.keyboard{
  width: 100vw;
}
.key-rows{ 
  display:flex;
  width: 100vw;
}
.key{
  width: 25vw;
}
.key button{
  margin: 1vh 1vw;
  height:8.6vh;
  line-height:8.6vh;
}
.screen{
  width: 98vw;
  height:44vh;
  margin: 1vh 1vw;
  padding: 1vh 1.4vw;
  border:1px solid #353535;
  box-sizing:border-box;
  border-radius:4px;
}
.screen button{
  text-align:right;
  margin: 0;
  line-height:8vh;
  height:8vh;
  border:none;
  color: gainsboro;
  font-size:7vw; 
}
.screen .current{
  color: black;
  font-size:12vw; 
}