body{
    font-family: 'Fira Sans', sans-serif; 
    background-color: #D7433F;
}
.container {
    height: 500px;
    width: 300px;
    margin: auto;
    display: flex;
    flex-flow: column;
    box-shadow: 0 0 10px 0 rgb(0, 0, 0); 
}

.display {
    flex: 1;
    background: #2E3548;
    display: flex;
    flex-flow: column;
}
.btns{
    flex: 2;
    display: flex;
    flex-wrap: wrap;
}
button {
    flex:1;
    padding: 26px;
    text-align: center;
    text-decoration: none;
    font-size: 16px;
    -webkit-transition-duration: 0.4s; /* Safari */
    transition-duration: 0.4s;
    cursor: pointer;
    background-color: #F4F5F9;
    color: black;
    border: 1px solid #FFF;
    background-image: none;
    font-family: 'Fira Sans', sans-serif; 
    outline: 0;
    -webkit-box-shadow: none;
            box-shadow: none;
         

}

button:hover {
    background-color: #e7e7e7;
}

button:nth-child(4n+0) {
    background-color: #DCDFE6;
    border: 0px;
}
button:last-child{
    background-color: #D7433F;
    color: #FFF;
}

button:nth-last-child(2){
    padding: 24px;
}

span{
    flex: 1;
}
p{
    color: #FFF;
    text-align: right;
    margin: 0px;
}

.display-s {
    padding: 14px 10px 0px 0px;
    font-size: 28px;
}

.display-r {
    font-size: 55px;
    padding: 0px 10px 0px 0px;
}


 /* for mobile compatiable */
@media (max-width: 600px) {
    .container {
        margin: 0px;
        height: 100%;
        width: 100%;
         box-shadow: none; 
    }
    button {
        padding : 46px;
    }

    button:nth-last-child(2){
    padding: 39px;
    }

    body{
        margin: 0px;
        background-color: #FFF;
    }
} 

/* style for toggle button */
.switch {
  position: relative;
  display: inline-block;
  width:  40px;
  height: 20px;
  margin: 5px 0px 0px 5px;
}

.switch input {display:none;}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #D7433F;
  -webkit-transition: .4s;
  transition: .4s;
}

.slider:before {
  position: absolute;
  content: "";
  height: 15px;
  width: 15px;
  left: 4px;
  bottom: 3px;
  background-color: white;
  -webkit-transition: .4s;
  transition: .4s;
}

input:checked + .slider {
  background-color: #1ebd40;
}

input:focus + .slider {
  box-shadow: 0 0 1px #2196F3;
}

input:checked + .slider:before {
  -webkit-transform: translateX(20px);
  -ms-transform: translateX(20px);
  transform: translateX(18px);
}

/* Rounded sliders */
.slider.round {
  border-radius: 34px;
}

.slider.round:before {
  border-radius: 50%;
}