:green;
  border: none;
  color: white;
  padding: 15px 32px;
  text-align: center;
  text-decoration: none;
  display: none;
  font-size: 16px;
  /*position: fixed;*/
  bottom: 5px;
  right: 5px;
  margin:10% auto;
}

.button-calling {
  background-color:orange;
  border: none;
  color: white;
  padding: 15px 32px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  position: fixed;
  bottom: 5px;
  right: 5px;
}

.button-hangup {
  background-color:red;
  border: none;
  color: white;
  padding: 15px 32px;
  text-align: center;
  text-decoration: none;
  display: none;
  font-size: 16px;
  margin:10% auto;
  /*position: fixed;*/
  /*bottom: 5px;*/
  /*right: 5px;*/
}
main{
  text-align: center;
}